Force-reflective teleoperation control system

• US 5,072,361 A
• Filed: 02/01/1990
• Issued: 12/10/1991
• Est. Priority Date: 02/01/1990
• Status: Expired due to Fees

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: Sarcos Group
• Inventors: Biggers, Klaus B., Iversen, Edwin K., Jacobsen, Stephen C., Davis, Clark C.
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): Gordon, Paul
• Application Number:
  US07/473,575
• Time in Patent Office: 677 Days
• Field of Search: 364/167.01, 364/513, 364/424.01, 364/559, 364/132, 364/190, 414/2, 414/4, 414/5, 414/6, 414/909, 623/57, 901/23, 901/45, 318/568.17
• US Class Current: 700/65
• 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 2219/37396 Tactile feedback, operator feels reaction, force reflection

Abstract

A teleoperation system includes a master station having a manually operable master link coupled to a master actuator which provides force resistance to operation and movement of the master link, and a slave station having a slave link moveable by a slave actuator in response to command signals. The system also includes a control unit for producing command signals in response to movement of the master link, such control unit having a position transducer for producing signals representing the position of the master link, a force transducer for producing signals representing the force applied to the master actuator by operation of the master link, a second force transducer for producing signals representing force applied to the slave link by the slave actuator, a second position transducer for producing signals representing position of the slave link, and a force controller responsive to the master link position signal, the master actuator force signal, the slave actuator force signal and the slave link position signal for producing a force command signal for supply to the slave actuator to cause the slave actuator to move the slave link in substantially faithful imitation of movement of the master link.

Claims

1. In a teleoperation system having a master station, which includes an operable master link coupled to a master actuator which provides force resistance to operation and movement of the master link in response to command signals, and a slave station, which includes a slave link moveable by a slave actuator in response to command signals, a control system for producing command signals in response to movement of the master link comprising:

means for producing a signal representing position of the master link;

means for producing a signal representing force applied to the master actuator by operation of the master link;

means for producing a signal representing force applied to the slave link by the slave actuator;

means for producing a signal representing position of the slave link; and

first force control means responsive to the master link position signal, the master actuator force signal, the slave actuator force signal, and the slave link position signal for producing a first force command signal for supply to the slave actuator to cause the slave actuator to move the slave link in substantially faithful imitation of movement of the master link.

2. A control system as in claim 1 further including second force control means responsive to the master link position signal, the master actuator force signal, the slave actuator force signal, and the slave link position signal for producing a second force command signal for supply to the master actuator to cause the master actuator to resist movement of the master link in substantially faithful imitation of the force resistance encountered by the slave link.

3. A control system as in claim 2 wherein said first force control means and said second force control means each comprises means for producing a signal indicative of the sum of differences between the position of the slave link and the position of the master link, and between the force supplied by the slave actuator to the slave link and the force encountered by the master link from the master actuator.

4. A control system as in claim 3 wherein said first force control means comprises

a slave position servocontrol mechanism for producing a first position difference signal representing the difference between the position of the slave link and that of the master link, and for amplifying the first position difference signal;

a slave force servocontrol mechanism for producing a first force difference signal representing the difference between the force supplied by the slave actuator to the slave link and the force encountered by the master link from the master actuator, and for amplifying the first force difference signal; and

first summing means for summing the first position difference signal and the first force difference signal to produce the first force command signal.

5. A control system as in claim 4 wherein said second force control means comprises:

a master position servocontrol mechanism for producing a second position difference signal representing the difference between the position of the master link and that of the slave link, and for amplifying the second position difference signal;

a master force servocontrol mechanism for producing a second force difference signal representing the difference between the force encountered by the master link from the master actuator and the force supplied by the slave actuator to the slave link, and for amplifying the second force position difference signal, and

second summing means for summing the second position difference signal and the second force difference signal to produce the second force command signal.

6. A control system as in claim 5 further comprising differentiation means for producing a signal representing the rate of change of the slave actuator force signal, and threshold means for supplying a threshold signal to the master actuator to cause it to momentarily apply a force to the master link when the rate of change signal exceeds a certain threshold level.

7. A control system as in claim 6 wherein said threshold signal comprise a short-duration pulse signal supplied to the master actuator.

8. A control system as in claim 1 further including means for supplying the first force command signal to the master actuator to cause the master actuator to resist movement of the master link in substantially faithful imitation of the force resistance encountered by the slave link.

9. A control system as in claim 8 wherein said first force control means comprises

a position servocontrol circuit responsive to the master link position signal and the slave link position signal for producing a position difference signal representing the difference between the position of the master link and the position of the slave link,

a force servocontrol circuit response to the master actuator force signal and the slave actuator force signal for producing a force difference signal representing the difference between the force encountered by the master link from the master actuator, and the force supplied by the slave actuator to the slave link, and

a summing circuit for summing the position difference signal and the slave difference signal to produce the first force command signal.

10. A control system as in claim 9 further comprising differentiation means for producing a signal representing the rate of change of the slave actuator force signal, and threshold means for supplying a threshold signal to the master actuator when the rate of change signal exceeds a predetermined threshold level, and wherein said master actuator is adapted to abruptly increase the resistance to movement of the master link in response to the threshold signal.

11. A control system as in claim 10 wherein said threshold means comprises means for producing a high frequency signal pulse for application to the master actuator to cause it to briefly increase the resistance to movement of the master link.

12. A teleoperation control system comprising

a master station including

a manually moveable master element,

a master actuator means coupled to the master element for presenting a force resistance to movement of the master element in response to a master command signal,

master position transducer means for producing a master position signal representing position of the master element, and

master force transducer means for producing a master force signal representing force applied to the master actuator means by the master element when the master element is moved, and

a slave station including

a moveable slave element,

a slave actuator means coupled to the slave element and responsive to a slave command signal for causing the slave element to move,

slave position transducer means for producing a slave position signal representing position of the slave element, and

slave force transducer means for producing a slave force signal representing force applied by the slave actuator means to the slave element,

said master station further including

master position control means responsive to the master position signal and slave position signal for producing a first error signal representing the difference in position of the master element and slave element,

master force control means responsive to the master force signal and slave force signal for producing a second error signal representing the difference in force applied by the master element to the master actuator and force applied by the slave actuator to the slave element, and

master summing means for adding the first and second error signals to produce a master command signal for application to the master actuator to cause the master actuator to vary the force resistance to movement of the master element in accordance with the value of the master command signal, and

said slave station further including

slave position control means responsive to the master position signal and slave position signal for producing a third error signal representing the difference in the position of the master element and slave element,

slave force control means response to the master force signal and slave force signal for producing a fourth error signal representing the difference in force supplied by the master element to the master actuator and force supplied by the slave actuator to the slave element, and

slave summing means for adding the third and fourth error signals to produce a slave command signal for application to the slave actuator to cause the slave actuator to move the slave element in accordance with the value of the slave command signal.