Design, testing and precision control of a novel long-stroke flexure micropositioning system

• A micropositioning stage with both long stroke and compact size is devised.
• A new discrete-time sliding mode control algorithm is proposed.
• Stage parameter optimization and structure improvement are performed.
• Finite-element analysis and experimental studies are carried out.
• A submicron resolution over 11 mm stroke is achieved.

This paper presents the design, modeling, analysis, testing and control of a novel compact long-stroke precision positioning stage. The stage is devised with leaf flexures to achieve a submicron-accuracy positioning with a stroke longer than 10 mm. Stage architectural parameters are designed to achieve the maximum natural frequency and then further improved to ensure a robust motion along the working axis. A voice coil motor and a laser displacement sensor are adopted for actuation and sensing of the fabricated stage, respectively. Both finite-element analysis and experimental tests confirm a motion range over 11 mm. To facilitate a rapid and precise positioning in front of nonlinear effects, a discrete-time sliding mode control (DSMC) algorithm based on a proportional–integral-derivative (PID) type of sliding function is devised. The DSMC guarantees the stability of the system in the presence of model uncertainties and disturbances. The effectiveness of the presented DSMC is verified through experimental studies. Results show that the DSMC is superior to PID algorithm in terms of both transient response speed and steady-state accuracy.