Robot Joint Stopper Layout to Protect Torque Sensors

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Solution Overview

Problem

Existing robots equipped with torque sensors are prone to damage when an impact force exceeds the allowable deformation range, particularly when a mechanical stopper collides with the robot arm, as the torque sensor is deformable and cannot sufficiently decrease the impact force.

Innovation Solution

Incorporating a first and second stopper mechanism that limits the movable range of the robot's links and transmission members, preventing direct transmission of large impact loads to the torque sensor by ensuring a clearance between these components, thereby reducing the risk of sensor damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical stopper is provided to limit the movable range of the robot, then the risk of collision damage is reduced, but the impact force can still damage the torque sensor

Engineering Contradiction:

Improverisk of collision damageVSAvoidimpact force to torque sensor

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A stopper is provided on the transmission member (intermediary component) rather than directly on the link, creating a buffer between the mechanical stop and the torque sensor. When the robot approaches its movement limit, the stopper on the transmission member contacts the link's stop, preventing excessive movement while isolating the torque sensor from direct impact forces through the transmission mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The stopper function is segmented between two components: a stopper on the link and a stopper on the transmission member. This segmentation allows the transmission member's stopper to absorb and distribute the impact force through the transmission mechanism, preventing concentrated impact on the torque sensor while still limiting the robot's movable range.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the robot limits its movable range using a stopper, then peripheral apparatus damage is prevented, but the torque sensor may still be damaged by impact forces

Engineering Contradiction:

Improveprotection of peripheral apparatusVSAvoidtorque sensor durability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The stopper on the transmission member acts as an intermediary that limits the robot's movable range to prevent peripheral apparatus damage, while simultaneously serving as a protective buffer that prevents direct transmission of impact forces to the torque sensor, thus protecting both the peripheral apparatus and the sensor.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The stopper mechanism provides beforehand cushioning by limiting the robot's movement range before excessive impact can occur. The stopper on the transmission member is positioned to engage with the link's stop at the boundary of the safe movable range, cushioning the system against future impact forces that would otherwise damage the torque sensor or peripheral apparatus.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a stopper is provided on the link to limit movement, then collision risk is reduced, but the torque sensor cannot sufficiently decrease the impact force

Engineering Contradiction:

Improvecollision risk reductionVSAvoidimpact force transmission

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

By placing the stopper on the transmission member rather than directly on the link, the system introduces an intermediary element that limits collision risk while preventing direct impact force transmission to the torque sensor. The transmission member's stopper engages with the link's stop to limit movement, but the force is distributed through the transmission mechanism rather than directly impacting the sensor.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The stopper function is extracted from the link and placed on the transmission member. This extraction removes the direct connection between the stopper and the torque sensor, allowing the stopper to limit movement and reduce collision risk while the transmission mechanism absorbs and distributes the impact forces, preventing them from reaching the sensor.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12583105B2Robot, control method therefor, method for manufacturing article using robot, and storage medium

Publication Date: 2026.03.24 CANON KK

AI summary

A robot includes a first link, a driving device configured to cause the first link to rotate, a transmission member configured to transmit a rotation of the driving device, a first stopper provided on the first link, and a second stopper provided on the transmission member, wherein the first stopper and the second stopper are brought into contact with each other by a relative movement between the first link and the transmission member.