Self-sensing Electro-ribbon Actuators

In this paper, we investigate the viability of capacitance self-sensing of electro-ribbon actuators, allowing them to be used simultaneously as an actuator and a sensor. Initially the electro-ribbon actuator was implemented only as a sensor, and it was found that the exponential relationship between capacitance and displacement made the device a poor sensor at distances greater than 2 mm. When used simultaneously as an actuator and a sensor, the ‘zipping’ motion of the electrodes changed this relationship, making it more suitable for position sensing. Capacitance was found to be a good indicator of the amount of zipping experienced by the electrodes. For effective displacement sensing, the mass of the the load being applied to the actuator should be known. Finally, a closed-loop PI position control system using self-sensing feedback was implemented. The results demonstrated that, provided the applied load is known, capacitive self-sensing can be used to control the position of electro-ribbon actuators with reasonable accuracy.