Servo Position Compensation via Drive Force Estimation
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Solution Overview
Problem
Existing servo control systems struggle to precisely compensate for position command values due to the lack of consideration for disturbances such as frictional forces when using a constant multiplier for torque command values, leading to reduced positional precision, especially when machining conditions change.
Innovation Solution
A servo control system that includes a motor control part with a position command generating part, a force estimating part, and a compensating part, which estimates the drive force acting on the driven member and compensates the position command value based on the table drive torque, accounting for disturbance torques to improve positional precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the torque command value is multiplied by a predetermined constant to compensate the position command value, then the positional precision is improved, but the compensation precision deteriorates when disturbance greatly changes
Solution Approach 1:
The patent transitions from a static compensation method (fixed constant multiplication) to a dynamic compensation method where the compensation amount is continuously updated based on real-time drive force estimation. The compensating part dynamically adjusts the position command value by multiplying the estimated drive force with a compensation coefficient, allowing the system to adapt to changing disturbance conditions while maintaining high positional precision
Solution Approach 2:
The patent implements a feedback mechanism where the drive force acting on the driven member is estimated based on the relationship between motor torque and acceleration/deceleration torque. This estimated drive force is then fed back to the compensating part to continuously adjust the position command value, creating a closed-loop system that maintains compensation precision even when disturbances change
2Device complexity
If the position command value is compensated without considering disturbance, then the control system complexity is reduced, but the manufacturing precision deteriorates
Solution Approach 1:
The patent introduces a drive force estimation mechanism as an intermediary that bridges the gap between motor torque and actual driven member position. By estimating the drive force acting on the driven member through the relationship between motor torque and acceleration/deceleration torque, the system indirectly accounts for disturbance effects without requiring direct disturbance measurement, thus improving machining accuracy while keeping the control system relatively simple
Solution Approach 2:
The system uses its own internal parameters (motor torque, acceleration/deceleration torque) to estimate the drive force and perform position compensation. The compensating part utilizes the relationship between these internal parameters to automatically adjust the position command value, allowing the system to self-correct for disturbance effects without external intervention or complex additional sensors
Data Source
AI summary
A servo control system including a servo motor, a driven member driven, a coupling mechanism coupled with the servo motor and the driven member, and a motor control part controlling the servo motor. The motor control part includes a position command generating part generating a position command value of the driven member, a force estimating part estimating the drive force acting on the driven member, a compensating part compensating the position command value based on the drive force estimated by the force estimating part, and a control signal output part outputting a control signal to the servo motor based on a position command value compensated by the compensating part.