Magnetic fields generated by brakes and other sources can distort the lines of magnetic flux from the rotor, which may cause a complete breakdown in the function of the magnetic rotary encoder.
Renishaw’s OnAxis magnetic rotary encoders solve this problem. They have two core components – a small diametrically polarized magnet and a custom Hall sensor ASIC, which contains a circular array of Hall effect sensors that generate a voltage when exposed to a magnetic flux field. The ASIC detects the change in magnetic flux as the magnet rotates above it. The sensor array’s sine and cosine voltage outputs change depending on magnetic position. A fast flash interpolator converts the outputs to absolute angle position. A parallel binary or serial SSI interface presents the absolute angle position value. A QUAD B encoder signals indicate relative changes of angle position.
Because the ASIC cancels magnetic interference, it can operate in areas of high external magnetic fields and adapt to imperfections in the shape of the flux field of the actuating magnetic.
:: Design World ::
Filed Under: Encoders (rotary) + resolvers, Motion control • motor controls