Shuai Wu

The Nonlinear Accuracy Model of Electro-Hydrostatic Actuator

The electro-hydrostatic actuator (EHA) is a kind of power-by-wire (PBW) actuator. In this paper, a typical architecture of EHA is described and the block diagram model of EHA is established directly from the mathematic equations without transfer functions, which is a nonlinear accuracy model. The influence of refeeding circuit on the EHA system is discussed based on the comparison with conventional linear model. A gain-variable PID controller is introduced to this model to compensate the friction.

Design and numerical simulation of a continuable and bidirectional piezo-hydraulic servo pump

Hydraulic servo pump is extremely important to achieve high dynamic performance and large power density of distributed actuation systems in modern aircrafts. In this study, a piezo-hydraulic servo pump (PHSP) with multiple piezoelectric stacks (PZT stacks) is proposed. The key feature of this design is the development of a mutual active valve rectification method. Based on the novel rectification technology, the PZT stacks operate in phases to acquire a continuable oil supply of PHSP, which is unreachable in conventional single PZT stack driven pump. Moreover, the flow rate and flow direction of this pump can be adjusted as demanded rapidly and conveniently. The mutual active valve rectification method is also available when more PZT stacks are incorporated into the pump to achieve larger power output. This paper presents the design concept and working principle of PHSP. A dynamic model is formulated analytically to validate the system principle. The simulation results are acquired to evaluate the pump performance. A research prototype is developed for experimental purpose and control implementation.

High accuracy position adjustment and vibration isolation actuator with the controlled ferrofluid

An actuator for microposition adjustment and vibration isolation using the controlled ferrofluid is reported in this letter. The proposed actuator levitates on the ferrofluid which is affected by the combined dynamic magnetic field which is formed by coupling a permanent magnetic field with a controlled electromagnetic field. A controlled electromagnetic field is superposed on the permanent magnetic field in order to change the shape of the ferrofluid to ultimately move the actuator. The experimental results indicate that the proposed actuator can adjust the position with high accuracy and has a good dynamic performance. The proposed actuator can bear over 2 N loads, and the positioning accuracy is within 0.1 μm. The stroke of the actuator is about of ±30 μm with no load, and the stroke increases to ±75 μm at 2 N load. Its dynamic band with –3 dB amplitude attenuation and –90° phase is over 40 Hz. In addition, the displacement has a very good linear relationship with the input current. The results also de...

A new rotary voice coil motor suitable for short angular strokes-design, modeling and optimization

This paper describes a new design of a rotary voice coil motor (RVCM) which suitable for short angular stroke. Reluctance model of proposed RVCM is discussed. Aimed at the requirement of rotary direct drive valve, an optimization objective function which takes into account the maximum acceleration ability and the magnet circuit is formulated. The design parameters optimization is carried out by the particle swarm optimization(PSO) method. The optimized parameters are validated by the FEM method. It is shown that the new design enhances the maximum acceleration ability which means high frequency response.

Design and analysis of a Limited angle torque motor with Dual Halbach Arrays

This paper present a new design of a Limited angle torque motor (LATM) with Dual Halbach Arrays for rotary direct drive valve (DDV), which needs high frequency response, high power to weight ratio. Reluctance model of proposed LATM is discussed. The structure parameters are optimized by particle swarm optimization (PSO) method to improve performances, especially the output torque. The optimized parameters are validated by the FEM method. It is shown that the new design improves the output torque significantly.

A High Flow Rate and Fast Response Electrohydraulic Servo Valve Based on a New Spiral Groove Hydraulic Pilot Stage

High flow rate electrohydraulic servo valve is widely applied in hydraulic servo systems. Typical high flow rate servo valve is three-stage nozzle flapper pilot structure which is complicated, unreliable, and highly costly. This study proposed a new two-stage structure high flow rate and quick response electrohydraulic spiral pilot servo valve (ESPV) using a novel hydraulic full bridge spiral pilot stage (FBSPS) as hydraulic amplifier. Its structure is simpler than traditional servo valve which could increase reliability. A design parameters optimization method for servo valve is proposed. It is using an optimization objective function which can balance dynamic performance, static performance, and pilot state efficiency for different design objectives. The particle swarm optimization (PSO) method was applied to get the best key design parameters of ESPV. A research prototype was developed based on the optimized parameters for fast response. The experimental results indicated that the frequency bandwidth (−3 dB amplitude attenuation and −90 deg phase lag) of the ESPV is up to 150 Hz at 20% of full range. This frequency response performance is competitive with existing servo valves, and the simpler structure can improve reliability and reduce cost. Thus, it may have great potential in hydraulic servo system with high reliability requirement, such as aircraft hydraulic servo control system.

