Emergency shutdown system for controlling industrial robot

• US 5,363,474 A
• Filed: 03/18/1993
• Issued: 11/08/1994
• Est. Priority Date: 05/21/1991
• Status: Expired due to Term

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Kurenuma, Toru, Andoh, Takeshi, Sarugaku, Shinichi, Kawasaki, Kyoichi, Otomo, Masami
• Primary Examiner(s): MacDonald, Allen R.
• Application Number:
  US08/030,291
• Time in Patent Office: 600 Days
• Field of Search: 395/90, 395/91, 395/95, 395/93
• US Class Current: 700/256
• CPC Class Codes: B25J 9/1674 characterised by safety, monitoring, diagnostic
• CPC Class Codes: G05B 19/425 Teaching successive positions by numerical control, i.e. commands being entered to control the positioning servo of the tool head or end effector
• CPC Class Codes: G05B 2219/36399 On excess error or on release joystick stop movement, dead man, shut off motors
• CPC Class Codes: G05B 2219/36473 Prohibit teaching if force, speed, acceleration of end effector is out of safe range
• CPC Class Codes: G05B 2219/42123 Position loop then force, current loop

Abstract

A system for controlling an industrial robot, which is simplified in operation and capable of direct-teaching safely all the time. The system is provided with means (131 and 132) for monitoring a magnitude of an external force applied to the forward end of a hand during direct teaching, so that the motion of the robot can be forcibly restricted when the external force reaches a predetermined value of thereabove. Furthermore, when the system is operated to be set in a direct teach mode, a process (136) of correcting the offset of a force sensor is performed automatically. By monitoring a force detected by the force sensor, the discrimination is made as to whether an external force to operate the robot at an abnormal speed is applied to the robot or not, and when the external force becomes higher than a reference value, a mode of prohibiting the operation of the robot by the external force (position control mode) is set, or current supplied to a servo motor is cut off to prevent the robot from going into the erroneous operation due to an erroneous control.

Claims

1. A system for controlling an industrial robot comprising:

sensor means for detecting an amount of external force applied to a forward end of a moving part of a main body of said robot;

means for controlling a driving force of the main body in accordance with the amount of external force detected by said sensor means, said means for controlling having a normal position control mode and a direct teach control mode; and

emergency cut-off means for cutting-off the supply of the driving force to the main body of said robot to stop the main body in an emergency when the amount of said external force exceeds a preset reference value.

2. The system for controlling an industrial robot according to claim 1, further comprising speed restricting means for restricting the moving speed of the forward end of the moving part of the main body of said robot to a preset speed value so that a speed control can be effected during operation of the direct teach control mode.

3. A system for controlling an industrial robot comprising:

sensor means for detecting an amount of external force applied to a forward end of a moving part of a main body of said robot;

means for controlling a driving force of the main body in accordance with the amount of external force detected by said sensor means, said means for controlling having a normal position control mode and direct teach control mode; and

warning display means for displaying a warning when the amount of said external force exceeds a preset reference value.

4. The system for controlling an industrial robot according to claim 3, further comprising speed restricting means for restricting the moving speed of the forward end of the moving part of the main body of said robot to a preset speed value so that a speed control can be effected during operation of the direct teach control mode.

5. A system for controlling an industrial robot comprising:

sensor means for detecting an amount of external force applied to a forward end of a moving part of a main body of said robot;

means for controlling a driving force of the main body in accordance with the amount of external force detected by said sensor means, said means for controlling having a normal position control mode and a direct teach control mode; and

direct teach control mode reset means for resetting said direct teach control mode when the amount of said external force exceeds a preset reference value.

6. The system for controlling an industrial robot according to claim 5, wherein speed restricting means for previously setting a maximum value of moving speed of the forward end of the moving part of the main body to suppress it to a certain limited speed value so that a speed control by this speed restricting means is effected in the direct teach control state.

7. A system for controlling an industrial robot comprising:

sensor means for detecting an amount of external force applied to a forward end of a moving part of a main body of said robot;

means for controlling a driving force of the main body in accordance with the amount of external force detected by said sensor means, said means for controlling having a normal position control mode and a direct teach control mode; and

offset correcting means for correcting an offset of said sensor means when the control mode of the robot is switched from said normal position control modes to said direct teach control mode.