Robot Arm Force Sensing with Coordinate Alignment Estimation
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Solution Overview
Problem
Electronic devices, such as robots, face inaccuracies in measuring external forces due to errors in attaching force sensors, leading to unnatural compliance and response, as the force sensors' coordinate systems may not align perfectly with the device's coordinate systems.
Innovation Solution
An electronic device with a robot arm, actuator, and processor that receives multiple measurement values from a force sensor at different positions to estimate the relationship between coordinate systems, allowing for accurate calculation of external forces by compensating for attachment errors and biases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the force sensor is detachable for ease of installation and maintenance, then the ease of operation is improved, but the measurement precision deteriorates due to attachment errors in coordinate system alignment
Solution Approach 1:
The patent applies preliminary action by pre-defining a predetermined coordinate system at the coupling portion before the force sensor is attached. This predetermined coordinate system serves as a reference that remains consistent regardless of attachment variations. The processor uses this predetermined coordinate system to accurately calculate external forces even when the force sensor's actual coordinate system deviates due to attachment errors, thus maintaining measurement precision while allowing detachable installation
Solution Approach 2:
The patent introduces an intermediary coordinate transformation mechanism. Instead of directly using the force sensor's coordinate system, the processor transforms measurement values from the force sensor's coordinate system to the predetermined coordinate system of the coupling portion. This coordinate transformation acts as an intermediary that compensates for attachment errors and ensures accurate force calculation regardless of attachment precision
2Measurement precision
If the force sensor is fixed with a predetermined coordinate system, then the measurement precision is improved, but the adaptability deteriorates when attachment errors occur
Solution Approach 1:
The patent applies dynamics by making the coordinate system adaptation dynamic rather than static. The processor dynamically adjusts for attachment errors by transforming measurement values from the force sensor's coordinate system to the predetermined coordinate system of the coupling portion. This dynamic coordinate transformation allows the system to adapt to various attachment conditions while maintaining measurement precision, thus achieving both precision and adaptability
Data Source
AI summary
Disclosed is an electronic device including a robot arm configured to include at least one coupling portion configured to be coupled to a force sensor to which a specified object is attached, at least one actuator configured to drive the robot arm such that a position of the at least one coupling portion is changed, and a processor electrically connected to the actuator, wherein the processor is configured to: receive a first measurement value of the force sensor due to a weight of the specified object with respect to a first position of the at least one coupling portion, receive a second measurement value of the force sensor due to the weight of the specified object with respect to a second position of the at least one coupling portion, receive a third measurement value of the force sensor due to the weight of the specified object with respect to a third position of the at least one coupling portion, and estimate a relationship between a first coordinate system relative to the at least one coupling portion and a second coordinate system relative to the force sensor based at least on at least the first measurement value, the second measurement value, and the third measurement value to calculate a magnitude of an external force acting on the specified object.