Method and system for controlling cooperative object-transporting robot

• US 6,522,952 B1
• Filed: 04/19/2001
• Issued: 02/18/2003
• Est. Priority Date: 06/01/1999
• Status: Expired due to Fees

• Current Assignee: Agency of Industrial Science & Technology (Government of Japan)
• Original Assignee: Agency of Industrial Science & Technology (Government of Japan)
• Inventors: Hayashibara, Yasuo, Takubo, Tomohito, Sonoda, Yukinobu, Tanie, Kazuo, Arai, Hirohiko
• Primary Examiner(s): Tran, Khoi H.
• Application Number:
  US09/774,173
• Time in Patent Office: 670 Days
• Field of Search: 700/245, 700/260, 700/261, 700/258, 700/213, 901/2, 901/9, 901/14, 901/16, 901/34, 414/719, 414/591
• US Class Current: 700/258
• CPC Class Codes: B25J 13/085 Force or torque sensors B25J13/082, B25J13/084 take precedence
• CPC Class Codes: B25J 9/1679 characterised by the tasks executed
• CPC Class Codes: G05B 2219/36429 Power assisted positioning

Abstract

A control of a cooperative object-transporting robot which transports an object in cooperation with a man. The robot shares substantially a half of the weight of the object with the man, while the object is kept in a horizontal posture. A force applied to the robot by the object is detected by a force sensor, and based on the signal from the force sensor, a motion instruction is output for the motion components by the rotational force component τ₁ around the horizontal axis and the translational force component Fx₁ in the horizontal back-and-forth direction, upon setting a gain to reduce the resistance forces of the robot to small values. The translational force component F_y in the direction of the object short axis is constrained so that no translational motion in the direction of the object short axis occurs.

Claims

1. A method for control a cooperative object-transporting robot, in which a man and a robot transport a long object or a large-sized object in a horizontal plane while grasping each of the ends of the object, wherein:

a force applied to the robot by the object is detected by a force sensor, and based on the rotational force component around the vertical axis, and the translational force component in the direction of the object long axis obtained by connecting the point grasped by the man and the point grasped by the robot, each of which is separated from the sensor signal, said rotational motion component around the vertical axis and said translational motion component in the direction of the object long axis are output, upon setting a gain so as to reduce the resistance forces of the object to small values, while the translational force component in the direction of the object short axis orthogonal to said object long axis is constrained so that no translational motion in the direction of the object short axis occurs,

whereby a motion limitation equivalent to the object being supported by a virtual wheel facing the direction of the object long axis, at one point on the robot side, is imposed on the object, and then the robot arm is driven.

2. A method as claimed in claim 1, wherein:

an angle of the hand-tip of the robot is detected by angle sensors, and based on the sensor signals, a motion instruction for a translational motion of the hand-tip in the vertical direction is output so as to keep the posture of the object horizontal.

3. A system for control a cooperative object-transporting robot, in which a man and a robot transport a long object or a large-sized object in a horizontal plane while grasping each of the ends of the object, said system comprising:

a force sensor for detecting a force applied to the robot by the object;

a coordinate converting part for separating, from the sensor signal, the rotational force component around the vertical axis, the translating force component in the direction of the object long axis obtained by connecting the point grasped by the man and the point grasped by the robot, and the translating force component in direction of the object short axis orthogonal thereto;

a force-motion converting part which, based on said rotational force component around the vertical axis and said translational force component in the direction of the object long axis, outputs these motion components, using a gain such as to reduce the resistance forces of the robot in these rotational direction and translation direction; and

a coordinate converting part for synthesizing these motion components and said translational force component in the direction of the object short axis which is set to be zero, and outputting a motion instruction to drive the robot arm.