Learning friction estimation for sensorless force/position control in industrial manipulators

We present a novel type of friction estimation applied to the field of sensorless force/position control. As part of a position based neural force control (NFC-P) the estimation friction and external force allows a force/position control without using a force sensor. NFC-P consists of a hybrid force/position controller that accurately generates contact forces to objects with arbitrary flexibility and uncertain distance or shape. NFC-P performs force control by modifying the desired joint angle changes in force direction before they are fed into a computed torque controller. The inverse dynamics of the manipulator is modeled in a computed torque controller. Kinematic mappings guarantee singularity robustness in the entire workspace. Results from real time experiments are presented with a 6-DOF industrial manipulator as a testbed.

[1]  Rolf Eckmiller,et al.  Hard contact surface tracking for industrial manipulators with (SR) position based force control , 1999, Proceedings 1999 IEEE International Conference on Robotics and Automation (Cat. No.99CH36288C).

[2]  Rolf Eckmiller,et al.  How to compensate stick-slip friction in neural velocity force control (NVFC) for industrial manipulators , 1999, Proceedings 1999 IEEE International Conference on Robotics and Automation (Cat. No.99CH36288C).

[3]  James E. Steck,et al.  Linear and neural network feedback for flight control decoupling , 1996 .

[4]  Paolo Rocco,et al.  On the Stability of Integral Force Control in Case of Contact With Stiff Surfaces , 1995 .

[5]  Rajiv V. Dubey,et al.  Variable damping impedance control of a bilateral telerobotic system , 1996, Proceedings of IEEE International Conference on Robotics and Automation.

[6]  Rolf Eckmiller,et al.  Neural force control (NFC) applied to industrial manipulators in interaction with moving rigid objects , 1998, Proceedings. 1998 IEEE International Conference on Robotics and Automation (Cat. No.98CH36146).

[7]  Dragoljub Surdilovic,et al.  Contact stability issues in position based impedance control: theory and experiments , 1996, Proceedings of IEEE International Conference on Robotics and Automation.

[8]  R. E. Eckmiller,et al.  Neural Trajectory Optimization (NTO) for Manipulator Tracking of Unknown Surfaces , 1998 .

[9]  Robert G. Bonitz,et al.  Robust internal-force based impedance control for coordinating manipulators-theory and experiments , 1996, Proceedings of IEEE International Conference on Robotics and Automation.

[10]  Nariman Sepehri,et al.  Position-based impedance control of an industrial hydraulic manipulator , 1996, Proceedings of IEEE International Conference on Robotics and Automation.