Control Device With Activatable Dead Zone And Low-Pass Filter
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Solution Overview
Problem
Existing control systems with dead zones face challenges in maintaining control quality due to offset-dependent target value achievement and difficulty in correcting disturbance variables, as the controlled variable must leave the dead zone to counteract disturbances, leading to increased energy consumption and actuator wear.
Innovation Solution
A control device with a controller dead zone element that can be activated and deactivated based on control deviation thresholds, combined with a low-pass filter and a disturbance variable dead zone element, which generates an auxiliary manipulated variable to quickly counteract disturbances and reduce actuator activity by smoothing noise and small fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a controller dead zone element is connected upstream of the controller to reduce control interventions and energy consumption, then actuator activity and energy consumption are reduced, but control quality deteriorates and disturbance variables become more difficult to correct
Solution Approach 1:
The control system is segmented into two separate dead zone elements: a controller dead zone element (3) upstream of the controller and a disturbance variable dead zone element (11) downstream of the low-pass filter (10). This segmentation allows each dead zone to serve a specific function - the controller dead zone reduces unnecessary actuator activity while the disturbance variable dead zone maintains control quality by allowing disturbance corrections without triggering full controller responses to normal fluctuations.
Solution Approach 2:
A low-pass filter (10) is introduced as an intermediary component between the disturbance variable measurement and the disturbance variable dead zone element (11). The low-pass filter smooths out high-frequency noise and rapid fluctuations in the disturbance variable, allowing the dead zone element to respond only to significant, sustained disturbances. This intermediary enables the system to distinguish between normal noise and genuine disturbances requiring correction.
2Ease of operation
If a controller dead zone element is used to maintain controlled variable within limits, then actuator wear is reduced, but the controlled variable cannot achieve exact target value and must leave dead zone to counteract disturbances
Solution Approach 1:
The control system separates the functions of maintaining the controlled variable within limits and achieving exact target values by using two distinct dead zone elements. The controller dead zone element (3) allows the controlled variable to fluctuate within acceptable limits without actuator activity, reducing wear. The disturbance variable dead zone element (11) enables precise correction when disturbances occur, maintaining target value achievement capability without requiring the controlled variable to continuously leave the dead zone.
3Speed
If disturbance variable is switched to manipulated variable via low-pass filter and disturbance variable dead zone element, then rapid response to disturbances is achieved and actuator activity is reduced, but noise and small fluctuations may cause unnecessary actuator activity
Solution Approach 1:
The low-pass filter (10) performs preliminary action by smoothing the disturbance variable signal before it reaches the disturbance variable dead zone element (11). This pre-processing removes high-frequency noise and small fluctuations, ensuring that only significant, sustained disturbances trigger actuator activity. The preliminary filtering action prevents noise from causing unnecessary actuator responses while maintaining rapid response to genuine disturbances.
Solution Approach 2:
The disturbance variable dead zone element (11) acts as an intermediary between the low-pass filtered disturbance variable and the manipulated variable. It provides a final thresholding function that blocks small fluctuations and noise from reaching the actuator while allowing significant disturbances to pass through for correction. This intermediary layer ensures that only meaningful disturbances trigger actuator activity.
Data Source
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AI summary
The invention relates to a control device (1) for a process (2), which control device is designed to influence the process (2) by means of a manipulated variable (u) in accordance with a control deviation (e) between a setpoint (w) and a controlled variable (y) influenced by a disturbance variable (d), having a controller (4), which produces the manipulated variable (u) from the control deviation (e) fed to the controller, having a controller dead zone element (3), which is arranged before the controller (4) and which can be activated and deactivated by means of a control apparatus (6), the control deviation (e) fed through the controller dead zone element being influenced by a controller dead zone in the active state of the controller dead zone element and not being influenced by the controller dead zone in the inactive state, the controller dead zone element being deactivated when the control deviation (e) exceeds a first threshold value and being reactivated when the control deviation (e) falls below a second threshold value, which is less than the first threshold value, and having an adding element (7), which contains a low-pass filter (10) and preferably a disturbance-variable dead zone element (11) arranged after the low-pass filter and which produces an auxiliary manipulated variable (u*) from the disturbance variable (d) and adds said auxiliary manipulated variable onto the manipulated variable (u).