Motor External Force Estimation With Temperature-Corrected Friction
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Solution Overview
Problem
Existing methods for estimating external forces acting on motors, such as those using temperature information alone, struggle to accurately account for variations in friction torque due to Coulomb and viscous friction, leading to deviations in motor control accuracy.
Innovation Solution
An external force estimation device and method that calculates output torque, estimates inertia and friction torque using rotational position information, and performs temperature-based correction on friction torque to improve estimation accuracy by subtracting corrected torque components from the output torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature information is used to calculate torque constant, then motor control can be performed, but friction torque variation due to temperature changes cannot be accurately compensated leading to external force estimation deviation
Solution Approach 1:
The patent applies parameter changes by introducing temperature as a correction parameter for friction torque. The friction torque correction unit adjusts the friction torque value based on detected temperature information, accounting for the fact that friction characteristics change with temperature. This allows the system to adapt friction torque parameters dynamically according to thermal conditions, thereby improving external force estimation accuracy without compromising reliability.
2Device complexity
If friction torque is calculated using only position information, then calculation is simple, but temperature-induced variations in friction torque cause estimation deviation
Solution Approach 1:
The patent applies preliminary action by pre-establishing the relationship between temperature and friction torque correction. The system detects temperature in advance and uses this information to correct friction torque before external force estimation is performed. This preliminary temperature-based correction ensures that friction torque values account for thermal effects beforehand, improving estimation accuracy without significantly increasing calculation complexity.
3Power
If torque constant is calculated based on temperature, then motor output can be estimated, but friction torque variations due to temperature are not adequately compensated
Solution Approach 1:
The patent applies segmentation by separating the torque estimation into distinct components: motor output torque calculation and friction torque correction. The friction torque correction unit independently adjusts the friction torque component based on temperature information, while the motor output torque is calculated separately. This segmentation allows targeted compensation of friction torque variations without affecting the overall motor output estimation accuracy.
Data Source
AI summary
An external force estimation device is configured to estimate an external force acting on a motor. The external force estimation device includes a processor. The processor is configured to: calculate an output torque of the motor by using a value of a current supplied to the motor; estimate an inertia torque of the motor by using rotational position information of the motor; estimate a first friction torque of the motor by using the rotational position information of the motor; perform temperature-based correction for the first friction torque by using temperature information of the motor; and estimate the external force by subtracting the inertia torque and the first friction torque after the temperature-based correction from the output torque.