Robot Force Feedback Using Virtual Reaction Force for Contact Sensing
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Solution Overview
Problem
Conventional robot systems have limited tactile sensing capabilities, making it difficult to perform high-precision tasks such as surgical operations and component fitting, as they only provide feedback on reaction forces, lacking sensitivity in detecting contact with objects.
Innovation Solution
A robot system that includes a force sensing device capable of detecting forces in three perpendicular axes and moments, generating both actual and virtual reaction-force information, which is combined to provide synthetic feedback to the operator, enhancing tactile sensing and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only actual reaction force feedback is provided to the operating device, then the system structure remains simple, but the operator cannot sensitively detect contact between the end effector and the object
Solution Approach 1:
The patent introduces virtual reaction-force information as an intermediary element that mediates between the actual reaction force and the operator's perception. This virtual information, generated through time differentiation, acts as a signal amplifier that enhances the operator's ability to detect contact without requiring complex hardware modifications. The virtual reaction-force serves as a mediator that translates subtle physical changes into perceptible feedback.
Solution Approach 2:
The patent transforms the reaction force parameter by applying time differentiation to generate virtual reaction-force information. This parameter transformation converts static force magnitude into dynamic rate-of-change information, which is more sensitive to contact events. By changing the parameter representation from force magnitude to force derivative, the system achieves enhanced contact detection sensitivity.
2Ease of operation
If virtual reaction-force information based on time differentiation is added to enhance contact sensitivity, then contact detection sensitivity improves, but the information processing complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where virtual reaction-force information derived from time differentiation of actual reaction force is fed back to the operating device. This feedback loop provides the operator with enhanced tactile information about contact dynamics, improving operability in high-precision tasks. The synthesized feedback combining actual and virtual reaction forces creates a more informative control loop.
3Reliability
If only force magnitude information is provided, then the feedback system remains simple, but the operator cannot sense the dynamic characteristics of contact
Solution Approach 1:
The patent addresses information loss by transforming the force parameter through time differentiation. This parameter change extracts dynamic characteristics from the force signal, converting static magnitude information into dynamic rate-of-change information. The transformation preserves and emphasizes transient contact information that would be imperceptible in static force measurements alone.
Solution Approach 2:
The system performs preliminary processing of the reaction force signal by calculating its time derivative before presenting it to the operator. This preliminary action of differentiation prepares the information in a form that highlights dynamic contact characteristics, enabling the operator to sense contact events more reliably before they become significant force magnitudes.
Data Source
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AI summary
A robot system includes a robot main body including a robot arm, an end effector attached to the robot arm, and a force sensing device configured to detect a force applied to a tip end of the end effector, an actual reaction-force information generator configured to generate force-sensing information according to the force detected by the force sensing device, and output the force-sensing information as actual reaction-force information, a virtual reaction-force information generator configured to output a component of the force detected by the force sensing device, that has a magnitude proportional to a time differentiation value, as virtual reaction-force information, an adder configured to output information obtained by adding the actual reaction-force information outputted from the actual reaction-force information generator to the virtual reaction-force information outputted from the virtual reaction-force information generator, as synthetic reaction-force information, an operating device configured to output, when an operator is made to sense a force according to the synthetic reaction-force information outputted from the adder and the operator operates, operating information according to the operation, and a motion controller configured to control operation of the robot main body according to the operating information outputted from the operating device.