Introduction: In the field of automatic control, PID controller is a classic control strategy, which is widely used in various industrial and non-industrial processes. As the complexity of the control system increases, PID serial multi-closed-loop control and PID parallel multi-closed-loop control become important methods to solve complex control problems. This article will compare the two control strategies from the perspective of advantages and disadvantages, and discuss their applicability in different application scenarios.
1. PID serial multi-closed-loop control PID serial multi-closed-loop control is a hierarchical control strategy in which multiple PID controllers are connected by cascading. The output of each PID controller is used as the input of the next-level controller, thus forming a multi-level closed-loop control system. The advantages of this control strategy mainly include the following aspects:
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Clear structure, easy to understand and implement: PID serial multi-closed-loop control decomposes complex control problems into multiple simple closed-loop problems, making the system structure clear and easy to understand and implement.
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The control can be optimized step by step: PID serial multi-closed-loop control can gradually optimize the control link according to the control level, so as to better improve the stability and performance of the system.
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Easy to deal with priority issues: PID serial multi-closed-loop control can reasonably allocate the priority of control tasks by adjusting the hierarchical relationship of different closed-loops, so as to meet the needs of the system for different control requirements.
However, PID serial multi-closed-loop control also has some disadvantages:
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Strong coupling between closed loops: Due to the hierarchical structure of PID serial multi-closed-loop control, the coupling between closed loops is strong. If there is a problem with one closed loop, it may affect the performance of the entire system.
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Additional delay may be introduced: Due to the calculation delay of each closed-loop in PID serial multi-closed-loop control, the response speed of the system may be affected to a certain extent.
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Need more computing resources: PID serial multi-closed-loop control needs to calculate and transfer the output of the controller step by step, so more computing resources and controllers are required.
2. PID parallel multi-closed-loop control PID parallel multi-closed-loop control is a control strategy that connects multiple closed-loops in parallel. Each closed-loop has its own PID controller and independently calculates the output. The final controller output is weighted and summed to form the final control system output. The advantages of this control strategy mainly include the following aspects:
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The coupling between the closed loops is small: in the PID parallel multi-closed-loop control, each closed-loop is relatively independent, and the problem of one closed-loop will not affect other closed-loops, and the stability of the system is high.
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Multiple control tasks can be processed at the same time: PID parallel multi-closed-loop control can process multiple control tasks at the same time to meet the needs of the system for different control requirements.
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Closed-loop weights can be adjusted flexibly: PID parallel multi-closed-loop control can adjust the weights of different closed-loops to reasonably allocate the priority of control tasks, so as to flexibly respond to different control requirements.
However, PID parallel multi-closed-loop control also has some disadvantages:
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Relatively complex structure: PID parallel multi-closed-loop control involves parallel calculation and weighted sum calculation of multiple independent closed-loop controllers, so its control system structure is relatively complex.
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Higher requirements for computing resources: PID parallel multi-closed-loop control needs to calculate the output of multiple closed-loops at the same time, and perform weighted sum calculations, so the requirements for computing resources are relatively high.
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Difficult to debug: PID parallel multi-closed-loop control involves multiple independent closed-loop controllers, and requires appropriate weight parameter settings, so debugging is relatively difficult.
Conclusion: In summary, PID serial multi-closed-loop control and PID parallel multi-closed-loop control are effective control strategies, which are suitable for different application scenarios and control requirements. PID serial multi-closed-loop control is suitable for relatively simple control systems, which require clear priority of control tasks; PID parallel multi-closed-loop control is suitable for complex control systems, which need to process multiple control tasks at the same time. In specific applications, it is necessary to select an appropriate control strategy according to the actual situation, and optimize and debug it to achieve the ideal control effect.