A Semi-Active Damper Design for Use in a Terrain Adaptive Ankle Prosthesis

2011 ◽  
Author(s):  
Andrew LaPre` ◽  
Frank Sup
Keyword(s):  
Control Valve ◽  
Servo Control ◽  
Heel Strike ◽  
Hydraulic Actuator ◽  
Dynamic Damping ◽  
Human Ankle ◽  
Performance Specifications ◽  
Damper Design ◽  
Active Damper ◽  
The Mathematical Model

State-of-the-art commercial ankle prostheses enable amputees to walk on level ground replicating the passive biomechanics of able-bodied persons reasonably well. However, when navigating uneven terrains (such as slopes and stairs) these devices do not allow the ankle to adjust to the ground at each step in order to maintain stable contact. At these instances, the probability of falling is greatly increased. In contrast, the natural ankle adapts passively (i.e. no net positive power is required) just after heel strike allowing the foot to conform to the ground. This paper focuses on developing a continuously variable damper that can be paired with a carbon fiber foot in order to replicate the passive adaption dynamics of the human ankle. Presented in this paper are the performance specifications, the mathematical model, and the resulting device design for the semi-active damping system. The design consists of a hydraulic actuator, coupled to a servo control valve which modulates the damping. The system is designed to replicate the dynamic damping range of an able-bodied ankle joint by achieving flow rates as high as 2.0 liters per minute at 1.0 MPa, and operate at up to 20 MPa.

scholarly journals DIESEL INJECTOR PUMP WITH RING CONTROL VALVE

2020 ◽  
pp. 68-76
Author(s):  
Fanil' Gabdrafikov ◽  
Irshat Aysuvakov ◽  
Ilgiz Galiev
Keyword(s):  
Fuel Injection ◽  
Ring Width ◽  
Control Valve ◽  
Free Edge ◽  
Original Position ◽  
Design Parameters ◽  
Elastic Ring ◽  
Hydraulic Actuator ◽  
Wide Range ◽  
Ring Valve

The studies were carried out with the aim of modernizing the pump injector with a hydraulic actuator of the HEUI system plunger with the development of a control valve model based on a split elastic ring that provides fast fuel injection control. The upgraded device differs from the existing ones in that instead of a control freely floating valve (ball) or a poppet valve with springs, a valve in the form of a split elastic ring is installed in the valve assembly. One end of this ring is fixed rigidly, the other is freely movable to block the drain channel of the liquid. The canal overlaps the free edge of the ring when the electromagnet is turned on (installed with a gap inside the ring), and also (in the absence or malfunction of the electromagnet) from the valve itself running under the pressure of the supplied fluid. When upgrading the pump injector by the proposed method and using an annular control valve with electronic control (with optimal ring parameters), a new technical effect is achieved - reducing the response time of the control valve. This is due to the fact that the free edge of the split elastic ring, like a mechanical multiplier, blocks the drain canal π times faster than the valve stroke when it rises from the pressure of the fluid flow or signal when the electromagnet is on. The ring valve simultaneously acts as a spring to return to its original position, simplifying the design as much as possible. In the course of research, a new mathematical expression was derived for calculating the valve stroke depending on its design parameters. Using this formula, the optimal parameters of the control ring valve of the pump injector were established, which affect the quality of fuel injection in a wide range of diesel operation: diameter - 20 mm, ring width - 12 mm, thickness - 0.46 mm, diameter of the control fluid supply canal - 3 mm.

scholarly journals Pneumatic Actuator Controlled by Proportional Valve. Experimental results

2021 ◽  
Vol 286 ◽  
pp. 04010
Author(s):  
Valentin Nicolae Cococi ◽  
Constantin Călinoiu ◽  
Carmen-Anca Safta
Keyword(s):  
Control Valve ◽  
Industrial Applications ◽  
Experimental Results ◽  
Pneumatic Actuator ◽  
Proportional Valve ◽  
Controlled Systems ◽  
Automation Systems ◽  
Simulation Results ◽  
The Mathematical Model ◽  
Fire Ignition

In nowadays the pneumatic controlled systems are widely used in industrial applications where valves must be operated, where there is a fire ignition risk, or in different automation systems where a positioning action is desired. The paper presents the experimental results of a pneumatic actuator controlled by a proportional control valve. The goal of the paper is to compare the experimental results with the numerical simulation results and to improve the mathematical model associated with the experiment.

