Posted to News on 1st Mar 2012, 00:00
Smart PID system is driving a revolution in intelligent damping
An innovative intelligent damping technology emerging from Germany offers electronically adjustable damping with reaction times measured in milliseconds.
>Combining smart PID systems and the latest in electrorheological fluid (ERF), a new intelligent damping technology uses an autonomous system that continuously monitors and modifies resistance forces within the damper. Achievable by digitally managing an electronic input signal to change the ERF fluid's viscosity within the damper, this system offers instantaneous control of dynamic damping requirements with infinite adjustment possibilities.
>Highly energy efficient with low power consumption (24V DC), damping can be adjusted using a variety of digital controls which can include 0-4V analogue, a standard PWM signal or a 24V DC SPS. Silent in operation with no 'laminar flow' or 'whistling' noises, the system has no movable parts, ensuring maintenance free operation. With a wide adjustable range of forces between 100 and 2500N through strokes ranging from 25mm to a maximum of 125mm, accurate positioning is achievable to within 0.1mm.
>Developed by Bansbach and available through its UK distributor, Albert Jagger, the easyERF damping technology was initially developed for 'active suspension' systems within the top marque automotive sector. It was immediately recognised that the technology had a much broader scope of possibilities, particularly within industrial sectors involving machine suspensions, precise motion control actuators or self adaptive end-of-stroke damping elements. By incorporating Smart PID Systems it is possible to dramatically improve performance efficiencies of a diverse range of applications which could include automated handling equipment such as conveyors, crushers, dryers or centrifuges; production machinery involved in drilling, forming, or milling; or even within the medical equipment arena such as exercise machines typically used in resistance training for heart attack patients or victims of congenital or acquired limb loss.
>Electrorheological fluids (ERF) belong to the group of Bingham materials and are dispersions consisting of oil (mineral or silicon oil) and solid polymer particles. The viscosity of such fluids can be modified by the application of an electrical charge. The greater the charge, the greater the viscosity, even to the point of solidifying liquids. Fully reversible, this effect of changing the fluid's properties is achievable within a few milliseconds. The ERF fluid remains unaffected by the number of times its viscosity changes and Bansbach easyERF dampers have been tested to over half a million cycles with no signs of deterioration.
>Smart Proportional Integral Derivative (PID) Systems consist of at least one adjustable easyERF damping cylinder and one amplifier with an integrated controller. In its basic form this open loop system involves manually managing the controller to modify the damping properties. For autonomous closed loop systems control measurement elements such as sensors can easily be integrated into the system to measure parameters such as acceleration, displacement and weight. The possibilities here are limited only by the imagination of the design engineers.
>Inside the easyERF system
>The system consists of a piston with a defined annular gap between housing and piston, and two chambers filled with silicon based electrorheological fluid. With no electrical charge applied the fluid flows through an annular valve as in a standard damper. The inherent resistance is caused by the hydraulic drag coefficient of the laminar fluid flow. On application of an electrical charge the viscosity of the fluid increases thus choking the annular valve, resulting in an increase in the resistance force of the damper. A special feature of a smart PID system is that by increasing the electrical field to it's maximum the ERF solidifies resulting in a total blocking of mass movements, achieving 'zero velocity' or 'clamping'. Key advantages of the technology include continuous force control, excellent dynamics, the availability of holding force, remote control, improved efficiency, silent acoustics and maintenance-free operation.
>The technology has almost unlimited potential to deliver improved systems design. One example would be to incorporate a slow reading sensor typically found on conveyors to monitor weights. The weight of the load is transmitted to a computer, which calculates the electrical signal to send to the easyERF damper which is acting as an end stop to arrest the load's movement. This would deliver a significant increase in productivity as conveyor speeds could be considerably increased, because no human intervention is required to mechanically increase or decrease the end damper force.
>A fast reading example could involve a high speed industrial centrifuge where multiple vibration sensors monitor erratic vibrations within the machinery. This data is interpreted and passed to an array of easyERF dampers to damp out the machine's structural movements. This group of dampers would work independently of each other with the computer sending different voltages to each damper simultaneously. Here the centrifuge's efficiency and speed can be significantly increased as the dampers prevent structural vibrations throughout the centrifuge acceleration and speed characteristics.
