Abstract: A multi-turn absolute encoder, an encoding method and a robot are disclosed. The multi-turn absolute encoder includes a rotary shaft, a control circuit board, a magnet, a Hall sensor, a controller, a primary controller, a single-turn absolute encoder and a non-volatile memory. One side of the control circuit board is vertically provided with the rotary shaft. The magnet is connected to the rotary shaft and configured to synchronously rotate about the rotary shaft. The Hall sensor is configured to acquire turn count information of the rotary shaft upon power interruption. The primary controller is configured to calculate an absolute position information of the rotary shaft based on the turn count information of the rotary shaft, a relative position information of the rotary shaft and the absolute position information of the rotary shaft stored in previous power interruption.

Abstract: An actuator, a robot arm and a robot are disclosed. The actuator includes: a motor, including a housing, a motor stator and a motor rotor, wherein the motor stator is disposed to the housing, the motor rotor is rotatably connected to the housing, and the motor rotor covers the motor stator; a position encoder, disposed to the motor rotor; a reducer, connected to the motor rotor, and configured to adjust a rotation speed output from the motor rotor; and a motor driver, disposed on the housing, and electrically connected to the motor.