Electrorheological Shock Absorber Research Articles

Research of the influence of dissipative heating on the performance characteristics of electrorheological shock absorbers

The results of measurements (the dependences of temperature of the central part of the external surface on time; the dependences of the resistance force on the amplitude and frequency of motion of the rod of a electrorheological shock absorber) have shown that pressure drop in the annular channel and damper force of electrorheological shock absorbers are reduced on dissipative heating of an electrorheological fluid. A comparison of the performance characteristics of the developed shock absorber and a hydraulic passive shock absorber, and also with controlled shock absorbers of similar design but from two manufacturers of other countries, is carried out.

Design and Implementation of a High-Voltage Generator with Output Voltage Control for Vehicle ER Shock-Absorber Applications

A self-oscillating high-voltage generator is proposed to supply voltage for a suspension system in order to control the damping force of an electrorheological (ER) fluid shock absorber. By controlling the output voltage level of the generator, the damping force in the ER fluid shock absorber can be adjusted immediately. The shock absorber is part of the suspension system. The high-voltage generator drives a power transistor based on self-excited oscillation, which converts dc to ac. A high-frequency transformer with high turns ratio is used to increase the voltage. In addition, the system uses the car battery as dc power supply. By regulating the duty cycle of the main switch in the buck converter, the output voltage of the buck converter can be linearly adjusted so as to obtain a specific high voltage for ER. The driving system is self-excited; that is, no additional external driving circuit is required. Thus, it reduces cost and simplifies system structure. A prototype version of the actual product is studied to measure and evaluate the key waveforms. The feasibility of the proposed system is verified based on experimental results.

전자제어 현가장치를 위한 전기유변유체 쇽 업소버의 설계 및 성능평가

This paper presents design and performance evaluation of electro-rheological(ER) shock absorber for electronic control suspension(ECS). In order to achieve this goal, a cylindrical ER shock absorber that satisfies design specifications for a mid-sized commercial passenger vehicle is designed and manufactured to construct ER suspension system for ECS. After experimentally evaluating dynamic characteristics of the manufactured ER shock absorber, the quarter-vehicle ER suspension system consisting of sprung mass, spring, tire and the ER shock absorber is constructed in order to investigate the ride comfort and driving stability. After deriving the equations of the motion for the proposed quarter-vehicle ER suspension system, the skyhook controller is implemented for the realization of quarter-vehicle ER suspension system. In order to present control performance of ER shock absorber for ECS, ride comfort and driving stability characteristics such as vertical acceleration and tire deflection are experimentally evaluated under various road conditions and presented in both time and frequency domain.

Damping force characteristics of electrorheological shock absorbers with different electrode designs

This article presents the effect of electrode design parameters on the damping force of an electrorheological (ER) shock absorber for passenger vehicles. As a first step, an ER fluid is synthesized by dispersing arabic gum particles into non-conducting oil, and its field-dependent Bingham characteristics are experimentally evaluated. The Bingham model of the ER fluid is then formulated and incorporated with the governing equations of motion of the ER shock absorber. Subsequently, several ER shock absorbers are designed and manufactured with various electrode designs, which have three different electrode gaps, lengths, and materials, respectively. The field-dependent damping force of the manufactured shock absorbers is demonstrated in the time domain and compared with simulation results. In addition, the vibration control performance of a quarter-car suspension system is presented and compared with different electrode gaps and lengths.

Vibration control of an electrorheological fluid-based suspension system with an energy regenerative mechanism

This work presents vibration control of a vehicle suspension system using a controllable electrorheological (ER) shock absorber activated by an energy generator without external power sources. The ER shock absorber has a rack and pinion mechanism which converts a linear motion of the piston to a rotary motion. This rotary motion is amplified by gears and subsequently activates a generator to produce electrical energy. The generated voltage is experimentally evaluated with respect to excitation magnitude and frequency of the ER shock absorber. After evaluating the damping force using the regenerated voltage, a quarter-car ER suspension model is established. A skyhook controller is then formulated and experimentally implemented to attenuate vibration using the regenerated energy. It has been demonstrated via experiment that suspension vibration under bumpy and sinusoidal road conditions is significantly controlled by activating the ER shock absorber operated by the proposed regenerative energy mechanism.

