Rotary Axis Controller Deceleration Strategy
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Solution Overview
Problem
Existing rotary axis controllers in machine tools take a long time to decelerate the spindle to a predetermined speed at a predetermined position, especially when dealing with high-speed rotations exceeding 10000 rpm, due to complex braking distance calculations and inefficient deceleration strategies.
Innovation Solution
A controller that calculates a remaining movement amount and uses pre-stored braking distance data based on the maximum torque characteristic of the motor to determine a speed command, allowing for deceleration at full torque when necessary and constant deceleration when the remaining movement equals the braking distance, thereby reducing deceleration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional deceleration control is used, then the rotary axis can be stopped at a predetermined position, but the deceleration time is excessively long
Solution Approach 1:
The braking distance data is pre-calculated and stored in a lookup table based on the motor's maximum torque characteristics. During deceleration control, the controller directly retrieves the appropriate braking distance from the stored data based on current rotational speed, eliminating the need for real-time complex calculations and enabling immediate application of optimal deceleration parameters
Solution Approach 2:
The controller dynamically adjusts deceleration parameters by selecting different braking distance values from the stored data corresponding to different rotational speed ranges. This allows the system to optimize deceleration behavior for each specific speed condition, achieving both rapid deceleration and precise positioning
2Speed
If maximum torque braking is applied continuously, then deceleration speed increases, but mechanical vibrations are generated
Solution Approach 1:
The controller applies maximum torque braking only in specific rotational speed ranges where it is beneficial, while using reduced torque in other ranges. By dividing the deceleration process into speed-based zones with different torque characteristics, the system achieves rapid deceleration when needed while avoiding vibrations in sensitive speed ranges
Solution Approach 2:
The deceleration control dynamically adjusts the torque application based on real-time rotational speed feedback. The controller continuously monitors the current speed and selects the appropriate braking distance from stored data, creating a dynamic control strategy that adapts to changing operating conditions to minimize vibrations while maintaining deceleration efficiency
Data Source
AI summary
A controller of a rotary axis includes: a storage unit that stores data of a braking distance for each rotation number of the rotary axis and provides a current braking distance S3 corresponding to a current rotation number of the rotary axis; and a deceleration command calculating unit that calculates a speed command V2 of the rotary axis on a basis of the remaining movement amount S2 and the current braking distance S3; in which the deceleration command calculating unit maintains the current rotation number of the rotary axis in a case in which a difference S4 between the remaining movement amount S2 and the current braking distance S3 is equal to or greater than a predetermined value, and starts deceleration of the rotary axis in a case in which the difference S4 is less than the predetermined value.