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When to Use PID Autotuning

The PID autotuner blocks in金宝app®Control Design™让您在没有参数植物模型或初始控制器设计的情况下调整PID控制器。如果您有代码生成产品，例如金宝appSimulink Coder™, you can generate code that implements the tuning algorithm on hardware. Deploying the algorithm to hardware lets you tune a controller for a physical plant, with or without using Simulink to manage the tuning process.

To achieve model-free tuning, use theClosed-Loop PID Autotuner或者开环PID自动调节器块。这些块执行了频率响应估计实验，该实验将信号注入植物并分别封闭或开放，并分别将植物输出测量。这些块使用所得的估计频率响应对植物的调子增益。

PID自动调整可与任何渐近稳定或集成的SISO植物（无论是低阶还是高阶，有或没有时间延迟）以及有或没有直接进料的任何渐近稳定或集成。它可以调整任何类型的PID控制器。您可以通过输入到块触发调整过程，因此您可以随时调整控制器。

PID自动进行物理植物

Embedded PID autotuning is a useful option when you have a PID-controlled system and a test bed or control environment to operate in. In this case, you can deploy an autotuner block to your hardware and automatically tune the gains of the PID controller in your system.

在实践中,您可以管理PID自动调谐process in several ways, including:

PID Autotuning for a Plant Model in金宝app

If you have a plant model in Simulink, you can use PID autotuning to:

  • 获得植物的初始PID设计，您可以通过对物理植物进行调整来完善。

  • 在实时调整控制器之前，预览工厂响应并调整PID自动调整的设置。这样做有助于确保实时调整不会使您的系统进入理想的操作范围。

For more information, seePID Autotuning for a Plant Modeled in Simulink.

Closed-Loop vs. Open-Loop PID Autotuning

PID自动调节工具让您调整：

  • 在闭环配置中，您的工厂受到现有PID控制器的控制（Closed-Loop PID Autotuner堵塞）。

  • In an open-loop configuration (开环PID自动调节器堵塞）。With open-loop autotuning, if the plant is in a feedback loop, the autotuner opens the loop for the duration of the tuning process.

通常，如果您没有初始的PID设计，请从开环自动调整开始，然后切换到闭环自动调整以进行重新调整或改进。如果您对工厂有初始的PID设计，请使用闭环调整，这对于您的植物来说更安全。通过闭环自动调整，控制器将保持在循环中：

  • Reject unexpected plant disturbances to maintain safe operation of the plant during the estimation experiment.

  • Reduce the risk that the perturbations used for the experiment drive the plant away from the desired operating point.

Additional advantages of the closed-loop autotuning approach include:

  • Closed-loop tuning works with multiple-integrator plants. In contrast, you cannot use open-loop autotuning for multiple-integrator plants. Even single-integrator plants risk drifting away from the desired operating point during open-loop tuning.

  • Because the feedback loop remains closed, there is no concern about controller saturation during the tuning process. In contrast, with open-loop autotuning, a controller with integral action can saturate while the loop is open. Such saturation can create a jump at the plant input when the tuning process ends. With open-loop tuning, you must take additional steps to ensure that the controller continues to track autotuner block output during tuning. (See, for instance,PID Autotuning for a Plant Modeled in Simulink）

If safe operation of your plant is not a practical concern (such as when tuning against a plant model in Simulink), open-loop autotuning has these advantages:

  • Open-loop tuning can result in more accurate frequency-response estimation and tuning. In closed-loop tuning, the controller suppresses injected perturbations, which can result in less accurate frequency-response estimation and poorer tuning results.

  • Open-loop tuning is faster. Closed-loop tuning uses a lower-frequency perturbation signal, which makes the process about three times longer.

  • 部署算法的内存足迹略小。

Caution

  • Do not use either closed-loop or open-loop PID autotuning with an unstable plant.

  • 请勿使用具有多个积分器的植物使用开环PID自动调节。您可以使用多积分厂使用闭环PID自动调节。

要开始使用两种类型的PID Autotuner，请参阅How PID Autotuning Works.

When Not to Use PID Autotuning

PID Autotuning is not suitable for unstable plants. The perturbations applied in open-loop tuning can drive an unstable plant to operating conditions that are unsafe for the plant. Although closed-loop autotuning does not have that risk, it does not yield meaningful tuning results for unstable plants.

当估计实验中植物中发生较大干扰时，PID自动调节效果不佳。干扰扭曲了植物对扰动信号的反应，从而产生差异结果。

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