United States Patent 3796132

A digital hydraulic system converts binary digital input information into displacement of a digital drive. An air reader is used to operate binary latch valves through an air hydraulic interface. A flow sensing system and a hydraulic logic unit cooperate to provide high speed exchange between the piston adders of the digital drive prior to displacement of the load. A hydraulic cylinder sweeps the load about a vertical axis. A self-cooling, air-driven hydraulic pump with an accumulator, provides relatively constant pressure. A damper secured to the piston adders has an additional drive for providing precise location at the end of damping. An incremental paper tape feed with a four motion rack with toggle action indexes the air reader.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
International Classes:
F15B11/12; G05B19/43; G05B19/44; (IPC1-7): F15B11/18
Field of Search:
92/8,9,10,11 91
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US Patent References:
3176801Precision motion control device1965-04-06Huff
2891514Positive stop cylinder1959-06-23Moeller

Primary Examiner:
Geoghegan, Edgar W.
Assistant Examiner:
Ostrager, Allen M.
Attorney, Agent or Firm:
Jones II, Graham S.
Parent Case Data:

This is a division, of application Ser. No. 824,424 filed May 14, 1969 now U.S. Pat. 3,726,190.
What is claimed is

1. In a mechanism having a relatively fixed member, a movable member and damping means coupled between said movable member and said fixed member for exerting a damping force upon said movable member, the improvement comprising selectively releasable means for positively positioning said movable member relative to said fixed member, during engagement of said releasable means,

2. Apparatus including,

3. In a mechanism having a relatively fixed member, a movable member and damping means cooperating with said movable member for exerting a damping force thereon, the improvement comprising selectively releasable means for positively positioning said movable member relative to said fixed member during engagement of said releasable means with said movable member,

4. In a damping mechanism having a relatively fixed member, a movable member and damping means coupled to said movable member for exerting a damping force thereon, the improvement comprising said damping mechanism including a selectively actuated locating means including a piston in a piston chamber for positively urging said movable member towards a preselected position relative to said fixed member during actuation of said piston, said piston being mechanically coupled with said movable member by rigid means during urging by said piston of said movable member towards said preselected position, and control means for controlling the sequence operations of said damping mechanism operating said locating means subsequent to damping by said damping means said damping mechanism having its movable member secured to a load, said control means permitting said damping mechanism to provide damping while initially passing beyond said preselected position freely and then said control means subsequently providing accurate positioning by actuating said piston for driving said load to said preselected position, said movable member being secured to an incremental drive and during an initial interval of time said control means actuating said incremental drive to cock said damping means in the reverse direction of its ultimate direction of travel when damping said movable member.

5. Apparatus in accordance with claim 4 including means for arresting said incremental drive, said means for arresting restraining the distal end of said incremental drive from said damping means during said initial interval of time of operation of said drive for cocking of said damping means in the reverse direction from its ultimate direction of travel to occur later.

6. Apparatus in accordance with claim 4 wherein said incremental drive comprises a plurality of pistons in cylinders connected in a series, and said means for arresting comprises means for clamping the distal end of said series to be stationary relative to said fixed member during cocking of said damping means.

7. Apparatus in accordance with claim 4 wherein a control system is coupled to said damping means and said incremental drive for automatically cocking said damping means prior to each motion of said incremental drive and subsequently automatically engaging said selectively releasable means for positively positioning said movable member.


This application is related to copending U.S. application Ser. No. 694,941 by H.A. Panissidi entitled "Manipulator", U.S. Pat. No. 3,550,630 issued on application Ser. No. 695,139 by H.A. Panissidi entitled "Serial-to-Parallel Hydraulic Device", and U.S. Pat. application Ser. No. 824,425 now U.S. Pat. No. 3,641,877 entitled "Flow Sensing System and Valve" by R. C. Hebert, filed herewith.


1. Field of the Invention

This invention relates to damping devices. More particularly, this invention relates to damping devices which are secured to a digital drive mechanism.

2. Description of the Prior Art

Conventional damping mechanism may contain springs or other means for returning the damper to a zero or neutral position. However, previously known damping mechanisms in the art have not included any means for precisely locating the moveable mechanism relative to a fixed member. Accordingly, in connection with accurate digital drives, it is highly desirable to provide some means for providing damping and at the same time including control mechanism and means for precisely locating the load at the end of the displacement cycle.

Prior air driven engines have toggled relatively slowly thereby causing a fairly high degree of regulation or fluctuation in output pressure from the oil pump. Faster systems have often employed electrical motors which have created a significant heat dissipation problem. External cooling arrangements have been supplied for such systems including radiators, circulation of oil to the radiators on the exterior of the system. Such radiators require space and are costly.

LOCATION. In connection with digital drives, means are provided of accurately locating the first member of the digital drive relative to a zero position after each operation of the digital drive to displace the load in a predetermined direction has been accomplished. In another aspect, means are provided for initially cocking the damping mechanism into a position in the opposite direction from the final direction of displacement. Subsequently, upon deceleration by the damper with minimum overshoot, the load is caused to locate by positive locating means in the damper.

An object of this invention is to provide accurate location of a digital drive subsequent to the major displacement motion of that drive and damping thereof.

A further object of this invention is to provide means for efficient damping of a drive subsequent to displacement of the load.

A related object is to provide damping with minimum overshoot.

An object to this invention is to provide means for reversing the direction of operation of an air engine prior to the time that the pump being driven thereby reaches its extreme position.

The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.


FIG. 1 shows a schematic block diagram of the overall system employed in accordance with this invention.

FIG. 2 shows the relationship between the various sections of the large diagram of FIGS. 2A-2K. FIGS. 2A-2K show the overall connections between the various subsystems of the integrated adder drive assembly employed in accordance with this invention, and in FIGS. 2K and 2L additional details of the system are shown.

FIG. 3 shows the relationship between FIGS. 3A and 3B.

FIG. 3A and 3B show the displacement characteristics of valves and mechanism in the hydraulic system shown in FIGS. 1 and 2A-2K in accordance with this invention as a function of time.

FIG. 4 shows the sweep and arm clamping mechanisms for the base of a manipulator's arm.


