Motor Shaft Position Detection Using Low-Resolution Detectors
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Solution Overview
Problem
Current methods for determining the high-resolution output shaft absolute position in robots are costly, complex, and prone to accuracy issues due to the requirement for high-resolution detectors, which increases the size and expense of the actuator, and can be unsafe during the homing process.
Innovation Solution
A device and method using low-resolution absolute position detectors on both the input and output shafts of a motor, with an offset calculation module to derive a high-resolution output shaft absolute position through a relational expression based on the initial offset, input shaft absolute position, and reduction gear ratio, allowing for accurate positioning without modifying or adding actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution absolute position detector is used on the output shaft, then the accuracy of the output shaft absolute position is improved, but the cost and size of the actuator increase
Solution Approach 1:
The position detection function is segmented between two low-resolution detectors: one on the input shaft and one on the output shaft. The input shaft detector captures high-resolution position information that compensates for the low resolution of the output shaft detector, while the output shaft detector provides the actual output position. This segmentation allows achieving high overall resolution without using a single high-resolution detector, thus reducing cost and size.
Solution Approach 2:
The input shaft absolute position detector acts as an intermediary that provides additional position information to compensate for the low resolution of the output shaft detector. By combining the readings from both detectors through a relational expression, the system achieves high-resolution output shaft position measurement without requiring the output shaft detector itself to be high-resolution, thereby reducing actuator cost and size.
2Ease of manufacture
If a low-resolution absolute position detector is used on the output shaft, then the cost and size of the actuator are reduced, but the accuracy of the initial position decreases
Solution Approach 1:
The position detection function is segmented between two low-resolution detectors: one on the input shaft and one on the output shaft. The input shaft detector captures high-resolution position information that compensates for the low resolution of the output shaft detector, while the output shaft detector provides the actual output position. This segmentation allows achieving high overall resolution without using a single high-resolution detector, thus reducing cost and size.
Solution Approach 2:
The system changes the parameters of the detection system by using two low-resolution detectors instead of one high-resolution detector. By introducing the input shaft detector with high resolution and combining its readings with the output shaft detector through a relational expression, the system achieves high effective resolution while using only low-resolution components, thereby reducing cost while maintaining accuracy.
3Measurement precision
If a multi-revolution absolute position detector is used on the input shaft, then the output shaft absolute position can be derived, but expensive parts are required thus increasing cost
Solution Approach 1:
The patent uses cheap low-resolution absolute position detectors instead of expensive multi-revolution absolute position detectors. Although low-resolution detectors have limitations, the system compensates for their low resolution by combining them with an input shaft detector and using a relational expression to achieve high-resolution output shaft position measurement, thus achieving the desired precision with inexpensive components.
Solution Approach 2:
The position detection function is segmented between two low-resolution detectors: one on the input shaft and one on the output shaft. The input shaft detector captures high-resolution position information that compensates for the low resolution of the output shaft detector, while the output shaft detector provides the actual output position. This segmentation allows achieving high overall resolution without using a single high-resolution detector, thus reducing cost and size.
Data Source
AI summary
Disclosed are a device and a method for controlling a motor. According to a specific embodiment of the present disclosure, an input shaft of a motor is provided with a low-resolution absolute position detector and an output shaft of the motor is provided with a low-resolution absolute position detector having a resolution greater than or equal to a reduction gear ratio. An initial offset and an offset are defined accordingly, and a high-resolution output shaft absolute position is derived from a relational expression, which is defined by an input shaft absolute position received at a predetermined time interval, a derived offset, an output shaft absolute position, and the reduction gear ratio, such that it is possible to easily detect the high-resolution output shaft absolute position by using a low-price absolute position detector without the modification or addition of an actuator.