Robot Torque Sensor Temperature Compensation and Motion Limiting

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Solution Overview

Problem

The accuracy of torque sensors in robots is compromised by temperature fluctuations due to heat generation, surrounding environmental temperatures, and operational loads, leading to inaccurate torque data detection and potential safety risks during cooperation with humans.

Innovation Solution

A robot system equipped with a torque sensor that includes a temperature detection unit and a temperature compensation unit, along with a sensor temperature determination unit, to monitor and adjust operations based on the torque sensor's temperature state, ensuring accurate torque data and safe human-robot interaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the robot is designed with high airtightness for dust resistance, water resistance, and electric noise protection, then reliability is improved, but heat dissipation deteriorates causing torque sensor temperature increase

Engineering Contradiction:

Improvedust resistance, water resistance, electric noise protectionVSAvoidtorque sensor temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

A heat dissipation plate is introduced as an intermediary component between the torque sensor and the external environment. The plate conducts heat away from the torque sensor through thermal conduction while the airtight housing maintains protection against dust, water, and electric noise. This mediator allows heat to escape without compromising the sealed structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the torque sensor is closely attached to the driving unit to improve measurement accuracy, then measurement precision is improved, but heat transmission from the driving unit to the torque sensor increases

Engineering Contradiction:

Improvetorque measurement accuracyVSAvoidtorque sensor temperature

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The housing structure is designed with differentiated thermal properties in different regions. The region near the torque sensor incorporates heat dissipation pathways and thermal insulation features, while maintaining close attachment to the driving unit for accurate torque measurement. This local quality approach allows simultaneous achievement of measurement precision and thermal management.

Inventive Principle:

Principle #3Local quality

3Productivity

If the robot operates at high speed and high acceleration to improve productivity, then productivity is improved, but heat generation increases causing torque sensor overheating

Engineering Contradiction:

Improveoperation speed and accelerationVSAvoidtorque sensor temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The heat dissipation system operates continuously through the housing structure and heat dissipation plate, providing constant thermal management regardless of the robot's operational state. This continuous heat removal capability allows the robot to maintain high productivity operations without causing torque sensor overheating, as the thermal management system is always active rather than intermittent.

Inventive Principle:

Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system provides accurate torque data compensation and ensures safe operation by adjusting speed and acceleration based on the torque sensor's temperature state, enhancing detection accuracy and preventing overheating-related safety issues.

Implementation Method 1

a temperature detection unit, and a temperature compensation unit that obtains data subjected to temperature compensation, based on an output value of the torque detection unit and an output value of the temperature detection unit

Methodology Applied

Scientific EffectTemperature detection:

Implementation Method 2

a temperature compensation unit that obtains data subjected to temperature compensation, based on an output value of the torque detection unit and an output value of the temperature detection unit

Methodology Applied

Scientific EffectTemperature compensation:

Implementation Method 3

a sensor temperature determination unit that determines whether a temperature state of a torque sensor is an abnormal state and whether a temperature state of a torque sensor is an appropriate temperature state, based on an output value of at least one of the temperature detection unit and the temperature compensation unit

Methodology Applied

Scientific EffectTemperature state determination:

Data Source

PatentUS12515324B2Robot system comprising robot including torque sensors

Publication Date: 2026.01.06 FANUC LTD

AI summary

This robot system includes a robot that includes torque sensors corresponding to joint axes. The robot system includes a sensor temperature determination unit that determines whether the temperature state of each of the torque sensors is an abnormal or appropriate temperature state on the basis of an output value of a temperature detection unit. The robot system includes an operation command unit that reduces at least one among the speed and the acceleration of a robot drive motor when there is a torque sensor of which the temperature state is an abnormal temperature state and not an appropriate temperature state.