The nonlinear pull-in behaviors of various electrostatic micro-actuators were simulated. The differential quadrature method (DQM) was applied to overcome the difficulty in solving the nonlinear equation of motion. Various types of micro-actuators, such as the cantilever beam actuator and the fixed-fixed beam actuator were derived and simulated to examine the feasibility of applying the DQM to t...

Highly maneuverable aircraft has redundant electrohydraulic actuators that generate the forces to drive the aircraft control surfaces. Two problems are important in these actuators. First, during reconfiguration of the actuator channels the hydraulic system works in the full range of its parameters. It leads to strongly nonlinear models of the redundant servo. Second, the frequency bandwidth of...

Since the actuator capacity is limited, in the real application of active control systems under sever earthquakes it is conceivable that the actuators saturate, hence the actuator saturation should be considered as a constraint in design of optimal controllers. In this paper optimal design of active controllers for nonlinear structures by considering actuator saturation, has been studied. The p...

The rehabilitation exoskeleton is an effective piece of equipment for stroke patients and the aged. However, this complex human–robot system incurs many problems, such as modeling uncertainties, unknown interaction, external disturbance, actuator fault. This paper addresses adaptive fault-tolerant tracking control a lower limb joint driven by electro-hydraulic (EHA). First, model built consider...

This study presents application of Dynamic Programming towards finding globally optimal control policies of a new, highly-efficient hydraulic elevator architecture. The architecture employs an actuator, three accumulators, and two hydraulic circuits bridged by a hydraulic transformer. An auxiliary electric motor exists only to compensate for system losses. Prior research identified a multitude ...

This paper describes the development of linear parameter varying (LPV) models and an LPV-H∞ controller for one degree of freedom (DoF) electro-hydraulic systems. A virtual set-up consists of a hydraulic actuator driven by a servovalve and supplied from a constant-pressure power unit. The LPV models are derived based on two techniques: black-box modeling and the analytical description of the sys...

The hydrostatic actuation system based on linear actuators improves the complex piston force and long transmission path of traditional electro-hydrostatic actuator (EHA). However, new nonlinear factors in direct-driven are introduced into system, which present challenges to modeling control. To improve accuracy performance prediction, this paper analyzed working characteristics an electromagnet...