Control system

referring to FIG. 1, the present system includes an air reader 10 for reading a perforated tape 11 which provides output pulses to a hydraulic control system by means of an air line 12 and an air hydraulic interface 13 which converts pneumatic pulses to hydraulic values. The air hydraulic interface transfers pulse inputs to hydraulic binary latch valves 14 which "remember" or retain a "0" or a "1" condition, depending upon the sense or polarity of the input transmitted from reader 10 through the interface 13.

The outputs of the latch valves are in general connected via lines 141, 142 to extend or retract a corresponding one of several piston adders 15 which comprise a series of interconnected pistons and cylinders employed to provide binary displacement of a load bearing shaft 156 by unit distances, in binary progression from from one thirty-second inch to almost 32 inches in binary steps up to 16 inches.

For the 1, 2, 4, 8 and 16 inch long piston adders, a set of variable orifices in a velocity control valve 17 are provided between lines 141, 142 and 342 for the purpose of controlling the rate of displacement of the pistons with larger displacements.

In order that the piston adders 15 and the output shaft 156 connected to one end thereof may be accurately located rapidly, a damper 18 is provided which permits the piston adders 15 to be cocked during an "exchange" interval.

The exchange interval is a time during which the output shaft 156 is firmly retained in position by braking or arresting means shown in part herein and shown in full in above U.S. Pat. No. 3,575,301 and the piston adders 15 are reset and extended to the extent that certain pistons are retracted and certain other pistons are extended. During the "exchange" period the velocity control valve 17 will be held wide open to permit exchange at maximum permissable velocity, since the piston adders 15 will not be under load.

Referring again to the damper 18, when the load has been fully positioned where desired, the damper 18 provides hydraulic damping with minimum overshoot and is actuated via line 75 by hydraulic logic unit 20 to provide mechanical positioning ultimately to a precise home position. Cocking minimizes overshoot and optimizes use of time for the steps of exchanging piston locations and driving the load.

In order to provide regulated hydraulic pressure to the system a hydraulic power supply 22 is provided. It supplies pressure for latching and to the central lands 16 of spool valves in the hydraulic logic unit via line 116 and the flow sensing system 23, via line 47, which controls two "bleed" lines 24 and 25 to the hydraulic logic unit 20 as a function of the velocity of flow through line 47, the flow sensing system 23 and line 52 to the latch valves 14 which connect to the piston adders 15. When the flow or displacement of piston adders declines below a minimum value the bleed lines 24 and 25 are blocked by flow sensing system 23. A bypass control line 38 from the hydraulic logic unit 20 controls a port 40, 41 inside the flow sensing system 23 to control one of the flow sensing units therein.

The hydraulic logic unit 20 can be started and stopped. Since the logic unit 20 controls the toggle line 76 which powers the feed advance of the tape reader 10, when switch 54 is operated, air is blocked from operating the logic unit 20 and at the end of a displacement cycle operation of the system stops.

As the drive is adapted to displace a plurality of members, a decoder 30 is connected to the logic unit 20 via line 94, and to certain ones of the latch valves 14, to operate aligners 31 to hold the various members to be displaced by the output shaft, through a linkage, not shown, which is similar to that shown in copending U.S. Pat. No. 3,575,301. Clamp rack 33 is engaged when it is desired to drive the Z arm of the output, for example, a manipulator, as shown in FIG. 4.

A set of sweep sense units 33 and a sweep cylinder 34 are employed to sweep a load on support 190 about an axis upon an input via line 198 or 200 from one of the latch valves 14. The sweep sense unit 33 is connected to bleed line 25.

Referring to FIGS. 2A-2J, the overall system is shown in greater detail than in FIG. 1 and the connections between the various systems are shown.


The exchange and move flow sensing system 23 includes a cylindrical exchange sense piston 35, a cylindrical move sense piston 36 and a bypass poppet 37. The bypass poppet 37 is controlled by pressure in a line 38 connected to the lower output of flow spool valve 39 in FIG. 2B. When the bypass poppet 37 is to the left, its valve 40 will seat on surface 41 to close off the inlet 42 to the exchange sense piston 35. It should be noted that the exchange sense piston 35 and the move sense piston 36 are each spring biased by springs 43, coaxial therewith in the larger coaxial bore 44 in the pistons 35 and 36. The pistons 35 and 36 are grooved at 45 to connect the bleed lines 24 and 25 to the return 46 to the low pressure side of the hydraulic pressure supply 22. Pressure from the hydraulic pressure supply 22 is supplied by line 47 to the inlet 48 on the upstream end of the valve 40 of the bypass poppet 37 which may or may not be open, as described above, and to the inlet 49 to the move sense piston 36. Each of the exchange sense piston 35 and the move sense piston 36 is provided with a smaller axial bore 50 to the upstream end thereof confronting the corresponding inlet 42 or 49 thereof. The orifices 50 are selected so that when the pressure differential across the orifice 50 is above a predetermined level, then the pistons will be driven upwardly against the pressure of the springs 43 to align the grooves 45 with the bleed lines 24 and 25, thereby connecting the bleed lines to return 46. The by-pass poppet 37 provides a means for selectively actuating the exchange sense piston 35. In this way, the flow sensing system may be operated in two modes depending on whether the piston adders 15 are being driven in the move or exchange mode of operation. A further feature of this system is that since each of the orifices 50 is substantially of the same order of magnitude in diameter and length, the resistance to fluid flow provided by each thereof is substantially of the same order of magnitude. When both are connected in parallel, the resistance to flow is nearly halved, or conversely, flow doubles, approximately. As will be noted, the outlets 51 of the two sense pistons are connected to line 52. Since the two sense pistons are in parallel, and therefore the orifices 50 are in parallel, if the bypass valve 46 is open, the quantity of flow through each of the two orifices 50 will be substantially equal and accordingly the rate of flow into the line 52, if sufficiently large and unrestricted will in general be approximately doubled. Accordingly, when the exchange sense piston 35 is permitted to operate by the bypass poppet 37, the quantity of fluid flowing from lines 51 through line 52 to the piston adder drive will be greater and the velocity of displacement in the exchange period will accordingly be far greater. (See U.S. Pat. No. 3,641,877 for a more complete description under this section).


