Characterisation, modelling and hysteresis compensation in a tubular dielectric elasomer actuator

Of the range of dielectric elastomer-based actuators that have been developed rolled tubular actuators are among the most promising. These provide larger forces by making multiple layers of dielectric elastomer apply their actuation forces in parallel. Rolled tubular actuators closely mimic muscle functionality providing axial elongation on application of a voltage. The operating characteristics of the tubular actuator that limit position control performance are (a) nonlinear steady-state voltage-strain behaviour, (b) asymmetric hysteresis behaviour, and (c) reversible creep. This contribution initially reviews these characteristics and then examines simple open-loop control with inverse hysteresis model-based compensation when the reference signals are periodic. Polynomial models are used to describe the rising and descending characteristics of the asymmetric hysteretic behaviour. This simple modelling approach provides a computationally fast solution for real-time control purposes.