Spindle Positioning Device Using Pre-calculated Braking Acceleration
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Solution Overview
Problem
Existing spindle positioning techniques require time to calculate the acceleration command, leading to suboptimal deceleration and increased stopping time due to the need to measure and calculate acceleration when the rotational speed is less than or equal to the base rotational speed, which can result in the spindle speed becoming lower than the optimal switching speed for the shortest positioning time.
Innovation Solution
A spindle positioning device that calculates and applies the maximum braking acceleration and stop control start speed beforehand, allowing immediate initiation of stop control by switching from speed control to position control at a calculated switching speed, ensuring the spindle is decelerated at the maximum achievable acceleration to stop at a desired rotational position without overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the acceleration command is calculated by measuring and computing acceleration when rotational speed is less than or equal to base rotational speed, then the deceleration control can be performed, but the positioning time increases and the spindle speed becomes lower than the optimal switching speed
Solution Approach 1:
The patent pre-calculates the maximum braking acceleration and stores it in memory before the positioning operation begins. This preliminary action eliminates the need for real-time acceleration measurement and calculation during the positioning process, allowing the control system to immediately use the pre-computed value for deceleration control, thereby reducing positioning time while maintaining accurate deceleration control
Solution Approach 2:
The patent replaces the mechanical measurement and calculation process (measuring acceleration when speed ≤ base speed) with a computational substitution (using pre-calculated maximum braking acceleration based on motor torque characteristics and system inertia). This substitution eliminates the time delay associated with real-time measurement and computation during the critical deceleration phase
2Reliability
If the control mode switching is delayed until acceleration calculation is complete, then accurate deceleration control is achieved, but the switching speed becomes lower than optimal for shortest positioning time
Solution Approach 1:
The maximum braking acceleration is calculated in advance based on the spindle motor's torque characteristics and the spindle system's inertia, and stored in memory. This preliminary calculation ensures that when the control mode switching is needed, the accurate deceleration value is already available, maintaining deceleration control accuracy while enabling switching at the optimal speed for shortest positioning time
3Adaptability or versatility
If the spindle is decelerated using calculated acceleration during real-time operation, then adaptive control is achieved, but the positioning speed is reduced due to calculation time requirements
Solution Approach 1:
The patent performs the adaptive deceleration control parameter calculation (maximum braking acceleration) in advance, before the positioning operation begins. By pre-computing the deceleration value based on known motor characteristics and system inertia, the system maintains adaptive control capabilities while eliminating real-time calculation delays, thereby improving positioning speed without sacrificing control adaptability
Data Source
AI summary
An acceleration command calculator calculates an acceleration command “as” based on an output torque Tmb of the spindle motor applied when the rotational speed is less than or equal to a base rotational speed and an inertia Jm+Jl of the overall spindle. A switching speed calculator calculates a control mode switching speed Vs based on the acceleration command “as”. A control mode switching switch switches from a speed control mode to a position control mode when the motor speed Vm becomes less than or equal to the control mode switching speed Vs, to stop the spindle at a desired rotational position. The control mode switching speed Vs may be a value calculated using the following equation: Vs=60×(amax×0.5)1/2, where a maximum acceleration that can be achieved at this time is represented by a max.