The hydraulic logic unit comprises a plurality of spool valves, delay pistons in cylinders which comprise compliance or capacitive units which require a time delay for displacement from one end to the other end of the cylinder in which they are housed; orifices, check units described below in connection with FIG. 2L, interconnections and outlets which control other elements of the overall system. Certain of the spool valves are spring biased into one position as indicated by helical springs in longitudinal cross section. Certain other of the spool valves are latch valves which are held in position by hydraulic latching means. Such a latching means comprises a passageway 600 tangential to one end of a land of a spool located so that it supplies fluid under pressure to the side of the land regardless of spool position, and contacts a small area on one side. The land thereby creates a laminar pressure gradient along that side which is coupled to the return lines through leakage. There is a ratio of pressures across the land of several times the pressure on the inlet side to the pressure on the low pressure side which pushes the land to one side and inhibits longitudinal sliding because of friction forces. Pressure can be relievd during movement of the spools to relieve friction forces.

When the start diaphragm 56 is operated by the pressure at inlet 53 (assuming pneumatic toggle 54 is on) from the reader start apertures 28 in the tape via line 29, or otherwise provides input from a two way solenoid or valve 27, etc. then the start spool valve 55 is driven upwardly thereby connecting its lines 57 to the right and to the left to higher pressure from the central annular groove 16 as the central land or ring passes therabove. Accordingly, pressure will be applied at the junction 58 between the orifice checks (described below in connection with FIG. 2L, 59 and 60 which connect to the probe spool valve 61, the probe delay piston 62, and the probe phase piston 63. On the left side, the line 57 is connected to the point 64 which supplies the lower end of flow spool valve 39; and by orifice check 65 point 64 is connected to line 66 and phase piston 67. It will be noted that line 66 is connected to bleed line 25 and both are connected to the upper end of the flow spool 39, valve which is spring biased downwardly. Accordingly, when the flow phase piston 67 has moved fully to the top of its cylinder at the end of 60 milliseconds, then as soon as the exchange sense valve causes the bleed line 25 to be disconnected from the return 46, the pressure on the line 25, and therefore on the upper end of the flow spool valve will be increased and the flow spool valve will be driven back to its position as shown in FIG. 2B by the force of the spring 87. Initially, then, as soon as the start valve is operated, the flow valve will be operated also and pressure will be placed upon line 38 from the central high pressure source and line 38 will connect pressure to the bypass poppet, which will remain open until the flow valve is driven back to its home position. Since line 38 is connected to the lower end of delay piston 68 and to the lower end of move spool valve 69 which is biased upwardly, the move valve will be driven rather rapidly upwardly shortly after the flow valve is driven upwardly, by the spring 53. It should be noted that later, when flow is reversed, the delay piston 68 cooperates with the orifice check 70 to provide a long time delay before it is possible for the move valve 69 to be reset down against the force of its spring 53. When the move valve is driven upwardly, the line 71 from the upper end thereof has the pressure thereon released, thereby releasing pressure on the upper end of the exchange spool valve 72 which will have pressure on the lower end thereof from the line 38 which, after the delay valves have permitted the pressure to build, will then shift upwardly. The damp spool valve 73 has a spring bias at the lower end thereof, and will shift shortly after the exchange valves shifts, thus releasing the pressure from the uper end thereof. Line 75 is connected to the damper 18 including its pistons as shown in FIG. 1 and FIG. 2J secured to one end of the piston adders 15. At this point in each displacement cycle of the drive, pressure is released from the damper positioning pistons 80. Accordingly, the damper is released so that it can be cocked during the exchange mode of operation. After an interval of about 20 milliseconds selected to allow pilot valves 85 to be positioned, according to the data in the tape, the probe delay piston 62 will have reached the opposite end of its cylinder. Accordingly, the pressure at the lower end of the probe spool valve 61 will have reached a high enough level to overcome the spring biasing force at its upper end and to drive the valve upwardly thereby providing pressure on probe line 81 from the central annular pressure source 82 as the central land passes thereacross and the lower land passes across the return 83. The probe line 81 is connected to each of the inlets 84 of the pilot valves 85 to provide pressure to their central annular cavities. The probe pressure is employed to adjust the hydraulic binary latch valves 14 in accordance with the binary valves provided by the air reader 10. Thus, the binary drive will be reset in accordance with the most recent input data provided thereto in the tape under the air reader 10. It will be understood that another variety of input source could be connected through a suitable interface. About 40 milliseconds after start, the probe phase piston 63 will rise to the top of its somewhat longer cylinder and at that time will cause a pressure build up at its lower end, which is connected to the upper end of the probe spool valve 61 which is spring biased downwardly. Since the presures of the opposite ends of the probe spool valve 61 will be equal and opposite, accordingly, the probe spool valve will be driven downwardly by its spring 86. At this time pressure will be removed from the probe line 81. This will not mean the end of the exchange motion of the piston adders which will be under control of the hydraulic latch valves 14 which will remain as positioned during the probe portion of the control cycle of the hydraulic logic circuit 20. So long as the exchange continues, the exchange sense piston 35 will remain in its upper position against its spring as will the move sense piston. At a predetermined point, when the exchange velocity ends and the flow of hydraulic fluid due to elimination of pressure differential and the end of flow through the sense pistons 35 and 36, they will both move down to their spring biased lower positions. Accordingly, bleed line 24 will be closed momentarily and bleed line 25 will be closed for the remainder of each cycle of operation of the hydraulic logic unit 20. Line 25 will thereby cause build up of pressure on the upper end of the flow valve 39 as mentioned above and the spring 87 at the top thereof will act to drive the flow valve 39 down. Pressure will build on the line 24 and line 89 from lines 16 and 688 through the flow valve 39. However, the delay piston 68 and the orifice in orifice check 70 will defer the build up of the pressure in the lines 24 and the build up of the inlet 89 to move valve 69, and actually the move valve 69 will not be operated at this time, because, a short time later, bleed line 24 will be reconnected by move sense piston 36 to the return 46 and will bleed pressure from inlet 89. Line 688 will apply pressure immediately to the central cylindrical cavity 188 of the exchange spool valve 72 held up by pressure in line 38 and thereby providing pressure on line 90 to the lower end of the aligner latch valve 74. The aligner latch valve 74 will be driven upwardly since the upper end thereof will have low pressure, as on line 75. The pressure had been released as described above. Accordingly, the aligner latch valve will release pressure on line 91 to permit the aligner spool valve 92 to be driven upwardly by a spring 93. This will apply pressure to line 189 resetting start spool valve 55 applying pressure from line 116 to reset line 88 to reset all of the pilot valves 85 and will release pressure from line 94 which is connected to the aligners 31 so that one of the members connected to the output of the load shaft can be driven at this point. Further, line 94 is also connected to the velocity control valve 17 in order to reduce the orifice into the piston adders during the period of driving of the load. As the load is now free to move, the piston adders can move and accordingly flow will resume in line 52 (as indicated above in connection with line 24) and for that reason the pressure drop across the move sense piston will resume and the move sense piston will be driven upwardly again thereby bleeding pressure from the bleed line 24. However, the bypass poppet 37 will have pressure released therefrom on line 38 since the flow valve 39 will, as described above, have been driven downwardly thereby connecting line 38 to the return 95. Pressure on line 76 from aligner latch valve 74 in FIG. 2A to the reader 10, FIG. 2D, will operate the reader feed mechanism. In addition, in the purge control in FIG. 2B, pressure in line 76, will operate a pair of pistons 96 from line 97 attached to the line 76 to drive the spool valves 98 and 99 to the left so that the pressure on line 100 will be connected down into the lines 101 which are connected to the purge inlets to the diaphragms 102 in the air hydraulic interface 13. Air under 10 psig pressure will be driven through the purge inlets 101 across the surface of the diaphragms of the interfaces 102 and out through the reader lines 12 to purge or to drive oil out of the system and to clear and chad and other material from the lines 12, and 112. The remainder of the purge cycle is described below, after discussion of concurrent valve operations.

