A field-driven electroactive polymer actuator is provided with a current sensor for sensing a current flowing to the actuator. A control circuit is used for driving the actuator which includes a voltage source. The driving of the actuator is controlled in dependence on the sensed current, thereby to provide a predetermined charge delivery for particular changes in actuation level of the actuator.This provides a combined voltage-based and current-based drive scheme for a voltage-driven EAP actuator, and it enables mechanical movements of the actuator to be more reliably repeated.