US Patent No. 9,327,408

ROBOT CONTROL DEVICE DETECTING CONTACT WITH EXTERNAL ENVIRONMENT


Patent No. 9,327,408
Issue Date May 03, 2016
Title Robot Control Device Detecting Contact With External Environment
Inventorship Yasuhiro Naitou, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,327,408

1. A robot control device for controlling an articulated robot to which a force sensor is attached, comprising:
an internal force estimating unit for estimating a force generated at a point where the force sensor is attached as an internal
force, based on the weight of each of a robot arm and a hand attached to the tip of the robot arm in a state in which the
robot arm of the robot is not in contact with an external environment, and an inertial force generated by the operation of
each of the robot arm and the hand;

a storage unit in which each rotational operation region of a plurality of joints of the robot arm is divided into a plurality
of small regions depending on the angle, and for each of the small regions, an internal force estimated by the internal force
estimating unit is subtracted from an output of the force sensor in a state in which the robot arm is not in contact with
an external environment, thereby storing a force correction amount;

a force correction amount determining unit in which a force correction amount corresponding to each of the current angles
of the plurality of joints of the robot arm is determined by the storage unit; and

a contact force calculating unit in which a contact force when the robot arm is in contact with an external environment is
calculated by subtracting an internal force estimated by the internal force estimating unit and the force correction amount
determined by the force correction amount determining unit from a current output of the force sensor.