Improved reset control design for a PZT positioning stage

Reset control was studied for enhanced performance that can not be obtained by linear controllers. The conventional reset control is simple for implementation by resetting some of its controller states to zero when its input is zero. However, we find that in some cases the performance of conventional reset control is still limited such as only partial reduction of the overshoot. Thus, this paper presents the stability analysis and design of an improved reset control system, where the reset times are prespecified and the controller states are reset to certain non-zero values, which are calculated online in terms of the system states for optimal performance. Experimental results on a PZT microactuator positioning stage show that the improved reset control can completely remove the overshoot and thus achieve shorter settling time than the conventional reset control. Moreover, robustness tests against various step levels, disturbance and sensor noise are presented.