The pressure will remain on line 76 until such time as the motion of the piston adders ends and the move valve 69 is driven downwardly in final closure of the bleed line 24 by closure of the move sense piston 36, so that at that time, line 71 will drive the exchange valve 72 down removing pressure from line 90 and at the same time applying pressure to line 103 through the orifice of orifice check 104 and delay piston 105 after a time delay of 90 milliseconds, drive the damp valve 73 down against its spring and to apply pressure on line 75 therefrom to drive the aligner latch valve 74 down and remove pressure from line 76 and apply pressure to line 91 and through the orifice in the orifice check 106 and delay piston 107 cause a time delay to run to drive the aligner valve 92 down against its spring 93. The aligner delay piston 107 will require another 120 milliseconds to drive downwardly. Accordingly, final alignment will not occur for some time.

However, referring again to the purge unit, in FIG. 2B, when line 71 is pressurized, the piston 99 will be driven to the right and atmospheric pressure from line 199, to atmosphere, will be permitted to resume inside the purge and reader lines 101 and 12 so that the diaphragms 102 may be returned to atmospheric pressure. Then when pressure is removed from line 76 as a result of return of the aligner latch value to its lower position, the spring 108 of the spool valve 98 will act to drive that spool valve to the right and to shut off connections 101 to the diaphragms. It should be noted that the 10 psig air supply 109 is connected to line 110 which applies positive pressure to the air pressure head 111 for passage through the tape 11 into the inlets 12 to the diaphragms 102.

During the time that the purge spool valve 98 is to the left, the blocking of pressure by valve 98 from line 110 to the air reader 111 will prevent blowing air down into the diaphragms during the purge cycle when air is to be blown in the reverse direction.

Air reader

the perforated tape reader shown in FIG. 2D will operate in ordinary machine shop air typical of industrial locations, which is contaminated with dirt, oil and water. Therefore, cyclic purging of lines 12 is necessary because the reader sense hoses are extremely thin, usually 0.030 inches I.D. making them vulnerable to clogging.

In order to avoid costly memory devices and serial to parallel converters for some applications, the reader is designed to advance the tape up to two characters per step, allowing the system to accept two characters of data simultaneously. The hydraulically driven reader, as shown schematically, consists of an air reader head with 16 ports to accept two perforated characters of an 8 channel Mylar tape. The 16 ports of the air reader head are connected by sense hoses to the 16 diaphragm driven hydraulic pilot valves. The air reader head, supporting the tape, is pressurized with 10 psig air by a spring loaded air manifold. A hole in the tape will allow its corresponding diaphragm actuated pilot valve to be pressurized with 10 psig from the air manifold.

