Multi-joint robot having function for repositioning arm

Abstract

A multi-joint robot using substantially one sensor, capable of performing a proper repositioning motion of an arm of the robot. The controller has a disturbance torque estimating part which estimates a first disturbance torque and a second disturbance torque, by calculating a torque generated by a mass and motion of the robot and subtracting the calculated torque from the first torque and the second torque detected by a torque detecting part. The controller has a repositioning commanding part which generates a motion command for rotating each axis so that the disturbance torque is reduced, when the disturbance torque exceeds a torque threshold. Since the axis J1 or J2 is repositioned based on the motion command, a portion of the robot pushed by the operator is repositioned, whereby the operator can easily perform one's work without using a teaching board, etc.

Description

technical field [0001] The present invention relates to an articulated robot having at least two axes and having a backward function of an arm. Background technique [0002] In recent years, collaborative robots that work in a shared work area with humans without using safety fences or the like have become popular. Such a collaborative robot may be configured to stop its motion when a human approaches or touches the collaborative robot in order to ensure the safety of the human. [0003] However, since the working area of ​​the collaborative robot is shared with human beings, the stopped robot may interfere with the work of human beings. In such cases, it is desirable to make the robot move backward. There are cases where, as the method of this retreat, instead of using the operation using the teaching pendant, it may be easier for a human to directly push the robot. [0004] As a prior art related thereto, Japanese Patent Application Laid-Open No. 08-071969 describes that...

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Problems solved by technology

[0006] In Japanese Patent Application Laid-Open No. 08-071969, the torque acting on the shaft is calculated using the motor current, but in this method, the calculated torque includes the influence of friction, and the correct torque cannot be obtained. Happening

As a result, there are cases where the direction and force of a person's push cannot be accurately detected.

[0007] On the other hand, as described in Japanese Patent Application Laid-Open No. 10-291182, when a torque sensor is provided for each arm, the influence of friction can be eliminated, but the number of torque sensors corresponding to the number of arms (shafts) is required. moment sensors, so especially in articulated robots, the cost increases

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