Drive Controller Speed Compensation for Load Torque Variations
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Solution Overview
Problem
Existing drive controllers for machine tools and similar systems cannot stabilize speed control performance due to variations in load torque, which affects the object's movement, especially when acceleration changes rapidly.
Innovation Solution
A drive controller that includes a speed comparator, a speed compensator with position-information-based and speed-information-based gain storage, and a current supply unit to adjust the drive unit's operation based on variable gains corresponding to the object's position and speed, ensuring stable speed control by compensating for load torque variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If acceleration of the object rapidly changes to control position, then position control response is improved, but vibration is caused to the object
Solution Approach 1:
The vibration suppression control calculates a correction value based on detected acceleration and subtracts it from the speed command in advance, before the vibration occurs. This preliminary counteraction prevents vibration caused by rapid acceleration changes while maintaining position control responsiveness.
Solution Approach 2:
The system detects acceleration using an acceleration sensor and feeds this information back to calculate a correction value. This feedback mechanism enables real-time vibration suppression by continuously adjusting the speed command based on actual acceleration conditions.
2Device complexity
If a fixed gain is used in speed control, then device complexity is reduced, but speed control performance becomes unstable when load torque varies
Solution Approach 1:
The system uses variable gain that changes dynamically based on the object's position and speed. The gain is adjusted according to the operating conditions to maintain stable speed control performance even when load torque varies, replacing the fixed gain approach with a dynamic adaptation mechanism.
Solution Approach 2:
The control gain parameter is changed based on position and speed information. By storing position-information-based speed gain information and speed-information-based speed gain information, the system adapts the gain parameter to match current operating conditions, ensuring stable control across varying load torque conditions.
3Object-affected harmful factors
If acceleration sensor is added to detect and suppress vibration, then vibration is reduced, but device complexity increases
Solution Approach 1:
The system uses the acceleration sensor not only for vibration detection but also leverages the detected acceleration information for speed control correction. The same sensor serves dual purposes: vibration suppression and speed control, reducing the need for additional sensors and simplifying the overall system structure.
Data Source
AI summary
A drive controller includes a speed compensation unit that performs a speed compensation for an object based on a result of comparison made by a speed comparator that compares a current speed of the drive object with a speed indicated by a speed command. The speed compensation unit includes a position-information-based speed gain setting unit that sets a position-information-based variable gain based on position-information-based speed gain information representing a relationship between a position of the object and position-information-based variable gain that varies depending on a load torque of the motor when the object is present at a predetermined position, and a speed compensation processor that performs a speed compensation based on a result of the comparison in the speed comparator and the position-information-based variable gain set by the position-information-based speed gain setting unit.