The air reader 10 includes an air pressure head 111 which is spring biased downwardly by a spring 117. The tape which is used includes 8 longitudinal columns and is read in groups of two rows of characters such, as shown in FIG. 2D, simultaneously. Accordingly, the feed must advance two rows of holes for each reading cycle. The top hole in the first row is the start control. The next two holes are M2 and M1 controls for FIG. 2E and the next holes ones are the fractions from one-half inch down to one thirty-second inch. In the second column in the second hole, the sweep mode of operation of the manipulator which would be attached to the device is entered and in the third hole, the bit for the grip mode of operation of a manipulator gripper would be entered. In the last five holes in the second column, the bits for the 16, 8, 4, 2, and 1 inch piston adders would be entered. The head 111 is designed so as to provide air pressure above all 16 holes and underneath the holes would be aligned the various inlets 12 to the diaphragms 102 shown in FIGS. 2E-2H. The feeding mechanism is comprised of a sprocket wheel 118 which operates in cooperation with perforations 119 in the tape 11. The sprocket wheel 118 is secured to shaft 120 and the shaft 120 is journalled for rotation in response to torque applied by gear 121 which is retained in position by detent pawl 122 which is spring biased downwardly by spring 123. The pawl 122 carries a pin 124 at one end thereof which fits into the teeth of gear 121. The gear 121 is adapted to mesh with a rack 125 which can be raised into gear by a toggle lever 126 which is pivotally secured by pin 127 in which toggle lever carries rack 125 on pin 128. The rack 125 is reciprocably longitudinally slideable on drive wire 129 secured at its distal end to a piston 130 slideably carried in cylinder 131 for longitudinal reciprocation therein. The cylinder 131 contains a spring 132 at the distal end of the piston 130 for biasing the piston 130 leftwardly. At the opposite end of the cylinder is a release aperture 333 to permit motion to the right. The opposite end of the toggle lever 126 is secured to a drive wire 133 by means of pin 134 to bifurcated end 135 of drive wire 133. Drive wire 133 is secured at its distal end to a spool valve 136 carried in cylinder 137. The spool valve 136 is spring biased leftwardly by spring 138. At the leftward end of piston 130 is an inlet 139 connected from the central portion of cylinder 137 adapted for communication with the two inlets 81 and 281 into the lower cylinder 137 from the central portion thereof. At the leftward extreme end of cylinder 137 is located an inlet from line 76 from the aligner latch valve lower outlet, which is provided for operating the reader. If pressure were applied to line 76, it would function to pull the toggle lever 126 counterclockwise about pin 127 by means of flexing of drive wire 133. Lever 126 and pin 128 will drive the rack 125 up into engagement with the gear 121 preparatory to actual driving motion. When this occurs, i.e., valve 77 is to the right, the connection of line 139 to the cylinder 137 will be made to the line 116. This will drive the piston 130 to the right against the reaction of its spring 132 pulling wire 129 and the rack 125 to the right and turning the gear 121 counterclockwise about shaft 120 thereby advancing the tape 11 two character positions to the left as the sprocket 118 is turned on the shaft 120 counterclockwise. It should be noted that while the probe pressure is employed for the purpose of driving the air reader, that such probing does not occur until after the pressure on the purge line 76 has been generated by means of driving the aligner latch valve 74 to its upper position after the exchange is terminated. The adjustment of the pilot valves during the probe cycle will have been completed well prior to that time; and with the application of pressure on line 76, and the displacement of the purge spool valve 98 to the left, the pressure applied on line 110 to the air pressure head 111 will have been blocked by the leftward land of the spool valve 98.

During the period the rack rotates the drive gear, there is a substantial separating force between the rack and gear due to the pressure angle of the gear teeth (20°) which is supported by the toggle shaft.

With pressure removed from the left end of the toggle valve, its spring will drive it to the left rotating the toggle lever 126 to its initial position. The toggle valve will expose port 139 to its port 281, thereby removing pressure from the left-hand side of the drive piston allowing it and its rack to return to its initial position by the reaction of its spring.

It is during this tape advance cycle described above that the pilot valves 85 of the hydraulic system must be physically locked by pressure in line 88 from responding to the tape holes as they move under the air reader head 111, and at the same time, the sense hoses 12, diaphragms 102 and air reader ports must be flushed out with a reverse air blast to purge the air sense system of any contamination from the previous read cycle. Line 76 to the purge control 99 and isolating valves 98, respectively, causes both valves to move to the left, valve 98 moving against the reaction of its spring 108. The transfer of the multiple land isolating valve 98 will expose all of the purge hoses 101 to the port 100 of the transferred purge control valve 99 and, at the same time, shut off the air pressure to the air manifold 110 by the scissoring action of the extreme left-hand land of the isolating valve 98.

The port 100 of the purge control valve exposed to its 10 psig port 109 provides a reverse air flow through the 16 diaphragm chambers, sense hoses and the air reader head ports with the foreign matter, if any, being expelled between the air reader head and tape to the atmosphere. Following this purge cycle, the entire reading circuit and diaphragms must be depressurized before releasing the locked diaphragm actuated pilot valves. In order to accomplish the depressurization, the purge control valve must be returned to its initial position before the return of the isolating valve 98 sealing off all the purge hoses 101.

A time delay network consisting of an orifice in series with move delay piston 68 controls return of the purge control valve 99 to its initial position for exposing all the purge hoses to the atmosphere through port 281. Again at the end of the tape advance cycle the aligner latch valve 74 will be restored to its initial position with the removal of the hydraulic signal, exposing line 76 to the reservoir allowing the tape advance circuit and isolating valve to reset to their initial position.

The reset of the isolating valve will permit air pressure to the air manifold and, at the same time, seal the individual purge hoses to prevent cross talk. With the release of the locking pressure from the pilot valves, it will allow the diaphragms to respond to a hole in the tape causing the transfer of the pilot valve against the reaction of its spring.

An advantage of the above described pneumatic tape reader is that it has a minimal number of moving parts, is capable of reading two characters simultaneously, and in contrast with the type of reader which had been required in connection with this type of system before, eliminates the need for a character buffer storage unit.

Use of pressure instead of vacuum sensing of the tape holes minimizes the problem of contamination and costly filtration.

