Delay time compensation for a hybrid simulator

A hybrid simulation, which is also referred to as a hardware-in-the-loop (HIL) simulation, includes a hardware experiment within a numerical simulation loop. The hybrid simulation is an effective method to test space robotic operations providing a virtual microgravity environment on the ground. However, hybrid simulation generally suffers from the problem of energy increase when two hardwares in the loop collide with each other because of delay times. This paper presents a compensation method for the energy increase problem. A dead time model that represents various delay times of the system is introduced and it is clarified how the energy of the system is increased by the dead time. Based upon the dead time model, a compensation for the dead time is proposed. This compensation method realizes the desired energy consumption at a collision, which is represented by the coefficient of restitution in the hybrid simulation. Experiments of uniaxial collision are conducted to validate the proposed compensation.