Dynamic Modeling Of Cone Dielectric Elastomer Actuator And Vibration Control With Shaping Technology

Dielectric elastomer actuators have shown great research and application potential in soft robots,precision optics,transducers,vibration dampers and other fields,due to the high deformation ability,fast response ability and self-sensing performance.However,the inherent vibration characteristics and non-linearity of the dielectric elastomer actuator result in responses containing multiple harmonic components,which affects the positioning accuracy and operating quality of the system.Meanwhile,it is easy to excite mechanical resonance and limit the vibration suppression performance.This dissertation presents vibration control methods based on shaping technology for cone dielectric elastomer actuators.Methods aim to eliminate natural vibration and external interference,expanding the application in the fields of motion control and active vibration isolation.The main research contents are as follows:Based on the mechanical structure,electric driving principle and viscoelastic characteristics of materials,the physical model of cone dielectric elastomer actuators was established.In order to realize the parameter identification and system control,the physical model is characterized as a dynamic model composed of a quadratic nonlinear term and a third-order linear system through approximate linearization.Static parameters and transient parameters of actuators are identified in two steps by establishing the maximum error and fitness values.The ratio of the maximum error to the maximum displacement in the static identification is 2.24%,while fitness values in the transient identification is 86.05%.The result verifies the effectiveness of the dynamic model in characterizing the coupling system.The nonlinear characteristics of the system and model are confirmed through time-frequency analysis,and the effects of parameters such as input voltage,loads and pre-stretch rate on the static characteristics and natural frequency are also discussed.An extra-insensitive shaper with distributed delays and closed-loop inverse shaper based on this shaping principle are proposed.Traditional input shapers are designed for linear system and limited by the model accuracy.The proposed shaper of the delay shaper improves the robustness against to the unmodeled system modal and modeling errors by changing the configuration method of zero points.The transfer function and the parameter estimation method of the shaper are addressed.The vibration attenuation of the cone dielectric elastomer actuator with the proposed shaper is 95.6%,which is nearly 1.5 times the average of other shapers.The adjustment time is shortened by 52.5% compared with the uncontrolled one.In order to improve the anti-interference ability of the shaping controller,the extra-insensitive inverse shaper with distributed delays is designed.The local feedback control can attenuate 80.7% of natural vibration and 66% of interference vibration,which is nearly 2 times the average of other shapers.The main feedback control can attenuate nearly 50% of vibration and interference,resulting the system stability quickly.Active vibration isolation system with cone dielectric elastomer actuators is designed and manufactured,as well as the dynamic model.The influence of parameters such as input voltage,loads and pre-stretch rate on the passive vibration isolation and semi-active vibration isolation of the system is discussed by solving the vibration transmission rate under the basic disturbance.The resonance peak of active vibration isolation system is reduced effectively based on the passive vibration isolation when the extra-insensitive inverse shaper with distributed delays is introduced to the system.The control method is proposed including the square root nonlinear compensator,the PID feedback controller and the inverse shaper.The vibration isolation performance of system with such a control method is verified under the single-frequency harmonic disturbance and frequency-swept disturbance.The results show that the active vibration isolation system suppresses more than90% of single-frequency harmonic vibration(5Hz,15 Hz,20Hz)compared with the performance of passive vibration isolation and can effectively isolate narrow-band sweep frequency vibration within 5-30 Hz.