Actuator device and method for limiting thermal drift

An actuator device, comprising:

• an actuator member comprising an electroactive polymer deformable in response to electrical stimulation,
• a temperature sensing means in thermal communication with the actuator member and adapted to obtain a measure of a temperature at the actuator member;
• and
• a controller operatively coupled to the temperature sensing means and arranged to supply to the actuator member, an electrical stimulus comprising an actuation signal for deforming the actuator member, and an AC heating signal superposed with the actuation signal for inducing heating of the electroactive polymer,
• wherein the controller is adapted to define a set temperature level for the actuator member, the set temperature level being a temperature elevated relative to an initial non-heated temperature of the actuator member, and
• wherein the controller is adapted to monitor an output of the temperature sensing means and adjust one or more of an amplitude and frequency of the AC heating signal in dependence upon the output so as to adjust the heating to maintain the temperature of the actuator member at a set level, the set level being a level elevated relative to the initial non-heated temperature of the actuator member.