Motor Sensor Device Back-EMF Detection Circuit
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Solution Overview
Problem
Existing sensor technologies face challenges in detecting gentle contact and small external forces in robotic devices, as they often require high-precision sensors that are difficult to implement due to noise interference and increased size and power consumption.
Innovation Solution
A sensor device with a backflow prevention unit in the motor circuit that converts back electromotive force into a potential difference, allowing for the detection of small external forces by measuring the potential difference between the preceding and subsequent stages of the backflow prevention unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If encoder-based contact detection is used, then contact detection function is provided, but gentle contact cannot be detected and detection sensitivity decreases
Solution Approach 1:
The patent replaces the mechanical encoder-based detection system with an electrical circuit-based detection system. By monitoring voltage changes in the motor's power supply circuit caused by back electromotive force (back-EMF) generated during gentle contact, the system achieves higher detection sensitivity without mechanical sensors. This substitution enables detection of subtle external forces that would not produce sufficient encoder signal changes.
Solution Approach 2:
The patent introduces voltage monitoring as an intermediary measurement method. Instead of directly measuring mechanical contact through encoders, the system uses voltage changes in the electrical circuit as an intermediary indicator of external force application. The back-EMF generated during contact creates detectable voltage fluctuations that serve as a sensitive proxy for gentle contact detection.
2Measurement precision
If high-precision sensors are used to detect small external forces, then detection sensitivity improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the existing motor and its power supply circuit serve multiple functions: both actuation and sensing. The motor continues to drive the mechanical system while simultaneously generating back-EMF signals during external force application that can be detected through voltage monitoring. This multi-functionality eliminates the need for separate high-precision force sensors, reducing device complexity and manufacturing cost while maintaining detection sensitivity.
Solution Approach 2:
The motor serves itself by generating the sensing signal through its own back-EMF during external force application. Instead of requiring external sensors to detect small forces, the system uses the motor's inherent electrical characteristics - specifically the back-EMF generated when external forces resist its rotation - to provide the detection function. This self-service approach simplifies the overall system architecture.
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
This approach enhances the detection sensitivity for small external forces without the need for additional sensors, simplifying the robotic device structure and reducing manufacturing costs while maintaining accurate contact detection.
Implementation Method 1
a back electromotive force of a motor generated by an external force can be detected by converting the back electromotive force into a potential difference between a preceding stage and a subsequent stage of the backflow prevention unit
Data Source
AI summary
A sensor device and a sensing method capable of detecting even a small external force are provided. A sensor device includes: a backflow prevention unit provided in the middle of a circuit that supplies a current from a power supply unit to a motor unit; a potential detection unit configured to detect each of potentials at a preceding stage and a subsequent stage of the backflow prevention unit; and an external force detection unit configured to detect an external force applied to a member connected to the motor unit on the basis of the potentials at the preceding stage and the subsequent stage of the backflow prevention unit.