scholarly journals On Numerical Simulation Approach for Multiple Resonance Modes in Servo Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Qixin Zhu ◽  
Hongli Liu ◽  
Yiyi Yin ◽  
Lei Xiong ◽  
Yonghong Zhu
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Closed Loop ◽  
Resonance Mode ◽  
Servo Control ◽  
Simulation Approach ◽  
Servo Systems ◽  
Resonance Modes ◽  
Resonant Part ◽  
The Mathematical Model

Mechanical resonance is one of the most pervasive problems in servo control. Closed-loop simulations are requisite when the servo control system with high accuracy is designed. The mathematical model of resonance mode must be considered when the closed-loop simulations of servo systems are done. There will be a big difference between the simulation results and the real actualities of servo systems when the resonance mode is not considered in simulations. Firstly, the mathematical model of resonance mode is introduced in this paper. This model can be perceived as a product of a differentiation element and an oscillating element. Secondly, the second-order differentiation element is proposed to simulate the resonant part and the oscillating element is proposed to simulate the antiresonant part. Thirdly, the simulation approach for two resonance modes in servo systems is proposed. Similarly, this approach can be extended to the simulation of three or even more resonances in servo systems. Finally, two numerical simulation examples are given.

scholarly journals Estimation of the Two Degrees-of-Freedom Time-Varying Impedance of the Human Ankle

2018 ◽  
Vol 12 (1) ◽  
Author(s):  
Evandro Ficanha ◽  
Guilherme Ribeiro ◽  
Lauren Knop ◽  
Mo Rastgaar
Keyword(s):  
Degrees Of Freedom ◽  
Mechanical Impedance ◽  
Heel Strike ◽  
Time Varying ◽  
Two Degrees Of Freedom ◽  
Impedance Modulation ◽  
Ankle Stiffness ◽  
Human Ankle ◽  
Stiffness And Damping ◽  
And Inversion

An understanding of the time-varying mechanical impedance of the ankle during walking is fundamental in the design of active ankle-foot prostheses and lower extremity rehabilitation devices. This paper describes the estimation of the time-varying mechanical impedance of the human ankle in both dorsiflexion–plantarflexion (DP) and inversion–eversion (IE) during walking in a straight line. The impedance was estimated using a two degrees-of-freedom (DOF) vibrating platform and instrumented walkway. The perturbations were applied at eight different axes of rotation combining different amounts of DP and IE rotations of four male subjects. The observed stiffness and damping were low at heel strike, increased during the mid-stance, and decreases at push-off. At heel strike, it was observed that both the damping and stiffness were larger in IE than in DP. The maximum average ankle stiffness was 5.43 N·m/rad/kg at 31% of the stance length (SL) when combining plantarflexion and inversion and the minimum average was 1.14 N·m/rad/kg at 7% of the SL when combining dorsiflexion and eversion. The maximum average ankle damping was 0.080 Nms/rad/kg at 38% of the SL when combining plantarflexion and inversion, and the minimum average was 0.016 Nms/rad/kg at 7% of the SL when combining plantarflexion and eversion. From 23% to 93% of the SL, the largest ankle stiffness and damping occurred during the combination of plantarflexion and inversion or dorsiflexion and eversion. These rotations are the resulting motion of the ankle's subtalar joint, suggesting that the role of this joint and the muscles involved in the ankle rotation are significant in the impedance modulation in both DP and IE during gait.

Simulacija i odstranjivanje stick-slip efekta servosistema sprovodnog aparata hidraulične turbine

2021 ◽  
Vol 23 (1) ◽  
pp. 37-41
Author(s):  
Darko Babunski ◽  
◽  
Emil Zaev ◽  
Atanasko Tuneski ◽  
Laze Trajkovski ◽  
...  
Keyword(s):  
Hydraulic Cylinder ◽  
Friction Model ◽  
Slip Effect ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
Stick Slip ◽  
Hydro Turbine ◽  
Servo Mechanism ◽  
The Mathematical Model ◽  
Slip Phenomenon

Friction is a repeatable and undesirable problem in hydraulic systems where always has to be a tendency for its removal. In this paper, the friction model is presented through which the most accurate results are achieved and the way of friction compensation, approached trough technique presented with the mathematical model of a hydraulic cylinder of a hydro turbine wicket gate controlled by a servomechanism. Mathematical modelling of a servo mechanism and hydraulic actuator, and also the simulation of hydraulic cylinder as a part of a hydro turbine wicket gate hydraulic system where the stick-slip phenomenon is present between the system components that are in contact is presented. Applied results in this paper and the theory behind them precisely demonstrate under what circumstances the stick-slip phenomenon appears in such a system. The stick-slip effect is simulated using Simulink and Hopsan software and the analysis of the results are given in this paper. Removal of the stick-slip effect is presented with the design of a cascade control implemented to control the behaviour of the system and remove the appearance of a jerking motion.