Air hydraulic interface

from the lines 12 of the air reader 10, connection is made, as described above, to the lines 12 to the diaphragms 102 in FIGS. 2E-2H. When pressure is applied above a hole, then one of the diaphragms 102 will operate to cause its associated pilot valve 85 to be driven leftward. This will cause the associated latch valve 14 to be driven leftward also, during the application of pressure to the probe line 81, as the line 84 will be connected to the right-hand side of the central land of the pilot valve 85. Accordingly, the right-hand end of the latch valve 14 will have pressure applied thereto. Referring to latch valve 14-16 on the left-hand side of FIG. 2F, the numeral 14-16 indicates that the latch valve is connected to the 16 inch piston adder 140 by means of lines 141 and 142. The right hand one of the lines 142 is the one which will have the pressure applied to it in a case in which the pilot valve has been actuated by the reader. It will be seen that the line 142 passes through the velocity control valve 17 in FIG. 21, and if pressure is applied on line 94, then the spool valve 143 will be driven to the right and the orifice through the velocity control valve 17 will be reduced for the longer ones of the piston adders from lengths of 16 inches down to 1 inch. As pressure is applied through line 142, the fluid will flow through line 342 into the space in cylinder 145 to the right of piston 144. If the load is released from alignment or if other pistons are also being displaced at the same time, as in the case of exchange between pistons, then there will be freedom for the cylinder 145 to move relative to the piston 144, and, of course, since the pressure is applied to the right-hand side of the piston and cylinder, the cylinder will move to the right. In the opposite case, the piston 144 would move to the left, if the load were released. In FIGS. 3A and 3B, a graph is shown of the displacement characteristic for the two inch piston adder 146 and the 1 inch piston adder 147. In FIG. 2J, the 1 inch piston adder 147 is shown with its piston 148 extended in cylinder 149, whereas the two inch piston adder 146 is shown with the piston 150 in its collapsed position in cylinder 151. If, for example, it were desired to extend the 2 inch piston adder 146 and to collapse the one inch piston adder 147 during the exchange period, then the orifice provided by the spool valve 143 in the velocity control valve 17 would be retained open and at that time the pressures applied would be on the left-hand end of piston adder 146 and on the left-hand end of the piston adder 147. If at the same time the damper 18 were released, in the sense that the positioning pistons 80 had pressure removed therefrom, then the shaft 152 could move to the right until the damper piston 153 came to rest at the right-hand end of its cylinder 154. Thus, during the exchange mode of operation, in this case, since the damper has a maximum displacement of about one-half inch and since the difference between the 2 inch and 1 inch piston adders is 1 inch, the entire assembly from the piston adder cylinder 149, to the right, will be moved about one-half inch to the right. At the same time, the piston 150, which is connected by rod 155 to the piston 148, will move about 11/2 inches to the right. The cylinder 151 will remain in place. In this manner, very rapid displacement between one or more of the piston adders may occur without any motion of the load and with only slight motion of the damper, if desired. This process is referred to herein as exchange. Exchange can occur at high velocity for two reasons: First, the load is disconnected from the piston adders and accordingly there are no problems associated with braking the heavy load when operating in the rapid exchange mode of operation of the adder drive. Secondly, the orifice or the rate of flow of fluid to the adder drive can be regulated. Such regulation is afforded in two ways. The first way in which regulation of flow is accomplished is by means of the bypass poppet 37 in conjunction with its hydraulic control circuit described above. The second way in which flow is controlled is by means of a velocity control valve 17. The velocity control valve 17 is controlled through line 94 by means of the hydraulic logic 20. Heretofore, when the load had been given an instruction to move from one position to another, a rather lengthy period of time expired during which the piston adders exchanged with each other at the maximum velocity permissible with a full load secured to the end of the output shaft 156 of the adder drive. This was most objectionable and required far longer for the total system to operate. However, after considerable experimentation it was discovered in connection with this invention that the use of the exchange concept of higher velocity displacement of the adder drive when in the idling mode of operation would permit far more rapid overall operation of the system in connection with a serial digital drive.


prior piston adder arrangements have incorporated a damper for each and every one of the piston adder units; which in this case shown in FIGS. 2I and 2J and includes 10 piston adders. Thus, in the past, the instant unit would include 10 dampers.

In accordance with this invention only one damper is required. In FIG. 2J, rod 152 is secured by a bar or plate 157 to a shaft 158 secured to a single damper piston 153. Damper piston 153 is adapted to reciprocate in bore 154 in the housing block of the damper 18. As in conventional damping mechanisms, apertures 163 are provided at opposite ends of bore 154 so that motion of piston 153 and shaft 158 either to the right or the left will be damped by the restricted flow of oil through the appropriate orifice 163. Orifices 163 are connected in a bypass hydraulic circuit and to pressure line 115 which is connected to line 47 at the outlet of the hydraulic pump. Hydraulic line 115 is not shown in the drawing except at its inlets and outlets. Alternatively line 115 in FIG. 2J could be a separate pump if desired. The sole purpose of connecting line 115 is to maintain hydraulic pressure on both sides of orifices 163 and in bore 154, to provide oil in the lines to orifices 163 and cylinder 154 continuously so that damping can occur. Line 115 can be omitted if the system bore 154 is filled with fluid and orifices 163 are connected by a closed line filled with fluid which will maintain such pressure. Shaft 158 is secured at its opposite end to a bar or plate 159. The plates 157 and 159 cooperate with the rods 160 extending from a pair of positioning pistons 80 carried inside cylinder 161 in the housing of the damper 18. The bars or plates 157 and 159 are held in alignment by guide rod 600 extending through plate 159. The pistons 80 are employed for final positioning of the damper piston 153 after it has performed its function of smoothly damping the load, with minimal overshoot, as it is nearing the end of its excursion. Pressure on line 75 is to be removed at the beginning of operation of the damper. Thus, the rods 160 will be retracted or since pressure has been removed from positioning pistons 80 to release rods 160 they will permit the damper to be driven in any desired direction.

In connection with this invention, it has been found desirable to cock the damper during exchange. Cocking of the damper at this time tends to speed the operation of the system. During the initial moments of each cycle of operation of the piston adder drive, it has been found desirable to drive the damper piston 153 in the opposite direction from that in which it will ultimately be traveling at the end of that cycle so that at the end of displacement of the entire sytem, the damper piston 153 will be moving towards its central location (in which it will be finally positioned by the rods 160). At the end of displacement of the load by means of the digital piston adder drive, the kinetic energy of the moving load will urge the damper piston 153 towards its position in the center of bore 154 and the force will cause circulation of fluid through the orifices 163 in order to decelerate the load to a smooth stop, thereby minimizing overshooting of the target. Then if the rods 160 are operated again by pressure on line 75 transmitted to pistons 80, highly accurate positioning of the outputs shaft of the piston adder 15 will result, relative to a fixed reference point. As an alternative form of damper, shaft 152 of the piston adders may be connected as in FIG. 2K to a different damping piston 553 carried in cylindrical bore 554 in damper housing 518. The line 75 from the hydraulic logic 20 is connected to operate spring biased locating piston 580 having a conical tip 581 for cooperation with the overlapping conical surfaces 582 at the center of piston 553. Opposite ends of bore 554 are connected through passageway 662 and orifice 663 which control the resistance to flow of fluid through the hydraulic damping circuit.

The exchange interval is a time during which the output shaft 156 is firmly retained in position by braking or arresting means shown in part herein and shown in full in about U.S. Pat. no. 3,373,301 and the piston adders 15 are reset and extended to the extent that certain pistons are retracted and certain other pistons are extended. During the "exchange" period the velocity control valve 17 will be held wide open to permit exchange at maximum permissible velocity since the piston adders 15 will not be under load. The ultimate force of the piston adders will urge the piston 153 to one end of the cylinder 154 until the braking or arresting means is removed, cocking the piston 153. At the end of displacement of the load by the piston adders, the piston 153 will be driven in its ultimate, damping, direction of travel by the load on shaft 156.

