Rehabilitation device with variable resistance and intelligent control.

This paper reviews the state of the art of directly driven proportional directional hydraulic spool valves, which are widely used hydraulic components in the industrial and transportation sectors. First, the construction and performance of commercially available units are discussed, together with simple models of the main characteristics. The review of published research focuses on two key areas: investigations that analyze and optimize valves from a fluid dynamic point of view, and then studies on spool position control systems. Mathematical modeling is a very active area of research, including computational fluid dynamics (CFD) for spool geometry optimization, and dynamic spool actuation and motion modeling to inform controller design. Drawbacks and advantages of new designs and concepts are described in the paper.

A review of direct drive proportional electrohydraulic spool valves: industrial state-of-the-art and research advancements

Development of a Semi-active Intelligent Suspension System for Heavy Vehicles

The real “golden age” of electronic suspension can be probably located in the 1980s; during that decade the exceptional potential of replacing a traditional spring-damper system with a fully fledged electronically controllable fast-reacting hydraulic actuator was demonstrated. High costs, significant power absorption, bulky and unreliable hydraulic systems, and uncertain management of the safety issues: the fatal attraction for fully active electronic suspensions lasted only a few years. In the second half of the 1990s, a new trend emerged: it became increasingly clear that the best compromise of cost (component cost, weight, electronics and sensors, power consumption, etc.) and performance (comfort, handling, safety) was to be found in the technology of electronically controllable suspensions: the variable-damping suspension or, in brief, the semi-active suspension. After a decade this technology is still highly promising and attractive: it has been introduced in the mass-market production of cars; it is...

An investigation on semi-active suspension damper and control strategies for vehicle ride comfort and road holding

A prototype rehabilitation device with variable resistance and joint motion control.

A generic non-linear dynamic model of a direct-acting electrohydraulic proportional solenoid valve is presented. The valve consists of two subsystems—a spool assembly and one or two unidirectional proportional solenoids. These two subsystems are modelled separately. The solenoid is modelled as a non-linear resistor-inductor combination, with inductance parameters that change with current. An innovative modelling method has been used to represent these components. The spool assembly is modelled as a mass-spring-damper system. The inertia and the damping effects of the solenoid armature are incorporated in the spool model. The model accurately and reliably predicts both the dynamic and steady state responses of the valve to voltage inputs. Simulated results are presented, which agree well with experimental results.

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C R Gentle

Papers

A parsimonious model for the proportional control valve