Sensor-actuator challenges existing linear technologies

A West Yorkshire company has launched a short-stroke linear actuator technology which incorporates a sensor to provide ultra-fine positional control. Keighley-based NSF Controls claims that the servo linear positioner (SLP) -- which it is making under licence from the inventor, Roger Sidey -- provides a combination of performance and functions that is not possible with existing technologies such as solenoids, moving coil motors, motorised screws or pneumatic cylinders.

The SLP, which can be used as an actuator, sensor or position controller, is said to deliver a positional resolution of up to 1µ (depending on the stroke range) and a response time of 10—20ms. Strokes of up to around 10mm will be possible.

The key to the new development is a rugged, compact moving magnet with a dual-function winding configuration that creates both a high-efficiency linear thrust motor and a high-performance absolute position sensor. The integrated sensor-actuator is mechanically simple and has just four electrical connections. It is also electrically symmetrical, helping to deliver a stable temperature performance.

The actuator couples directly to the driven parts to provide continuous, wear-free operation, even under arduous conditions. A simple, adaptable interface allows either digital or analogue control.

As well as replacing and upgrading conventional technologies in existing applications, NSF predicts that the SLP`s sensory feedback capabilities will open up new design possibilities. For example, it could add greater controllability to solenoid applications, as well as avoiding impacts. It could also be used in: valve and regulator control applications with real-time system conditioning or fault monitoring; actuators operating in hazardous environments or extreme temperatures; variable displacement pumping and metering system actuators; and servo force transducers.