Coordinated joint motion control system

• US 7,457,698 B2
• Filed: 09/03/2002
• Issued: 11/25/2008
• Est. Priority Date: 08/31/2001
• Status: Expired due to Fees

• Current Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Original Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Inventors: Danko, George
• Primary Examiner(s): Tran; Khoi H.
• Assistant Examiner(s): Kiswanto; Nicholas
• Application Number:
  US10/488,011
• Publication Number:
  US 20040267404A1
• Time in Patent Office: 2,275 Days
• Field of Search: 701/50, 701/2, 700/45, 700/69, 700/85, 700/65, 414/1, 374/14, 374/45, 379/06, 379/07, 901/8
• US Class Current: 701/50
• CPC Class Codes: B25J 9/1607 Calculation of inertia, jacobian matrixes and inverses
• CPC Class Codes: B25J 9/1651 acceleration, rate control
• CPC Class Codes: E02F 3/437 providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant
• CPC Class Codes: E02F 3/438 Memorising movements for repetition, e.g. play-back capability
• CPC Class Codes: E02F 3/439 Automatic repositioning of the implement, e.g. automatic dumping, auto-return E02F3/438 takes precedence
• CPC Class Codes: E02F 9/2037 Coordinating the movements of the implement and of the frame
• CPC Class Codes: E02F 9/2041 Automatic repositioning of implements, i.e. memorising determined positions of the implement for dipper-arms or bucket-arms E02F3/434, E02F3/437, E02F3/438, E02F3/439 take precedence
• CPC Class Codes: G05B 2219/39062 Calculate, jacobian matrix estimator
• CPC Class Codes: G05B 2219/39224 Jacobian transpose control of force vector in configuration and cartesian space
• CPC Class Codes: G05B 2219/40495 Inverse kinematics model controls trajectory planning and servo system

Abstract

A coordinated joint control system for controlling a coordinated joint motion system, e.g an articulated arm of a hydraulic excavator blends automation of routine tasks with real-time human supervisory trajectory correction and selection. One embodiment employs a differential control architecture utilizing an inverse Jacobian. Modeling of the desired trajectory of the end effector in system space can be avoided. The invention includes image generation and matching systems.

Claims

1. A coordinated joint control system for controlling a coordinated joint motion system, the coordinated joint motion system comprising:

a) a support system;

b) an end effector movable relatively to the support system by the coordinated joint motion system;

c) multiple links to link the end effector to the support system;

d) multiple joints connecting the multiple links one to another, to the support system and to the end effector, each joint permitting relative movement between two adjacent ones of the members connected together by the respective joint;

e) multiple actuators to effect said relative movement between the connected members, the multiple actuators being controlled by the coordinated joint control system; and

f) an operator interface comprising at least one manually movable control member to input human operator-provided control signals to the control system;

wherein the coordinated joint control system comprises;

i) a menu of virtual kinematics configurations selectable through the operator interface, each virtual kinematics configuration comprising a family of trajectory paths of the end effector, each trajectory path being configured in at least two dimensions;

ii) a model-based forward predictor to provide velocity components for operation of the coordinated joints to move the end effector according to a selected virtual trajectory family in differential form;

iii) control connections between the operator interface and the model-based forward predictor to modify the coordinated joint velocity components of the virtual machine according to operator input; and

iv) a differential control kinematics generator to generate a position-dependent differential inverse kinematics model of the coordinated joint motion system and to distribute to the multiple joint actuators coordinated control signals comprising the modified coordinated joint velocity components provided by the model-based forward predictor.

2. A control system according to claim 1 comprising an internal feedback loop to determine the differential inverse kinematics model of the coordinated joint motion system and provide the model-based forward predictor.

3. A control system according to claim 1 wherein link position control is based on the Cartesian acceleration components of the multiple links.

4. A control system according to claim 1 wherein the control system comprises a control computer and operates without generating an integrated path in control computer model-space, and differentiating the trajectory for joint variable control during real-time machine control, optionally without requiring internal joint position control loops.

