Hardware-in-loop simulation of robots interacting with environment via algebraic differential equation

Hardware-in-the-loop simulation is an attractive tool to validate the functionality of space robots. It is the purpose of the hardware-in-the-loop simulation to make a rigid robot prototype behave, in contact/noncontact phases, as closely as possible to a given robot reference model that would be encountered in the real-world. We introduce a method for the hardware-in-the-loop simulation that is based on the projection of the generalized coordinates of the robot model into two subspaces representing independent and dependent coordinates. The independent coordinate is obtained via simulation by making use of its acceleration model expressed in a closed form. While, the dependent coordinate is obtained from the generalized coordinated of the linearized robot prototype acting as a double integrator on the input dependent-coordinate acceleration. It is followed by investigating the effect of external disturbance on the performance of the hardware-in-the-loop simulation, by the method of Lagrangian multiplier. Finally experimental results obtained from implementation of a single axis arm is presented.