Road test evaluation of vibration control performance of vehicle suspension featuring electrorheological shock absorbers

This work presents road test results for vibration control of a vehicle suspension system equipped with continuously controllable electrorheological (ER) shock absorbers. The test vehicle is a mid-sized passenger car whose suspension systems are typical Macpherson strut types for the front part and multilink types for the rear part. The four ER shock absorbers (two for the front suspension and two for the rear suspension) are devised based on design specifications for the test vehicle and their damping forces are experimentally evaluated with respect to the electric field. The ER shock absorbers and conventional spring elements are then assembled into suspension systems. Prior to undertaking the road test, the front ER suspension is applied to the quarter-car facility in order to validate control performance of the skyhook controller embedded in on-chip hardware. Subsequently, the full-vehicle model incorporating four ER suspensions is established and the skyhook control gains are determined in an optimal manner. The controller is then implemented on the test vehicle which is equipped with several sensors, a data acquisition system, and high-voltage amplifiers. Control performances are evaluated under various road conditions (bump, long waved, rugged, paved, and unpaved) and presented in both time and frequency domains.

Field Test on Vibration Control of Vehicle Suspension System Featuring ER Shock Absorbers

This study presents vibration control responses of a passenger vehicle equipped with continuously controllable electrorheological (ER) shock absorbers. As a first step, four ER shock absorbers (two for front parts and two for rear parts) are designed and manufactured based on the damping force levels and mechanical dimensions required for the middle-sized passenger vehicle. After experimentally evaluating the field-dependent damping force property and controllability, the manufactured ER shock absorbers are incorporated with the suspension of a car to be tested. Subsequently, the skyhook control algorithm, which is simple, but very effective in real field, is formulated by considering vertical, pitch, and roll motions. The controller is then realized by integrating feedback sensors, such as accelerometer and the field test is undertaken under bump and random road conditions. The control responses for the ride quality and steering stability are evaluated in both time and frequency domains. In addition, the performance comparison between conventional suspension and ER suspension is carried out.

Model of an electro-rheological shock absorber and coupled problem for partial and ordinary differential equations with variable unknown domain

Amortization of a shock in an electro-rheological shock absorber is carried out in the motion of a piston in an electrorheological fluid. The drag force acting on the piston is regulated by varying the voltage applied to electrodes. A model of an electrorheological shock absorber is constructed. A problem on shock absorber reduces to the solution of a coupled problem for motion equation of the piston and non-linear equations of fluid flow in an unknown domain that varies with the time. A method of semi-discretization for approximate solution of the coupled problem is considered. Results on the existence and on the uniqueness of the solution of the coupled problem are obtained. Convergence of approximate solutions to the exact solution is proved. Numerical simulation of the operation of the shock absorber is performed.

Use of electro-rheological fluids in a damping device

This paper presents results of experimental studies of an electro-rheological shock absorber based on a controlled hydrosuspension designed to damp a wheeled tractor driver’s cab accommodating not only the operator but also complex electronic equipment by regulating the rheological characteristics of the working fluid by means of an external electric field. The characteristics and dependences of the operating conditions of the electro-rheological shock absorber are presented. The dissipative processes have been estimated.

DESIGN PROGRAM IN GRAPHIC USER INTERFACE ENVIRONMENT FOR AUTOMOBILE ER DEVICES

This work presents a design and analysis program for vehicle devices utilizing an electrorheological (ER) fluid. The program is operated in graphic user interface (GUI) environment and the initial window is consisted of four subprogram modules which are related to ER shock absorber, ER seat damper, ER engine mount, and ER anti-lock brake system (ABS), respectively. In order to execute each module, both material properties and design parameters are to be chosen by the user. Then, the output display window shows the field-dependent performance characteristics to be considered as design criteria. In addition, control performances of the vehicle system equipped with ER devices are displayed in time and frequency domain. In order to demonstrate the effectiveness of the proposed program, ER shock absorber and ER ABS are designed and manufactured and their performance characteristics are evaluated.

Design and analysis programme of electrorheological devices for vehicle systems

In this work, a dynamic program for design and analysis of electrorheological (ER) devices for vehicle systems is developed in a graphic user-interface (GUI) environment. The initial window of the program shows four subprogram modules which are related to the design of ER shock absorber, ER seat damper, ER engine mount and ER anti-lock brake system, respectively. Each module consists of three structures: input design parameter, dynamic analysis, and output display. In order to demonstrate the effectiveness of the proposed program, the ER shock absorber and ER engine mount are designed and manufactured on the basis of the program. A comparison of damping force characteristics between analysed and measured results is undertaken.