5. A control system according to claim 1 wherein the coordinated joint motion system comprises a mining or construction machine, optionally an excavator.

6. A control system according to claim 5 wherein the multiple links comprise a boom revolutely connected to the machine, an arm revolutely connected to the boom and a work tool revolutely connected to the arm.

7. A control system according to claim 1 wherein the multiple joints are revolute joints or prismatic joints.

8. A coordinated joint motion system comprising a control system according to claim 1.

9. A coordinated joint control system according to claim 1, wherein the selected virtual kinematics configuration is connected to an artificial intelligence module for adjustment and optionally for optimization of the virtual kinematics configuration for a work environment or work condition or both a work environment and a work condition.

10. A coordinated joint control system according to claim 1, wherein the selected virtual kinematics configuration is connected to at least one external motion or position sensor to adjust and, optionally, optimize the virtual kinematics configuration for a work environment or a work condition or both a work environment and a work condition.

11. A real-time control method for controlling a coordinated joint motion system, the coordinated joint motion system comprising:

a) a support system;

b) an end effector movable relatively to the support system by the coordinated joint motion system;

c) multiple links to link the end effector to the support system;

d) multiple joints connecting the multiple links one to another, to the support system and to the end effector, each joint permitting relative movement between two adjacent ones of the members connected together by the respective joint;

e) multiple actuators to effect said relative movement between the connected members, the multiple actuators being controlled by the coordinated joint control system; and

f) an operator interface comprising at least one manually movable control member to input a human operator-provided control signal to the control system;

wherein the control method comprises;

i) operating the operator interface to select a virtual kinematics configuration, from a menu of virtual kinematics configurations each virtual kinematics configuration comprising a family of trajectory paths of the end effectorconfigured in at least two dimensions;

ii) calculating velocity components for operation of the coordinated joints to move the end effector according to the selected virtual kinematics configuration using a model-based forward predictor;

iii) determining the joint velocity components of the virtual machine from the control signal received from the operator interface and the model-based forward predictor; and

iv) generating a position-dependent, differential inverse kinematics model of the coordinated joint motion system and

v) distributing coordinated control signals comprising the coordinated joint velocity components determined by the model-based forward predictor and the differential inverse kinematics generator.

12. A method according to claim 11 comprising relating the joint-space variables as a vector, to an input vector of Cartesian variables employing an inverse Jacobean matrix.

13. A method according to claim 11 comprising employing the Cartesian acceleration components of the multiple links to control the end effector position.

14. A method according to claim 11 comprising differentiating the trajectory for joint variable control during real-time machine control without requiring internal joint position control loops and without generating an integrated path in control computer model-space.

15. A method according to claim 11 comprising applying each motion component to the joint actuators employing a Cartesian position control loop and visual feedback from the human supervisor.

16. A method according to claim 11 wherein the at least one manually movable member comprises multiple joysticks and the method comprises distributing a control signal from a single one of the joysticks to at least two of the multiple joint actuators.

17. A method according to claim 11 performed on a mining or construction machine.

18. A real time control method according to claim 11, wherein the selected virtual kinematics configuration, comprising a family of trajectory paths in differential form is adjusted and optionally optimized for a work environment or work condition or both work environment and a work condition by an output decision received from an artificial intelligence module by modifying the virtual kinematics configuration.

19. A real-time control method according to claim 11, comprising adjusting and, optionally, optimizing the selected virtual kinematics configuration for a work environment or work condition, or both a work environment and a work condition, by the output of at least one external motion or position sensor the output of the at least one motion or position sensor being employed to modify the virtual kinematics configuration.

20. A real-time control method according to claim 11 comprising recording the end effector trajectory during execution of the end effector trajectory by the control system and adding the recorded trajectory to the menu of virtual kinematics configurations.

21. A real-time control method according to claim 11 wherein the control system employs an artificial intelligence component to review the menu of virtual kinematics configurations and determining and selecting an appropriate virtual kinematics configuration for a particular coordinated joint motion system task.