Investigation of hardware-in-the-loop walking/running test with spring mass system

Abstract

Hardware-in-the-Loop (HIL) testing has been used successfully for a number of years on a wide range of applications. Any delay in actuation systems will increase the system energy if it is not properly compensated for due to the negative damping effect. A HIL walking/running testing system has advantages for testing lower-limb prosthetics over traditional human-based testing, i.e. safer, more objective. However, the stiff ground contact discontinuity is hard to compensate. This paper investigates the effect of introducing nonlinearity and discontinuity into a HIL system by comparing three types of Spring Mass System. Also, a requirement on the HIL testing actuation system is concluded that the actuation system delay frequency should be 20 times greater than the system natural frequency in order to keep the system simulation stable.