Simultaneous Actuation and Force Estimation Using Piezoelectric Actuators

This paper introduces a force estimation method that enables simultaneous actuation and force estimation using piezoelectric actuators. The method combines an actuator input voltage and a current together with a displacement measurement to a force estimator. The force estimator contains a nonlinear actuator model to approximate the present external force without the use of force sensors. The measured displacement can simultaneously be utilized in feedback control to enable precise microrobotic operations. The results show that the method enables estimation of both static and varying forces under simultaneous position feedback control. Experimented displacement trajectories contain both stationary and mobile phases. The achieved accuracy in force estimation according to experiments is better than 10% of the full force scale. Therefore force sensing without the use of separate force sensors is feasible, which opens new applications for force sensing in microrobotics.