Synchronized computational architecture for generalized bilateral control of robot arms

• US 5,038,089 A
• Filed: 10/28/1988
• Issued: 08/06/1991
• Est. Priority Date: 03/23/1988
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Szakaly, Zoltan F.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ip, Paul
• Application Number:
  US07/264,326
• Time in Patent Office: 1,012 Days
• Field of Search: 318/567, 318/569, 318/568.11, 318/568.17, 318/568.20, 318/565, 318/566, 318/570-577, 364/513, 901/3, 901/6, 901/14, 901/19, 901/23
• US Class Current: 701/23
• CPC Class Codes: G05B 19/427 Teaching successive positions by tracking the position of a joystick or handle to control the positioning servo of the tool head, master-slave control G05B19/423 takes precedence
• CPC Class Codes: G05B 2219/40146 Telepresence, teletaction, sensor feedback from slave to operator
• CPC Class Codes: G05B 2219/40194 Force reflective, impedance shaping tele operation

Abstract

A master six-degree-freedom Force Reflecting Hand Controller ("FRHC") is available at a master site where a received image displays, in essentially real-time, a remote robotic manipulator which is being controlled in the corresponding six-degree-freedom by command signals which are transmitted to the remote site in accordance with the movement of the FRHC at the master site. Software is user-initiated at the master site in order to establish the basic system conditions and then a physical movement of the FRHC in Cartesean space is reflected at the master site by six absolute numbers that are sensed, translated, and computed as a difference signal relative to the earlier position. The change in position is then transmitted in that differential signal form over a high speed synchronized bilateral communication channel which simultaneously returns robot-sensed response information to the master site as forces applied to the FRHC so that the FRHC reflects the "feel" of what is taking place at the remote site. A system-wide clock rate is selected at a sufficiently high rate that the operator at the master site experiences the Force Reflecting operation in real time.

Claims

1. A universal computer control system having a control processor with a memory storage device that is software accessible, said control system characterized by being of master slave type for controlling a plurality of motors that can be controlled by a software program, with some motors of the plurality of said motors being located at a master site and some motors of the plurality of said motors being located at a remote site, and said system comprising:

a system code generator in signal communication with said memory storage device of said control processor for delivering thereto a predetermined code to be stored therein in order to electronically write a software control program for controlling said plurality of motors at both site locations;

a system software control program that is written electronically by said predetermined code issued from said system control generator;

means available to a user for inputting to said control processor a hardware configuration and operating parameters for each one of said plurality of motors to be controlled by said system software control program as written by said system; and

means responsive to said software control program written by said system and to said hardware configuration, and said operating parameters as input by the user into said control processor at said master site for emitting a plurality of command signals to control the operation of each one of said plurality of motors by said control processor.

2. A universal computer control system in accordance with claim 1 and further comprising:

means at said remote site sensing the system-software controlled operation of each one of said motors while they are being controlled for feeding back to said control processor a plurality of parameter signals indicative of the actual performance of each one of the controlled motors.

3. A universal computer control system in accordance with claim 2 and further comprising:

a converter at said master site for converting said feedback signals which are indicative of the motors parameters, to a format suitable for said control processor;

means feeding back said feedback signals from said converter to said control processor, whereby the feedback signals are computed as reflective force signals for said hand controller; and

means connecting the control processor to the hand controller for driving the hand controller at the master site with a reflected force according to said reflective force signals as an indication to the user of the action of the robotic manipulator at the remote site.

4. A universal computer control system in accordance with claim 3 and further comprising:

a signal bus interconnecting said control process at said master site for transmitting the command signals to the motors being controlled at said remote site, and

means also connecting said feedback signal emitting means at said remote site to said signal bus for feeding back signals as needed for force reflection at the master site.

