Rotation Shaft Fixed-Position Stop Control
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Solution Overview
Problem
Existing fixed-position stop control systems for rotation shafts in machine tools require longer times to stop at a desired position due to rapid speed changes and mechanical shocks during the transition from speed control to position control, which limits the use of acceleration and deceleration abilities and results in inefficient stopping processes.
Innovation Solution
The proposed fixed-position stop control apparatus optimizes the stopping process by ensuring the acceleration before switching to position control is close to the limit of the rotation shaft's acceleration and deceleration abilities, eliminating the need for a speed instruction upper limit and incorporating a move instruction smoothing mechanism to reduce mechanical shocks, allowing for a more efficient and continuous speed transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a speed instruction upper limit is set to ensure continuity between speed control and position control zones, then mechanical shocks are reduced, but the time required for the rotation shaft to stop increases because the acceleration and deceleration abilities are not fully utilized
Solution Approach 1:
The patent dynamically adjusts the speed instruction curve based on the actual acceleration and deceleration capabilities of the rotation shaft. By making the speed instruction adaptive rather than fixed, the system can fully utilize the shaft's dynamic capabilities while maintaining continuity, thus reducing stopping time without causing mechanical shocks
Solution Approach 2:
The patent changes the parameters of the speed instruction curve (specifically the exponential decay rate) to match the actual acceleration and deceleration characteristics of the rotation shaft. This parameter optimization allows the system to operate at the boundary of the shaft's capabilities, maximizing stopping speed while avoiding excessive mechanical stress
2Object-affected harmful factors
If the predetermined speed VZ is made small to reduce mechanical shocks during transition from speed control to position control, then shock is minimized, but the small zone where speed instruction upper limit is employed is extended, increasing the stopping time
Solution Approach 1:
The patent uses feedback from the actual acceleration and deceleration performance of the rotation shaft to optimize the speed instruction curve. By continuously adjusting the curve parameters based on measured performance, the system finds the optimal balance between minimizing mechanical shock and reducing stopping time, rather than using a conservative fixed speed limit
3Loss of time
If the acceleration immediately before switching to position control is increased to utilize the rotation shaft's acceleration ability, then stopping time is reduced, but mechanical shocks occur during the transition from speed control to position control
Solution Approach 1:
The patent uses a smoothly curved exponential speed instruction profile instead of linear or angular transitions. This curved approach ensures continuous acceleration and eliminates abrupt changes, allowing high acceleration utilization without generating mechanical shocks during the transition from speed control to position control
Data Source
Figure 1
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Figure 3A~3C
AI summary
A fixed-position stop control apparatus (10) includes: a move-instruction generating means (22) for generating a move instruction for each control cycle; a position loop control means (25) for position controlling a rotation shaft (61) for each control cycle according to the move instruction generated by the move-instruction generating means; and a speed loop control means (35) for speed controlling the rotation shaft according to one of a speed instruction generated by a higher level control apparatus (45) and a predetermined speed instruction, thereby switching the speed control of the rotation shaft by the speed loop control means to the position control of the rotation shaft by the position loop control means. In this fixed-position stop control apparatus, the move instruction generated by the move-instruction generating means has acceleration smaller than the acceleration corresponding to the acceleration and deceleration ability of the rotation shaft. With this arrangement, time required for the rotation shaft to stop at a fixed position can be decreased.