Dynamic simulation of a hydraulic exoskeleton robot based on virtual prototyping

Abstract

The exoskeleton robot enhances the wearer's strength and plays an important role in various applications such as disaster relief, battlefield, rehabilitation, etc. The hydraulic system is often used to actuate the locomotion robotics for the advantages of high power-to-mass ratio, large force output, and so on. In this paper, the dynamic simulation of a hydraulic-driven exoskeleton robot is presented. Based on virtual prototyping, the controller and the parameters of the hydraulic system are determined and verified by modeling the driven system in AMESim, while the robot dynamic behavior is analyzed by building the robot dynamic model in ADAMS. The model of the prime mover, an IC engine, is simplified to reflect its torque-speed property rather than the complicated physical and chemical changes in the combustion cycle. In the simulation, the controller is determined first by employing a sufficient constant flow source to replace the engine model and the pump. Then the parameters of the hydraulic system are verified based on the determined controller. Lastly, the dynamic behavior of the exoskeleton robot is predicted by tracking the input reference from the Clinical Gait Analysis (CGA) data. The simulation results indicate that the designed exoskeleton robot can achieve expected working conditions. Experiments are set up on the exoskeleton robot prototype to validate the virtual prototype. The agreement of the results from simulation and experiments confirms that the virtual prototype predicts the dynamic behavior of the exoskeleton robot reliably.