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Hybrid constraint space position/force control

University of British Columbia

This thesis documents the conceptual development of the author's contribution, the hybrid constraint space position/force controller for robotic manipulator control in constrained environments. This method is built upon a constraint space dynamic model, where the model parameters are displacement along the constraint trajectory and normal force between the manipulator end-effector and environment. This dynamic model is constructed by transforming conventional joint space manipulator dynamics into their constraint space equivalents through the application of mapping functions, which relate differential displacements and velocities in the constraint space coordinate system to the joint space coordinate system. Conventional PD controllers may then be applied to the simplified dynamic structure of the constraint space equations of motion, in order to produce a vector of manipulator joint torques which will satisfy both position and force requirements along the environmental constraint. Actuator constraints and momentum compensating techniques are also used to ensure that the position and force control problems are completely decoupled from one another. This modelling technique is then applied to the control problem for a two degree of freedom prismatic robot as an illustrative example. Simulation of this specific controller is carried out with respect to three different constraint surfaces, a planar, a concave circular and a convex circular environment. The results of these simulations show that the hybrid constraint space controller provides excellent position and force trajectory tracking for the planar case study. This thesis is intended to be the forerunner to future work which will develop in detail, the application of hybrid constraint space control to highly nonlinear manipulator/constraint models.

Thesis/Dissertation

application/pdf

2009-02-16

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http://hdl.handle.net/2429/4630

Mechanical Engineering

University of British Columbia

UBCV

DSpace