Design and simulation of Voice Coil Motor for the micro-electric load simulator

The advance of high-frequency response and micro-torque electric actuator motivates the study on high performance motor for load simulator. A novel high-precision swing-arm Voice Coil Motor (VCM) has been proposed in this paper. The research investigates the feasibility of this new structure applied to the VCM. Abiding by the equivalent rotary inertia idea, mechanical structure and magnetic field interactive design have been implemented with the electromagnetic simulation software-Ansofts Maxwell. An iterative optimal design process is then proposed to maximize the force constant of the VCM and to minimize the inertia of the rotor. Simulation results are given to illustrate that the proposed design procedure can preliminarily achieve a satisfactory performance.

Feasibility Study on the Use of a Voice Coil Motor Direct Drive Flow Rate Control Valve

This paper considers the feasibility of a new type of voice coil motor direct drive flow control servo valve. The proposed servo valve controls the flow rate using only a direct measurement of the spool position. A neural network is used to estimate the flow rate based on the spool position, velocity and coil current. The estimated flow rate is fed back to a closed loop controller. The feasibility of the concept is established using simulation techniques only at this point. All results are validated by computer co-simulation using AMESim and Simulink. A simulated model of a VCM-DDV (Voice Coil Motor-Direct Drive Valve) and hydraulic test circuit are built in an AMESim environment. A virtual digital controller is developed in a Simulink environment in which the feedback signals are received from the AMESim model; the controller outputs are sent to the VCM-DDV model in AMESim (by interfacing between these two simulation packages). A LQR (Linear Quadratic Regulator) state feedback and nonlinear compensator controller for spool position tracking is considered as this is the first step for flow control. A flow rate control loop is subsequently included via a neural network flow rate estimator. Simulation results show that this method could control the flow rate to an acceptable degree of precision, but only at low frequencies. This kind of valve can find usage in open loop hydraulic velocity control in many industrial applications.Copyright

Preliminary design and multi-objective optimization of electro-hydrostatic actuator

Electro-hydrostatic actuator is generally regarded as the preferred solution for more electrical aircraft actuation systems. It is of importance to optimize the weight, efficiency and other key design parameters, during the preliminary design phase. This paper describes a multi-objective optimization preliminary design method of the electro-hydrostatic actuator with the objectives of optimizing the weight and efficiency. Models are developed to predict the weight and efficiency of the electro-hydrostatic actuator from the requirements of the control surface. The models of weight prediction are achieved by using scaling laws with collected data, and the efficiency is calculated by the static energy loss model. The multi-objective optimization approach is used to find the Pareto-front of objectives and relevant design parameters. The proposed approach is able to explore the influence of the level length of linkage, displacement of pump and torque constant of motor on the weight and efficiency of the electro-hydrostatic actuator, find the Pareto-front designs in the defined parameter space and satisfy all relevant constraints. Using an electro-hydrostatic actuator for control surface as a test case, the proposed methodology is demonstrated by comparing three different conditions. It is also envisaged that the proposed prediction models and multi-objective optimization preliminary design method can be applied to other components and systems.

Energy reverse transmission analysis of collaborative rectification structure pump

This paper studies the energy reverse transmission of a new type collaborative rectification structure pump, which uses a linear reciprocal machine drives a piston directly to pump hydraulic fluid. This pump is designed for a novel electro-hydrostatic actuator which is a kind of volume control electro-hydraulic servo system. For servo control application, the pump is usually required to transfer energy in both positive and reverse direction, which means it not only can work as a pump, but also be required to work as a motor to drive the electrical machine as a generator. The purpose of this research is to study the characteristics of reverse transmission of this new pump. The kinematics flow rate model and dynamic model of the pump are presented firstly, and then a proof of the ability of reverse transmission and the stability criterion are discussed. Finally its characteristics in reverse transmission are verified based on simulation.