Nonlinear behavior of muscle reflexes at the human ankle joint

1995 ◽  
Vol 73 (1) ◽  
pp. 65-72 ◽  
Author(s):  
R. B. Stein ◽  
R. E. Kearney
Keyword(s):  
Ankle Joint ◽  
Stretch Reflex ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Random Perturbations ◽  
Hydraulic Actuator ◽  
Voluntary Activity ◽  
Highly Nonlinear ◽  
Human Ankle

1. Pulse inputs (similar to tendon jerks) were applied to the human ankle joint with the use of a hydraulic actuator. Inputs of only 1-2 degrees could elicit large responses (> 20% of maximum voluntary contraction). The magnitude of the response depended nonlinearly on a number of factors: the amplitude, direction, and duration of the pulse; the angle of the ankle; and the level of voluntary activation of the ankle muscles. 2. Pulses that flexed or extended the ankle could both produce reflex torques in the same direction (extensor torque). Although an extension of the ankle did not itself produce a response, it could affect the response to a subsequent flexion for up to 1 s. 3. The influence of random perturbations on the stretch reflex at the ankle was assessed. Responses to pulse displacements alone and to pulses superimposed on random perturbations were compared at the same level of voluntary activity. Reflex responses decreased in a graded manner with increasing amplitude or bandwidth of the random perturbations. 4. These results demonstrate that stretch reflexes can generate substantial torques, but in a highly nonlinear manner. In particular, passive joint movements markedly alter stretch reflex gain, and these changes must be considered in interpreting the functional significance of reflex actions.

Electro Hydraulic Gas Exchange Valve Actuation of 4-Stroke Large Bore Diesel Engine

2014 ◽  
Author(s):  
Mika Herranen ◽  
Kalevi Huhtala
Keyword(s):  
Diesel Engine ◽  
Gas Exchange ◽  
Power Consumption ◽  
Controller Design ◽  
Control Valve ◽  
Hydraulic Actuator ◽  
Direction Control ◽  
Test Engine ◽  
Return Spring ◽  
Valve Actuation

After several years of study, a large bore diesel engine Electro-Hydraulic Valve Actuation (EHVA) system has reached a development point where the system has been successfully used for years in laboratory test engine environment too. During the evolution of the EHVA, insight of the hydraulic and control systems features has been cleared. This paper concludes main findings and results of EHVA research in Tampere University of Technology / IHA. The hydraulic circuit effect to the power consumption of EHVA is clear. 3-way controlled actuator has advantages compared to 4-way controlled system. Direction control valve defines controllability of the system, and has source of the largest single component power loss. Hydraulic actuator design has also a fair effect to the overall power consumption when pressure force vs. required flow changes heavily, due to load forces. Mechanically, return spring design of the gas exchange valve has great effect to power consumption too. Controller design is dependent on what kind of performance is required. The controller compensates lack of control valve bandwidth, and reacts to changing environmental variables. In this state, the Iterative Learning Controller (ILC) has proved the best choice. If gas exchange valve exact lift motion during the lift event is not important but variation between the strokes is kept in narrow range, a Model-Based Controller (MBC) is a strong option.

Laboratory Investigation of Seat Suspension Performance During Vibration Testing

2006 ◽  
Author(s):  
Alan G. Mayton ◽  
Joseph P. DuCarme ◽  
Christopher C. Jobes ◽  
Timothy J. Matty
Keyword(s):  
Occupational Safety ◽  
Head Injuries ◽  
Surface Mining ◽  
Mr Damper ◽  
Vertical Vibration ◽  
Vibration Exposure ◽  
Seat Suspension ◽  
Damper Design ◽  
Active Damper ◽  
Spring Mechanism