5. A non-autonomous multiple-degree-freedom Force Reflecting Hand Controller ("FRHC") system at a master site where a received image displays to an operator, in essentially real-time, a remote robotic manipulator which is being controlled in a corresponding multiple-degree-freedom by command signals which are formulated at the master site for transmission to a remote site in accordance with an operator-controlled movement of the FRHC at the master site, said system comprising:

software, user-initiated at the master site and written by the system itself, in order to establish basic system operating conditions;

a first control processor means at the master site for translating an operator'"'"'s physical movement of the FRHC in Cartesean space into numbers indicative of relative movements of said FRHC in each degree of said multiple-degree-freedom, which numbers are formulated at said master site into said command signals for achieving a corresponding relative movement of said robotic manipulator at said remote site;

means for transmitting said command signals to said remote site for moving said robotic manipulator to a new and different commanded position relative to the robot'"'"'s earlier position; and

second processor control means at said remote site for returning to said master site, over said transmitting means, signals indicative of the robotic movements in order to provide a "feel" of those movements for the operator at the master site.

6. A system in accordance with claim 5 wherein a change in position in the robot at the remote site results from a difference in absolute positioning of said FRHC at said master site, and further comprising:

means at said master site for sensing the relative change in position of said FRHC;

said signal transmitting means is a high speed synchronized bilateral communication channel; and

means for converting that relative change of position of said FRHC to a differential signal form for transmission over said high speed synchronized bilateral communication channel.

7. A system in accordance with claim 6 and further comprising;

means for detecting in signal form, said change in position of said commanded robot manipulator at said remote site; and

means for supplying said signals indicative of said change in position to said second independent control processor.

8. A system in accordance with claim 7, wherein the control processors at each site are performing mathematically intense computations, and said system further comprising;

means for transmitting commands and returning robot-sensed response information to the master site at a sufficiently high rate that the FRHC reflects a "feel" of what is taking place at the remote site in essentially real time.

9. A system in accordance with claim 8 and further comprising;

means for emitting a system-wide clock signal, selected at said sufficiently high rate, that the operator at the master site may experience the operation of said commanded robot at said remote site in essentially real time in a force-reflecting mode for said master site; and

means for operating said system'"'"'s signal communication between both of said sites with said system-wide clock signal in order to provide said essentially real time operation.

10. A non-autonomous multiple-degree freedom Hand Controller ("HC") system at a master site where a received image displays, in essentially real-time, a remote robotic manipulator which is to be controlled in a corresponding degree-of-freedom by relative movement command signals which are formulated for transmission to a remote site in accordance with an operator'"'"'s command at the master site, said system including a first control system at the master site and a second control system at the remote site, and said "HC" system comprising:

software, operator-initiated at the master site and written by the system itself, in order to establish, at least in part, the command formulated by said first control system for transmission to said second control system at the remote site;

means translating operator-initiated movement of the HC in Cartesean space at the master site into a transmissible command signal that includes said software input and is indicative of relative movement of said HC in each of said degrees-of-freedom as desired for controlled system movement of said robotic manipulator at said remote site;

means associated with said first control system for transmitting said transmissible command signal to said second control system at said remote site; and

means in said second control system at said remote site for receiving said command signal transmitted from said master site and responsive thereto for moving said robot manipulator to a new and different commanded position, relative to the robot'"'"'s earlier position, which corresponds to the relative movement of the HC by the operator at the master site.

11. A system in accordance with claim 10 wherein a change in position of the manipulator at the robot site results from a relative difference as said HC is moved from one position to another at said master site, and further comprising:

means at said master site for sensing the amount of relative change in position of said HC; and

means for converting that relative change of position to a differential signal form for transmission over a high speed synchronized bilateral communication channel.

12. A system in accordance with claim 10 and further comprising;

means for detecting in signal form, said change in position of said commanded robotic manipulator at said remote site; and

means for transmitting said change of commanded position signal back to said master site in order to develope a "feel" at the HC at the commanded position change has taken place at the robotic manipulator.

13. A system in accordance with claim 12 wherein said means for transmitting is characterized as further comprising;

means for returning robot-sensed response information to the master site so that said HC reflects an image/"feel" in essentially real time of what is taking place at said robotic manipulator at the remote site.

14. A system in accordance with claim 13 and further comprising;

means for emitting a system-wide clock signal, selected at a sufficiently high rate, that the operator at the master site may experience the operation of said commanded robot at said remote site in essentially real time in a force-reflecting mode for said HC at said master site; and

means for operating said system'"'"'s signal communication between both of said sites over said high speed communication channel at said system-wide clock signal rate in order to provide said essentially real time operation.

