Patent ID: 8214083

Claim:
A manipulator comprising: an elongated tube body including a bendable bending portion; a bending wire provided at the tube body for a bending operation of the bending portion; a motor including a rotary shaft which rotates in accordance with a current command signal; a reduction gear unit connected to the rotary shaft and configured by a plurality of gears meshing with each other for changing velocity with respect to a rotational velocity of the rotary shaft; a connection portion which connects a proximal end of the bending wire and the reduction gear unit for operating the bending portion; a motor angle detection unit which detects a rotational angle of the motor rotationally driven in accordance with the current command signal; a reduction-gear-unit angle detection unit which detects a rotational angle of the reduction gear unit driven by the motor which is rotationally driven; a torque information calculation section which calculates information of torque generated on the rotary shaft based on the rotational angle of the motor; an estimated torque calculation section which calculates estimated torque information supposed to be generated on the rotary shaft by supplying the current command signal to a motor model of the motor; a disturbance torque calculation section which calculates a difference between the torque information and the estimated torque information as information of disturbance torque generated on the rotary shaft; a position data generation section which generates meshing positions of the plurality of gears as position data based on the rotational angle of the motor and the rotational angle of the reduction gear unit; a storage unit which stores torque variation to be interposed with the disturbance torque to correspond to the position data and the disturbance torque information, as correction information in advance, the torque variation being periodically caused on the rotary shaft of the motor by the meshing of the plurality of gears constituting the reduction gear unit; and a tube body load calculation section which obtains the correction information from the storage unit and makes an operation for a load torque generated on the rotary shaft of the motor by a load exerted on the tube body, the load torque being obtained by correcting the disturbance torque information based on the correction information.