A German-based start-up company has developed a non-contact torque sensing technology that, it claims, overcomes the limitations of existing technologies, such as dynamometers and strain gauges, at a fraction of their costs. The company, Fast Technology, estimates that there is a potential market for 200 million of its sensors a year in applications ranging from machine controls to power steering systems on vehicles.
Fast`s technique - on which there are 20 patents pending - is to magnetise the shaft and to sense the changes in the magnetic field that occur when torque is applied. These changes are detected by a sensing head typically placed about 1mm from the shaft, and are then converted into an electrical signal by conditioning electronics.
Fast says that the technique is unaffected by the presence of dirt and fluids, or by the speed of the shaft, which can be stationary or spinning at up to 100,000 rpm. The sensing range is 0.5-100mm and typical accuracy is claimed to be 0.5% of full scale.
Potential industrial applications include:
• controlling the forces applied in machine tools;
• regulating web tensions in paper and textile production; and
• monitoring torque levels in electrical and pneumatic wrenches.