Upon completion of a step of displacement and after damping has been effected, then pressure is applied on line 75 and locating piston 580 drives the piston adders 15 and the load on shaft 15 into final position by homing into the position shown in FIG. 2K.

FIG. 2L shows a symbol for a hydraulic component referred to herein as an orifice check shown as a pair of slanted lines 700 forming an acute angle 701 pointing in the direction of low velocity flow in which the bypass check valve 702 is seated but the low velocity flow from 704 to 705 continues through an orifice 703 which permits flow at a low velocity.

Decoder with tree

latch valve 14-M1 is connected through lines 141 and 142 thereof to opposite ends of a spool valve 170 which may be driven downwardly in the event that a hole appears in position M1 in the tape when the reader reads the tape. This will cause fluid to flow from aligner line 94 into the upper end outlets 173 of the spool 171. Line 173 will be connected to the aligner through spool 176. If there is a hole in M1 and no hole in position M2, then pressure will be applied to line 141 and spool 176 will remain up as shown. In that case, then fluid will pass through line 173 to the Y aligner via line 175. If on the other hand, M2 spool 176 is down because there is a hole in position M2 and pressure on line 142, then the pressure in line 173 will be coupled to θ output line 174. It should be noted that when spool 171 is down, that the line 172 is blocked by the upper spool land of spool 171. If there is no hole in position M1, then pressure will be applied on line 141 to hold spool 171 up thereby causing the lower land to block line 179 and permitting communication through the lower line 178. Line 178 communicates with the X aligner 181 as shown if there is no hole in position M2 and the spool 176 is up. If spool 176 is down, then the Z aligner line 180 would communicate with line 178. Lines 172 and 179 provide communication between the various portions of the system including line 116. When there is a hole in the M1 position, pressure will be applied to the left-hand side of the Z clamp valve 182. If, on the other hand, there is no pressure no hole in the M1 position and there is a hole in the M2 position, then pressure will be applied on line 142 to the right-hand end of the Z clamp valve 182. In such case, pressure from line 116 will be applied through Z clamp valve 182 and line 183 to the clamp piston 184 which is serrated to cooperate or engage with the Z beam clamp rack 185. This will occur only when there is pressure on line 142 of the 14-M2 latch valve and there is no pressure on the line 142 of latch valve 14-M1. The reason for this is that the Z clamp valve 182 includes a spring 186 which would unbalance an opposition of forces between the two lines 142. In other words, it would only occur when the Z aligner has been selected. Line 94 provides a drain to a lower pressure thereby releasing any one of the different aligners. Such release occurs only for one aligner at a time. In this way, the shaft 156 carrying the load may operate to drive only one of the members connected with one of the aligners at a time. The clamp piston is supposed to be engaged at all times except when the θ, Y, or X aligners are disengaged by connecting to the return R via line 94 during operation of the drive. The clamp piston is connected to the output of the drive shaft 156; and the Z beam clamp rack 185 is connected to the Z arm. The purpose of this is to provide protection against overload of the cable which is somewhat extensible and will vibrate in accordance with its elongation constant. It was desired to make the system stiffer and to reduce the vibration which would be occasioned by the extension and retraction of the cable when it was under a heavy load. Accordingly, this technique was employed.


in FIG. 2H, the latch valve 14 on the right-hand side is labelled sweep 14-S indicating that it is employed for controlling a unit used for sweeping the enitre manipulator which is being controlled by this system about a vertical axis. The support 190 for the sweep unit is shown in FIG. 2I in the lower left-hand corner. A support 190 is pivotable about an axis 191 under the driving force applied to pin 192 by shaft 193 by reciprocable sweep piston 194 in cylinder 195. Cylinder 195 has a counterclockwise input 196 and a clockwise input 197. When pressure is applied to line 198, it passes through orifice check 199 via line 196 to apply full pressure to the right side of piston 194 to drive the support 190 counterclockwise. On the other hand, pressure on line 200 passes through the orifice check valve 201 into the left-hand inlet 197 to drive the sweep piston 194 to pull the support 190 clockwise about the pivot 191. The sweep sense valve 202 is connected to line 25 in series with sweep sense valve 203. These sense valves perform two functions, one of which is to provide an auxiliary bleed exchange sense function. The move valve 69 may not operate until after the exchange sense valve 26 has closed its bleed due to termination of exchange; and similarly this series of sense valves requires that the sweep must be completed also before the drive motion of the piston adders is begun. This is provided simply by locating a land on each of these sweep sense valves 33 which when neither one of the extreme sweep positions have been reached will provide a short circuit from line 25 to the return 204 via line 205. Upon application of pressure to line 198, high pressure is applied to the right-hand end of the piston in the sweep sense valve 202 which was spring biased leftward by damping spring 210 which piston provides longitudinal force to the shaft 206. Such force is transmitted to bar 207 carried on the outboard edge of the support 190 to thereby give it an impulse to begin counterclockwise rotation. At the same time this will function to open up the connection of line 25 to return 204. As soon as the support 190 has reached its extreme home position in the counterclockwise direction, the bar 208 will drive the shaft 209 down along with the sweep sense valve 203 thereby closing the bleed via 25 and 205 to the return 204 and also driving the unit down against the damping spring 210 contained in the end of the sweep sense valve. Thus, the port 211 will be closed by the land of the valve 203 as it would be in the case of the valve 202 in the reverse direction of rotation, and this will mean that the short circuit path through the end of the valve will be closed and that the orifice check valve 201, as would the orifice check valve 199, will provide reduced flow through the orifice therein which is indicated by the orifice check symbol shown. Actually, an adjustable orifice and a check valve are connected in parallel for this purpose in order to provde a fairly low velocity flow rate of the sweep cylinder during its deceleration, as described in connection with FIG. 2C.

