Inceptor Force Drift Compensation Through Hands-Off Detection

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Solution Overview

Problem

Active inceptor systems face performance deterioration due to slow output drift from force sensors over time, making it difficult to distinguish between user-applied forces and environmental offsets, leading to a compromised user experience.

Innovation Solution

Implementing a method to detect the hands-off status of a user input device, using lag filters and threshold comparisons to identify when the user is not interacting with the device, allowing for the application of filters to remove force offsets imperceptibly, and utilizing circuitry to compensate for drift only when the user is not present.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If force sensors are used to detect user input, then measurement capability is provided, but output drift occurs over time causing performance deterioration

Engineering Contradiction:
Improveforce detection accuracyVSAvoidsystem performance stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system performs preliminary action by detecting hands-off status and applying drift compensation filters before the drift affects measurement accuracy. The filter is proactively engaged during hands-off periods to prevent cumulative drift errors, rather than correcting after degradation occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts filter application based on real-time detection of hands-off status. The filtering component transitions between active and inactive states depending on whether the user is interacting with the device, optimizing the balance between drift compensation and user feedback accuracy.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If filters are applied to remove force offsets, then measurement accuracy is improved, but user-applied forces may be incorrectly removed affecting user experience

Engineering Contradiction:
Improveforce offset removal accuracyVSAvoiduser experience quality
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system uses feedback from hands-off status detection to control filter application. The detection component continuously monitors whether the user is interacting with the device and feeds this information to the filtering component, which adjusts its operation accordingly - applying filters only when hands-off status is detected, thus avoiding interference with user-applied forces.

Inventive Principle:
Principle #23Feedback

3Reliability

If drift compensation is applied continuously, then sensor drift is corrected, but user-applied forces are incorrectly compensated reducing system responsiveness

Engineering Contradiction:
Improvedrift compensation effectivenessVSAvoidsystem response speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The system dynamically switches drift compensation based on hands-off status detection. The filtering component is activated only during hands-off periods when no user force is applied, and deactivated during hands-on periods to preserve full system responsiveness to user inputs, thus optimizing both drift compensation and response speed.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3996991B1Inceptor and method
Publication Date: 2024.02.28 BAE SYSTEMS PLC
  • EP3996991B1 patent drawingFigure 1
  • EP3996991B1 patent drawingFigure 2
  • EP3996991B1 patent drawingFigure 3~4

AI summary

A method to detect a hands off status of a user input device is disclosed. The method comprising filtering a sensed force, acting on the user input device, using a first lag filter to provide a first output, the lag filter comprising a first lag time constant. Filtering the sensed force using a second lag filter, substantially in parallel with the first filter, to provide a second output, the second lag filter comprising a second lag time constant greater than the first lag time constant. Comparing with a first threshold value, in a first comparison, a magnitude of a difference between the first output and the second output. Comparing with a second threshold value, in a second comparison, a magnitude of the second output. Designating the user device to have a hands off status based on the first comparison and the second comparison.