Linear Drive Cart Control With Initial Compensation for Overshoot
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed linear drive systems in independent cart systems experience overshoot and settling time issues during deceleration, which reduce throughput in high-throughput applications.
Innovation Solution
A control system that adds a compensation value to the reference signal as the mover approaches the commanded position, automatically tuning the compensation value based on settling error to minimize overshoot and settling time without affecting throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rapid deceleration is applied to achieve maximum throughput, then speed and productivity are improved, but overshoot and settling time increase reducing positioning precision
Solution Approach 1:
The controller applies preliminary action by adding a compensation value to the reference signal before the mover reaches the commanded position. This compensation is calculated based on the difference between the commanded position and actual position, and is applied in advance to prevent overshoot from occurring, thereby eliminating the need for subsequent corrective actions and settling time.
Solution Approach 2:
The controller implements preliminary anti-action by applying a compensation value that counteracts the tendency toward overshoot before it occurs. The compensation is calculated as a function of position error and applied to the reference signal in advance, creating an opposing force that prevents the harmful overshoot effect from manifesting, thus maintaining both high speed and positioning precision.
2Manufacturing precision
If deceleration rate is reduced to eliminate overshoot, then positioning precision is improved, but traversal speed and throughput decrease
Solution Approach 1:
The controller changes parameters by dynamically adjusting the reference signal through addition of a compensation value. Rather than changing the physical deceleration rate or traversal speed parameters, the system modifies the control parameter (reference signal) to achieve both rapid deceleration without overshoot and maintain high throughput, resolving the contradiction through parameter transformation.
Solution Approach 2:
The system replaces the mechanical approach of reducing deceleration rate with a control system approach. Instead of physically slowing down the deceleration mechanism, the controller uses computational compensation (adding a compensation value to the reference signal) to achieve the same effect of eliminating overshoot while maintaining the original mechanical performance characteristics and throughput.
3Manufacturing precision
If settling time is reduced by reducing deceleration rate, then positioning precision is improved, but the time to reach commanded position increases reducing productivity
Solution Approach 1:
The controller applies preliminary action by calculating and applying the compensation value before the mover reaches the commanded position. This eliminates the need for post-arrival settling time, as the compensation prevents overshoot from occurring in the first place. The total time to reach and stabilize at the commanded position is reduced because no corrective oscillations need to occur.
Solution Approach 2:
The system implements self-service by using the position error information already available in the control loop to generate the compensation value. The controller serves itself by utilizing existing measurement data (difference between commanded and actual position) to create the corrective action, eliminating the need for separate sensing or measurement systems and reducing overall system response time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces or eliminates overshoot and settling time, maintaining high throughput by accurately positioning movers in linear drive systems.
Implementation Method 1
The first and second drive members interact with each other to propel the mover along the track
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A controller for a linear drive system includes compensation of a reference signal as the mover approaches a commanded position along a track. The compensation value is added once as the vehicle approaches the commanded position, adjusting the reference signal. This compensation allows the controller to resolve to a zero reference signal at the same time the vehicle reaches the commanded position. The amount of compensation required may be automatically determined for a particular vehicle to reduce or eliminate overshoot as the vehicle approaches a station. Initially, no compensation is provided and the controller monitors settling error as the vehicle approaches a station. The compensation value is then incremented and the controller again monitors settling error as the vehicle approaches a station. The controller compares the new settling error to the prior settling error and adjusts the compensation value accordingly.