Performance comparison of vehicle suspensions featuring two different electrorheological shock absorbers

This paper proposes a novel type of semi-active electrorheological (ER) shock absorber for a small-sized passenger vehicle. The field-dependent damping forces of the proposed orifice type of ER shock absorber are experimentally evaluated and compared with those of a conventional cylinder type of ER shock absorber. The governing equations of motion for a vehicle suspension system equipped with ER shock absorbers are derived and an optimal controller is designed to attenuate vibration due to bump and random road excitations. Control responses such as vertical acceleration of the vehicle body are evaluated in time and frequency domains, and comparative work is done between the orifice type and cylinder type of ER shock absorbers.

Double adjustable shock absorbers utilising electrorheological and magnetorheological fluids

Double adjustable shock absorbers allow for independent adjustment of the yield force and post-yield damping in the force versus velocity response. To emulate the performance of a conventional double adjustable shock absorber, an electrorheological (ER) and magnetorheological (MR) automotive shock absorber were designed and fabricated at the University of Maryland. For the ER shock absorber, an applied electric field between two tubular electrodes, located in the piston head, increases the force required for a given piston rod velocity. For the MR shock absorber, an applied magnetic field between the core and flux return increases the force required for a given piston rod velocity. For each shock absorber, two different shaped gaps meet the controllable performance requirements of a double adjustable shock absorber. A uniform gap allows for control of the yield force of the shock absorber, while a nonuniform gap allows for control of the post-yield damping. Force measurements from sinusoidal displacement cycles, recorded on a mechanical damper dynamometer, validate the performance of uniform and non-uniform gaps for adjustment of the yield force and post-yield damping, respectively.

Field test results of a semi-active ER suspension system associated with skyhook controller

Performance characteristics of a semi-active ER (electro-rheological) suspension system are evaluated through the field test of a passenger car. Four ER shock absorbers are designed and manufactured for both front and rear parts, and their field-dependent damping properties are investigated. Subsequently, four independent skyhook controllers associated with ER shock absorbers are formulated by considering the vertical motions of the body and wheel of the car to be tested. Both ride comfort and steering stability of the car are evaluated via the field test showing bump and squat test responses.

Control Characteristics of ER Devices

The successful development of a new generation of technology incorporating an electro-rheological (ER) fluid requires three principal ingredients; advanced ER fluid, reliable mechanical mechanism and efficacious control scheme. This paper discusses the third one. After describing general, but stringent requirements for semiactive or active control systems featuring the ER fluid, feedback control characteristics of some specific ER devices are presented; a frequency-dependent feedback control of mode shape in a smart flexible structure containing the ER fluid, an optimal control of vibration in a semi-active suspension installed with ER shock absorbers, and a neural network control of position in a hydraulic ER valve-cylinder system.

Optimum Design of Hydraulic Shock Absorber Using Electrorheological Fluid.

We propose an optimum design method for a new of type hydraulic shock absorber in which the resisting force matches that of impacts of various masses using electrorheological (ER) fluid having apparent viscosity that can be modified with an electric field. Comparing the results of the optimally designed ER shock absorber and an existing shock absorber with a metering pin, it is shown that the maximum acceleration of a light body (1250kg) nearly equals that of a heavy body (2250kg) during impact for a system containing the ER shock absorber, while the maximum acceleration of the former is about 2 times that of the latter during impact for a system containing the existing shock absorber. In addition, it is shown that the maximum accelerations obtained using the optimum design method are reduced by 0.9∼8.9% compared with those obtained using a method proposed in a previous paper using a constant resisting force in the shock absorber.

Hydraulic Shock Absorber Using Electrorhelolgical Fluid. Two-Mass System with High-Capacity Absorber.

We propose a high-capacity hydraulic shock absorber using electrorheological (ER) fluid having apparent viscosity that can be modified by an electric field. In this report, we determine area of an orifice of the ER shock absorber during impact of a light body (1 250 kg), and characteristics of resisting force of the absorber due to the ER effect during impact of a heavy body (2 250 kg) by extending a method proposed in a previous paper using a constant resisting force of the absorber. Furthermore, we show by simulation that the maximum accelaration of the light body nearly equals that (about 1g) of the heavy body during impact for a two-mass system containing the ER shock absorber, while the maximum acceleration of the former is about 2 times that (about 1g) of the latter during impact for a two-mass system containing an existing shock absorber with a metering pin.