15. A method of controlling a multiple-degree-freedom Force Reflecting Hand Controller ("FRHC") at a master site where a received image displays, in essentially real-time, a remote robotic manipulator which is to be controlled in a corresponding degree-of-freedom by operator-formed command signals which are formulated for transmission to a remote site in accordance with an operator'"'"'s command at the master site, said method comprising:

operating software at the master site, in order to establish, at least in part, a desired command for the remote site;

writing said operating software by the system itself;

translating relative movement of the FRHC in Cartesean space at the master site into a transmissible command signal that includes said software input and is indicative of a desired degree-of-freedom movement for said manipulator at said remote site; and

transmitting said transmissible command signal to said remote site for moving said robot manipulator to a new and different commanded position relative to the robot manipulator'"'"'s earlier position.

16. A method in accordance with claim 15 wherein a change in position of the manipulator at the robot site results from a difference in absolute positioning of said FRHC at said master site, and further comprising:

sensing the relative change in position of said FRHC at said master site;

converting that relative change of position to a differential form for transmission to said remote site;

transmitting that signal in differential form to the remote site;

receiving the transmitted signals at the robot'"'"'s control system located at the remote site; and

slowly and smoothly moving the remote manipulator in accordance with the received signals.

17. A method in accordance with claim 16 and further comprising;

detecting, in signal form, said change in actual position of said commanded robot manipulator at said remote site; and

returning said detected signal to the master site as a reflection of the action taken at the remote site.

18. A method in accordance with claim 17 and further comprising;

returning robot-sensed response information to the master site;

converting, in essentially real time, the returned information into a FRHC resistance that reflects an "feel" of what is taking place to said manipulator at the remote site; and

displaying, for an operator at the master site also in essentially real time, the robot'"'"'s movements at the remote site.

19. A method in accordance with claim 15 and further comprising;

instituting a force-reflecting mode for said FRHC at the master site; and

operating said system at both of said sites in essentially real time so that the FRHC reflects the remote manipulator'"'"'s actual response.

20. A method in accordance with claim 15, wherein intense hardware/software controlling computations are required at each site;

and said method comprises the additional steps of;

performing such computations by interrupt-driven servo loops; and

operating said servo loops over a bilateral transmission control that connects the master site with the slave site.

21. A method in accordance with claim 20 characterized by interrupt driven software combined with hardware synchronism, and further wherein said step of performing said computations includes the substeps of:

synchronizing said computational capabilities at both sites by a common clock; and

operating said servo loops over a balanced load on the bilateral communication channel that interconnects the two sites.

22. A method in accordance with claim 20 including kinematic and dynamic relations between the master and robot arms, and including the further step of;

embedding mathematical transformations in computer programs in both the master and the remote sites; and

controlling the remote and the master site robots by the mathematical transformations embedded in said computer programs.

23. A method in accordance with claim 22 wherein forward and inverse kinematic computations, necessary for controlling a robotic manipulator, comprising the substeps of;

performing at the remote site by a forward kinematic ("FK") processor and an inverse kinematics ("IK") processor.

24. A method in accordance with claim 23 and further comprising the additional step of:

connecting both the "FK" and the "IK" processors to a multibus system; and

providing a shared memory to be used by the "FK" and the "IK" processors.

25. A method in accordance with claim 24 wherein a joint command processor ("JOINT") responds to the "IK" processor, and said method is further comprising the steps of:

sensing the FRHC-commanded actual movements of the robot; and

feeding back signals indicative of that sensed movement to the master site over said bilateral communication channel.

26. A method in accordance with claim 25 wherein said sensed signals are received at the master site after being transmitted over said communication channel, and said method includes the further steps of:

transforming the received signals at the master site to forces of "feel" for the operator in the FRHC at the master site.

27. A method in accordance with claim 26 and further comprising the additional steps of:

presenting at the master site for said operator a visual record of the controlled manipulator'"'"'s movements; and

supplying the visual record in essentially real time while the operator can sense resisting forces on the FRHC as a reflected "feel" of the control over the robot'"'"'s movements at the remote site.