Cobot Load Compensation Using Intent Detection and Force Estimation

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Solution Overview

Problem

Existing assistance exoskeletons require knowledge of the load weight for handling, which is impractical and limits their ability to handle loads of varying weights without user constraints.

Innovation Solution

A control method for an actuator that detects the user's intention to handle a load, applies an increasing command to estimate the opposing force, and uses this estimate for force servocontrol, eliminating the need for pre-measured load weight information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If force servocontrol is used with known load weight, then compensation force can be calibrated, but the system requires pre-knowledge of load weight which limits adaptability

Engineering Contradiction:

Improveability to handle loads of various weightsVSAvoidrequirement for load weight measurement and calibration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system performs self-calibration by automatically detecting load weight through the user's natural interaction. When the user attempts to move the load, the actuator measures the opposing force and autonomously determines the load weight without external intervention or manual calibration procedures.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system performs preliminary calibration action automatically during the initial interaction phase. Before normal operation begins, the actuator executes a calibration sequence where it applies increasing command and detects the opposing force to pre-determine the load weight, so that subsequent operations can proceed without constraints.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If load weight is measured beforehand, then correct compensation force can be applied, but this requires impractical operations and user constraints

Engineering Contradiction:

Improveaccuracy of compensation forceVSAvoiduser constraints and measurement operations

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system uses feedback from the user's natural interaction with the load to automatically determine load weight. The actuator monitors the opposing force during movement attempts and uses this feedback information to calculate the correct compensation force, eliminating the need for manual measurement while maintaining accuracy.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces manual load weight measurement mechanisms with an automated sensing and calculation system. Instead of requiring physical scales or manual weighing procedures, the system uses the actuator's force sensors and control algorithms to electronically determine load weight through the user's natural handling actions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12042456B2Method for automatic load compensation for a cobot or an upper limb exoskeleton

Publication Date: 2024.07.23 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A control method for controlling an actuator (11) connected to a load (50) for handling, the method comprising the steps of:detecting an intention to handle the load (50);applying an increasing command to the actuator (11) until detecting a movement of the actuator (11);storing the value reached by the command when a movement of the actuator (11) is detected;using the stored value reached by the command to determine an estimate of the opposing force exerted by the load (50) for handling; andcontrolling the actuator by means of a force servocontrol relationship using the estimate of the opposing force exerted by the load (50) for handling in order to establish the commands to be applied to the actuator (11).A cobot (1) arranged to perform the method.