System, robot and robot system for detecting load applied to robot

• US 9,946,248 B2
• Filed: 10/22/2015
• Issued: 04/17/2018
• Est. Priority Date: 10/23/2014
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Nakayama, Kazutaka, Iwayama, Takatoshi
• Primary Examiner(s): Jen, Ian
• Application Number:
  US14/920,168
• Publication Number:
  US 20160114484A1
• Time in Patent Office: 908 Days
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: G05B 19/4062 Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference
• CPC Class Codes: Y10S 901/09 Closed loop, sensor feedback controls arm movement

Abstract

A system which can improve the reliability of an emergency stop operation of a robot when contacting a worker. The system is comprised of a force sensor and a malfunction judgment part. The force sensor has a detection part which detects the load in one direction. The detection part includes a first detection element and a second detection element. The malfunction judgment part judges if a first detection value which is detected by the first detection element and a second detection value which is detected by the second detection element differ from each other. If the first detection value and the second detection value differ from each other, it is judged that the first detection element or second detection element have malfunctioned.

Claims

1. A system for detecting a load applied to a robot, comprising:

a force sensor including a detection part which detects a load in a direction, the detection part including a first single-axis detection element for detection in one axis direction and a second single-axis detection element for detection in the one axis direction; and

a malfunction judgment part which

judges whether a first detection value detected by the first detection element and a second detection value detected by the second detection element are different from each other, and which judges that the first detection element or the second detection element malfunctions when the first detection value and the second detection value are different from each other.

2. The system according to claim 1, wherein the malfunction judgment part calculates a difference between the first detection value and the second detection value, and judges that the first detection value and the second detection value are different from each other when the difference exceeds a predetermined threshold value.

3. The system according to claim 1, wherein the malfunction judgment part calculates a difference between a first force calculated from the first detection value and a second force calculated from the second detection value, and judges that the first detection value and the second detection value are different from each other when the difference exceeds a predetermined threshold value.

4. The system according to claim 1 wherein the first detection element and the second detection element are arranged so as to align with each other.

5. The system according to claim 1, wherein the first detection element is a detection element of a type different from the second detection element.

6. A robot comprising:

a robot arm; and

a system according to claim 1, wherein

the force sensor is attached to the robot arm.

7. A robot system comprising:

a robot according to claim 6; and

a controller which controls the robot, wherein

the controller stops the operation of the robot when the malfunction judgment part judges that the first detection element or the second detection element malfunctions.