Method to control a robot device and robot device

• US 8,924,010 B2
• Filed: 02/11/2010
• Issued: 12/30/2014
• Est. Priority Date: 02/13/2009
• Status: Active Grant

• Current Assignee: Hocoma AG (DIH Technologies Co.), ETH Zurich
• Original Assignee: Hocoma AG (DIH Technologies Co.)
• Inventors: Riener, Robert, Vallery, Heike, Duschau-Wicke, Alexander
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): RINK, RYAN J
• Application Number:
  US13/320,694
• Publication Number:
  US 20120130538A1
• Time in Patent Office: 1,783 Days
• Field of Search: 601/5, 601/33
• US Class Current: 700/245
• CPC Class Codes: B25J 9/1638 compensation for arm bending/inertia, pay load weight/inertia
• CPC Class Codes: G05B 19/423 Teaching successive positions by walk-through, i.e. the tool head or end effector being grasped and guided directly, with or without servo-assistance, to follow a path
• CPC Class Codes: G05B 2219/36429 Power assisted positioning
• CPC Class Codes: G05B 2219/45109 Excercise, coordination, therapy, rehabillitation robot for disabled patients
• CPC Class Codes: G05B 2219/45112 Arm movement aid
• CPC Class Codes: Y10S 901/02 Arm motion controller

Abstract

A method to control a robot device that includes at least one manipulator which is moveable in an operating space, at least one actuator which actuates the manipulator, a sensor arrangement having at least one position sensor to determine the actual position of the manipulator and a controller which controls the actuator. The manipulator moves along an actual trajectory by means of an external force provided by an operator. The actuator provides compensation forces onto the manipulator influencing the torques or forces exchanged between operator and manipulator. The controller includes a conservative force field module having a conservative force field. The controller provides control signals for the actuator which provides the compensation force based on the control signals. The control signals are based on the conservative force field and on the actual position of the manipulator.

Claims

1. A method to control a robot device which comprises at least one manipulator which is moveable in an operating space, at least one actuator which actuates said manipulator, a sensor arrangement having at least one position sensor to determine an actual position of the manipulator and a controller which controls said actuator, the method comprising:

moving said manipulator along an actual trajectory by means of an external force provided by an operator;

providing compensation forces from the actuator onto the manipulator influencing torques or forces exchanged between the operator and manipulator;

defining a conservative force field with a conservative force field module of the controller by the steps of;

defining at least one predefined trajectory in the operating space;

creating a force field based on positions of the manipulator in the operating space on said predefined trajectories and based on at least one of the group comprising the velocities of the predefined trajectories and the accelerations of the predefined trajectories; and

calculating a conservative force field based on, said force field as a function of the position of the manipulator, wherein the conservative force field serves to determine control signals; and

providing control signals from the controller for said actuator which provides said compensation forces based on the control signals,

wherein the control signals are based on the conservative force field and on the actual position of the manipulator.

2. The method according to claim 1, wherein the conservative force field is further based on a calculation of needed torques as a function of and at least one of the group comprising the position, the velocities and the accelerations;

and

wherein an optimization of the compensation forces is conducted to determine the conservative force field as a function of the position, such that the difference between the compensation forces and the needed torques is as dose as possible to desired interaction torques.

3. The method according to claim 1, wherein undefined areas in the operating space having undefined velocities and at least one of the group comprising undefined accelerations and undefined needed torques, will be filled by means of at least one of the group comprising interpolation fit and extrapolation fit under the criteria of the conservative force field.

4. The method according to claim 1, wherein overdefined areas in the operating space having overdefined velocities and at least one of the group comprising overdefined accelerations and overdefined needed torques, are included in the optimization, leading to at least one of the group comprising compromise behavior and average behavior, or leaving underdefined areas that can again be filled using at least one of the group comprising interpolation and extrapolation.

15. The method according to claim 1, wherein overdefined areas in the operating space having overdefined velocities and at least one of the group comprising overdefined accelerations and overdefined needed torques, are included in the optimization, using at least one of the group comprising interpolation and extrapolation.

5. A robot device comprising:

at least one manipulator which is moveable in an operating space;

at least one actuator which actuates said manipulator;

a sensor arrangement having at least one position sensor to determine an actual position of the manipulator; and

a controller which controls said actuator;

wherein said manipulator is moveable along an actual trajectory by means of an external force provided by an operator;

wherein said actuator provides compensation forces onto the manipulator influencing the interaction torques or forces exchanged between operator and manipulator;

wherein the controller comprises a conservative force field module comprising a conservative force field which is defined by a method comprising the steps of defining at least one predefined trajectory in the operating space;

creating a force field based on positions of the manipulator in the operating space on said predefined trajectories and based on at least one of the group comprising the velocities of the predefined trajectories and the accelerations of the predefined trajectories; and

calculating the conservative force field based on said force field or forces, respectively as a function of the position of the manipulator, wherein the conservative force field serves to determine control signals allowing compensation of robot dynamics and other additional functions, such as assistance;

wherein the controller provides said control signals for said actuator, which provides said compensation force based on the control signals,

wherein the control signals are based on the conservative force field and on the actual position of the manipulator.

6. The robot device according to claim 5, wherein the conservative force field module is a static function of position, which can be encoded in a look-up table comprising at least one of the group of corresponding position data and corresponding force data or in an arithmetic function.

7. The robot device according to claim 5, wherein the predefined trajectory is defined as at least one trajectory within the operating space of the manipulator and the predefined trajectory comprises crossing or bifurcations, wherein the operator chooses along which path it shall be followed.

8. The robot device according to claim 5, wherein the sensor arrangement comprises a force sensor.

9. The robot device according to claim 5, wherein the dynamics, including at least one of the group comprising an inertia of the manipulator and parts of an inertia of the operator, are compensated by means of the actuator.

10. The robot device according to claim 5, wherein the conservative force field is specifically determined for a specific trajectory of an operator and its requirements concerning compensation of dynamics of the manipulator.

11. The robot device according to claim 5, wherein the spatial dimension of the movement of the manipulator is limited by parameters.

12. The robot device according to claim 5, wherein the manipulator comprises at least one connection point to which the operator is connectable.

13. The robot device according to claim 5, wherein the manipulator is fixed with regard to at least one degree of freedom.

14. The robot device according to claim 5, wherein the compensation force provided by the actuator has a value which enables movement of the manipulator with aid of the operator.

16. The robot device according to claim 5, wherein the predefined trajectory is defined as a single trajectory or as a plurality of different trajectories within the operating space of the manipulator or the predefined trajectory comprises crossing or bifurcations, wherein the operator chooses along which path it shall be followed.