Motor Control System Estimating Output Shaft Angle via Torsion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional motor control systems require an output shaft rotational angle sensor for accurate position control, leading to increased system size and cost, and without this sensor, position control accuracy is compromised due to shaft torsion deviations.
Innovation Solution
A motor control system estimates the output shaft rotational angle using the motor shaft rotational angle, torsion rigidity, and shaft torsion torque, eliminating the need for an output shaft rotational angle sensor and improving accuracy through torsional rigidity determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an output shaft rotational angle sensor is provided to achieve high accuracy position control, then position control accuracy is improved, but system size and manufacturing cost increase
Solution Approach 1:
The patent creates a virtual copy of the output shaft rotational angle sensor by estimating the rotational angle through calculation based on motor shaft rotational angle and shaft torsion characteristics. This estimation model replicates the function of a physical sensor without requiring actual hardware installation on the output shaft, thereby reducing system complexity while maintaining measurement precision
Solution Approach 2:
The patent replaces the mechanical sensing system (physical output shaft rotational angle sensor) with a computational system that uses mathematical modeling. By substituting the mechanical detection approach with electronic calculation based on known system parameters (torsion rigidity, motor shaft angle), the patent eliminates the need for additional mechanical components while achieving the same measurement objective
2Device complexity
If an output shaft rotational angle sensor is not provided to reduce system size, then system complexity is reduced, but position control accuracy deteriorates due to shaft torsion deviations
Solution Approach 1:
The patent introduces shaft torsion torque and torsion rigidity as intermediary parameters that mediate between the motor shaft rotational angle and the output shaft rotational angle. These intermediaries allow the system to calculate the actual output shaft position by compensating for torsion effects, bridging the gap between motor shaft measurement and output shaft position without requiring direct sensing
Solution Approach 2:
The patent implements a feedback mechanism where the estimated output shaft rotational angle is continuously calculated and used for position control. By feeding back the calculated position information (derived from motor shaft angle plus torsion compensation) into the control system, the patent achieves accurate position control without needing a physical sensor on the output shaft
3Device complexity
If shaft torsion is not compensated to simplify the control system, then device complexity is reduced, but measurement precision deteriorates due to rotational angle deviation
Solution Approach 1:
The patent changes the parameters used for position calculation by incorporating shaft torsion torque and torsion rigidity into the rotational angle estimation formula. Instead of using only the motor shaft rotational angle, the system transforms the calculation to include torsion compensation parameters, thereby improving rotational angle accuracy while maintaining relatively simple control logic through mathematical adjustment
Data Source
Figure 1~2
Figure 3
AI summary
A motor control system includes a motor (MT), a rotational angle sensor (AS) that detects a rotational angle of a motor shaft (θM) of the motor, a torque sensor (TS) that detects shaft torsion torque (τmsr) between the motor shaft, and an output shaft fixed to a load member (LN) driven by the motor, and a motor controller (MC) that controls the motor. The motor controller (MC) estimates a rotational angle of the output shaft (θL), based on the rotational angle of the motor shaft (θM), the shaft torsion torque (τmsr), and torsional rigidity obtained in advance with respect to a region between the motor shaft and the output shaft, and controls the motor, using the estimated rotational angle of the output shaft (θL), thus taking into account torsional displacements.