Input Shaping Using Finite Impulse Response Filters

The use of input shapers in control system design helps to decrease the overshoot and the settling time of underdamped dynamic systems. This paper discusses the use of finite impulse response (FIR) filters as input shapers for under-damped systems. Three specific FIR filters were studied. These include: the boxcar, the triangle, and the half sinusoid. The three filter responses were compared to a normal step response, as well as a step response with a low-pass filter as a pre-filter. The comparisons were performed on a 2nd order system simulated in Matlab/Simulink simulation software package as well as on a piezo-actuated fast responding stage. The data shows that the FIR filter can significantly improve the response of the system both in simulation and experimentally. The triangular FIR filter was particularly effective in the actual hardware implementation