Hydraulic power supply

the hydraulic power supply 22 comprises an air engine 220 and an oil pump 221. The air engine includes a cylinder 222 and a piston 223 sealed by an O ring 224. A shaft 225 of the air piston 223 is hollow and contains a cylindrical bore 226 carrying a transfer piston 227 connected by a rod 228 through the coaxial bore 525 in the piston shaft 225 to the opposite side of the air piston 223 where it is secured by a rotating joint 229 to a first lever 230 provided at pin 231 secured to bracket 232 which is fastened to the housing of the air engine 220. Also pivoted on the pin 231 is a second lever 233 which carries at its opposite end a second rotating joint 234, secured to a shaft 235, carrying a spool valve referred to as a shuttle valve 236. A first lever 230 and the second lever 233, comprising a toggle bar, are interconnected by a compression spring 237 which will provide a toggle action between the two levers 230 and 233.

At the opposite end of shaft 225 is secured an oil piston 238 carrying an O ring 239 for reciprocation in a cylinder 240 coaxially aligned with the air cylinder 222. The oil pump 221 includes a screen 241, inlet valves 242 and 243, outlet 244 and 245, an outlet line 247 which supplies the fluid under pressure and an accumulator 248 for regulating the output pressure which would tend to vary in value as a function of the reciprocation of the pump. A source of air under pressure 249 is connected by line 250 to the inlet 251 and by land 252 to the passageway 253 into the space at the right end 254 of cylinder 222 exerting pressure on piston 223 to the left. Thus, the piston 233, rod 225, and the oil piston 238 will all be driven to the left and the oil in the space 255 to the left of the piston 238 will be compressed and exhausted through the outlet 244 into line 247. Simultaneously, oil will be admitted by valve 243 to the right hand side of piston 238. Air in space 256 to the left of the air piston 223 will be exhausted through line 259 to the outlet 258 from the air engine. As the piston assembly approaches the left-hand limit of its excursion, a transfer piston 227 will be struck by the surface 257 at the opposite end of cylindrical bore 226. In reaction to that impact, the transfer piston 227 and its drive rod 228 will be transferred to the left forcing the first lever 230 to snap counterclockwise until the bottom of the compression spring 237 will be transferred leftwardly forcing the second lever 233 to snap to the right pulling the shuttle valve 236 with it. Transfer of the shuttle valve 236 will apply air under pressure into space 256 confronting the left-hand surface of the air piston 223 and will permit the compressed air from the space 254 on the right-hand side of the air piston 223 to escape to the atmosphere through the lines 253 and 258. The sudden expansion of the air in line 258, as it passes from the air engine will cause the air to become very cool. Accordingly, secured to the exterior of the pipe 258 are a plurality of cooling vanes 260 for the purpose of cooling the hydraulic fluid which is contained in the space immediately surrounding the pump and air engine which space is suggested schematically by phantom line 8 in FIG. 2C. AT the opposite end of the air engine is an exhaust silencer 261 employed for the purpose of damping out vibrations of the exhausting air. The silencer 261 is connected to the atmosphere by means not shown. In the return reciprocation of the pistons to the right, oil under pressure will pass through valve 245 into the line 247, and oil from the reservoir will pass through screen 241 into inlet 242 and therefrom into the space 255 on the left-hand end of the cylinder 240. As the piston assembly approaches the right-hand limit of its excursion, the transfer piston 227 will be struck by the opposite end of the cylinder 226. The transfer piston and its drive rod will be driven to the right swinging the lever 230 clockwise until bottom of the compression spring 237 is driven to the right forcing the second lever 233 to snap to the left driving the valve 236 to the left with it. During the transfer period, the velocity of the oil piston 238 is either zero or close to zero for a period of time which is predominately dependent upon the transfer time constant, i.e., the rise and discharge time of the air pressure system. Therefore, it is important that the valve and air piston must be closely coupled with the exhaust circuit having minimum storage volume and a minimum restriction to flow. During this dwell time, the oil flow at the output is supplied entirely by the accumulator 248. The oil piston has a smaller diameter than the air piston. The air pressure supplied to the system is regulated by an external source. By selection of the ratio of oil piston diameter to air piston diameter, the output pressure of the hydraulic system may be selected. The velocity of the pump will vary as a function of the pressure on the output line relative to the maximum pressure which will be supplied when there is no drain on line 247 and full pressure has been reached. That is, the reciprocating frequency of the air oil piston assembly is dependent upon the oil flow demand and upon the pump output. Accordingly, pressure regulators and relief valves are not needed, so long as the air pressure supply is substantially constant in pressure.

Since the entire assembly is submerged in the oil reservoir 8, packing noise and cooling problems are all minimized. Mounts 280 and 281 are provided to support the air engine and pump on tank wall 8.

Orifice check 547 and accumulator 548 isolate line 116 from the wide fluctuations in pressure on line 47 as the result of displacement of the piston adders 15.

Z clamp, piston and rack

fig. 4 shows the Z arm 442 carried in the fixed frame 370. An endless drive cable 469 is shown passing around a pulley 369 and carried by shaft 372 extending through slot 371 in the fixed frame 370 and secured to the movable Z arm 442. The Z arm 442 carries a serrated rack (not shown) and above the rack is posed a toothed piston (not shown) within the cylinder 390. Items not shown herein are shown in detail in U.S. Pat. No. 3,575,301. The cylinder 390 operates to clamp and release the rack under control from a hydraulic line. The cylinder 390, its piston not shown and the rack (not shown) comprise the Z aligner which is connected to line 180 in FIG. 2E. The Z beam clamp rack cooperates with the clamp piston 184 which is operated inside of the cylinder 188, which is actuated by pressure in line 183 as described above. The cylinder 184 is carried about the slide connecter 367 which is secured to the upper end of the piston adder shaft 156. Extending from the slide connector 367 is the clamp bar 468 and a clamp 368 attached to the common drive cable 469.

The fixed frame 370 rides on a disc shaped support 190. This disc shaped support 190 is pivotally supported on a vertical shaft 191 for providing rotation of the fixed frame 370 to another position as indicated, in phantom, by line 444. A sweep cylinder 34 including its housing 195 and its actuation lines 196 and 197 is shown secured by a shaft 193 to the pivot 192. At the opposite end, it is pivotally secured to ground. The sweep sense valves 333 are shown located 90° apart for cooperation with the bar 207.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.