A new absolute magnetic encoder with big hallow

To measure the angular position of motors, robot joints, etc, an absolute magnetic rotary position sensor is developed, which possesses advantages of large central-hole, small-size, compact structure, high resolution, absolute output and so on. The sensor consists of two code disc and a signal processing board. To measure absolute angular position, a method based on the vernier caliper measuring principle is proposed. The magnetic field and the mode of the rotor are analyzed by using the simulation software. In order to improve the output precision of magnetic encoder, a new error compensation model based on genetic algorithm is proposed and the calibration platform is built. At last, the experimental results indicate that the accuracy of the sensor can reach up to 0.2 degrees, while the positioning accuracy can reach 0.036 degrees after the compensation. These accuracies can fully fill the requirements of robot joint servo system.