Novel electro-hydraulic position control system for primary mirror supporting system

Abstract

In the field of modern large-scale telescope, primary mirror supporting system technology faces the difficulties of theoretically uniform output force request and bias compensation. Therefore, a novel position control system combining hydraulic system with servo motor system is introduced. The novel system ensures uniform output force on supporting points without complicating the mechanical structure. The structures of both primary mirror supporting system and novel position system are described. Then, the mathematical model of novel position control system is derived for controller selection. A proportional-derivative controller is adopted for simulations and experiments of step response and triangle path tracking. The results show that proportional-derivative controller guarantees the system with micrometerlevel positioning ability. A modified proportional-derivative controller is utilized to promote system behavior with faster response overshoot. The novel position control system is then applied on primary mirror supporting system. Coupling effect is observed among actuator partitions, and relocation of virtual pivot supporting point is chosen as the decoupling measurement. The position keeping ability of the primary mirror supporting system is verified by rotating the mirror cell at a considerably high rate. The experiment results show that the decoupled system performs better with smaller bias and shorter recovery time.

A novel miniature hydraulic actuation system and offset to long hose effect

“…A proportionalderivative (PD) controller was used in the system and verified to have micrometer-level positioning ability. 8 Taking nonlinearities of friction and internal leakage into consideration, another method of position control strategy of an electrohydraulic actuation system was implemented by employing a fuzzy logic controller (FLC) whose parameters were optimized using particle swarm optimization (PSO). 9 A velocity feedback was added in a position control model to improve the bandwidth of a servo-hydraulic linear actuator.…”

Admittance control of an electro-hydraulic servo-drive

“…We have been dealing with these problems for decades. At this time, a number of mutually different methods and algorithms were created (Peng et al, 2016;Shaer et al, 2017). Each of the proposed methods contains a few advantages and disadvantages, and cannot be used to implement all tasks (Rahmat et al, 2010;Yuan et al, 2017).…”