Nonlinear feedback control of two manipulators in presence of environmental constraints

The coordinated control of two manipulators in the presence of environmental constraints is studied. Such a control method is needed in applications in which the two manipulators grasp a common object and move it along a surface while exerting a certain amount of contact force. The two manipulators constrain each other and are also constrained by the environment. It is observed that the motion and constraint equations obtained directly from mechanics are not suitable for control purposes. A set of equivalent equations is derived in the standard nonlinear system representation with clear state equations and output equations. A nonlinear feedback that linearizes and decouples the dynamic nonlinear system of the two constrained manipulators is found. The coordinated controller design is then carried out for the linearized system