Mining injury statistics show that a significant number of back, neck, and head injuries are linked to exposure from vehicle vibration. Use of a suspension seat is a common way to isolate the vehicle operator from the adverse effects of vibration exposure. Thus, researchers at the National Institute for Occupational Safety and Health1 - Pittsburgh Research Laboratory (NIOSH - PRL) performed laboratory studies on four passive and two semi-active seat suspension designs. These are typical of seat suspensions commonly found on large off-road heavy surface mining, construction and agricultural vehicles as either replacement or original equipment manufacturer (OEM) systems. One included a pneumatic (air bladder) spring mechanism. The fifth and sixth suspensions were a NIOSH magnetorheological (MR) semi-active damper design based on the pneumatic (air bladder) and one of the coil spring suspensions above. These suspensions were modified with a commercially available MR damper substituted for the OEM damper. These six seat suspension systems were tested and analyzed, for vertical vibration only, using the ISO 5007 Standard [1]. This paper describes the laboratory vibration tests using a MTS® shaker table and discusses the results obtained for the different suspension designs and highlights the rheonetic technology studied. Implications of the seat suspension designs relative to their capabilities for isolating vehicle operators from vibration exposure are discussed. Results for suspensions 1 through 3 showed frequencies of isolation from 2.1 to 3.0 Hz using the 40-kg (88-lb) mass and from 1.65 Hz to 1.8 Hz using the 80-kg (176-lb) mass. Suspension #4, in tests with only the 80-kg (176-lb) mass, showed an isolation frequency of 3.7 Hz. With the MR damper added to seat suspension #4, the peak transmissibility was lowered from 1.3 to 0.95 and showed a corresponding downward shift in frequency from 2.25 Hz to 1.4 Hz. In fact, the results for suspension #5 (the MR damper added to seat suspension #4), using test #3 conditions of the programmed control algorithm, showed isolation (attenuation of transmitted vibration) throughout the test frequency range from 1.0 to 6.0 Hz.

Design of Direct Drive Electro-Hydraulic Actuator Based on Internet of Things Technology

2014 ◽  
Vol 945-949 ◽  
pp. 1601-1605
Author(s):  
Long Hui Wang ◽  
Yong Wang
Keyword(s):  
Internet Of Things ◽  
Power Plants ◽  
High Efficiency ◽  
Control Valve ◽  
Display Device ◽  
Pipe Network ◽  
Direct Drive ◽  
Hydraulic Actuator ◽  
Internet Of Things Technology ◽  
Hydraulic Valve

Direct drive electro-hydraulic actuator is a new type of hydraulic transmission with easy maintenance and high efficiency, which has been widely used in municipal engineering (such as water pipe network, gas pipe network), nuclear power plants, and other occasions. For these applications, we designed the electro-hydraulic valve actuator based on Internet of things technology (IOT for short). This paper introduces the mechanical structure and the working principle of the direct-drive electro-hydraulic valve actuator, analyzes IOT architecture. Detailed design was carried on according to the IOT architecture and related experiments have been done. The actuator can automatically, accurately control valve opening, be monitored by PC remotely, display device real-time information through LCD and be operated by touch screen.

Reliability and Availability Prediction of Main Stop Valve and Control Valve Systems of Steam Turbines

2011 ◽  
Author(s):  
Jinyuan Shi ◽  
Yong Wang ◽  
Xiaoping Zhong ◽  
Zhicheng Deng
Keyword(s):  
Prediction Method ◽  
Control Valve ◽  
Design Stage ◽  
Steam Turbines ◽  
Stop Valve ◽  
Control Valves ◽  
Reliability Block Diagrams ◽  
And Control ◽  
The Mathematical Model ◽  
Reliability And Availability

A method for the reliability and the availability prediction of main stop valve and control valve systems of steam turbines is presented. The calculation models for the reliability and the availability of series, parallel and series-parallel systems of main stop valves and control valves are introduced. The reliability block diagrams, the availability block diagrams, formulas for the reliability prediction and the availability prediction of systems with 2 main stop valves and 2 control valves, 2 main stop valves and 4 control valves, 2 main stop valves and 6 control valves, 4 main stop valves and 4 control valves are given together with some examples. The mathematical model for the reliability and the availability prediction method of main stop valve and control valve systems of steam turbine is simple and the physical meaning is definite. The reliability and availability of main stop valve and control valve systems can be quantitatively already calculated and improved during the design stage. A basis is thus provided for the reliability and the availability design of main stop valve and control valve systems of steam turbines.

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