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When to Use PID Autotuning

The PID autotuner blocks in金宝app®Control Design™让您在没有参数化工厂模型或初始控制器设计的情况下调整PID控制器。如果您有一个代码生成产品，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要么开环PID自动箱块。这些块执行频率响应估计实验，该估计实验将信号注入工厂并分别使用反馈回路闭合或打开的工厂输出。该块使用产生的估计频率响应来调整工厂的PID增益。

PID自动传递与任何渐近稳定或整合SISO植物，无论是低阶还是高阶，有或没有时间延迟，有或没有直接馈通。它可以调整任何类型的PID控制器。您通过输入块触发调整过程，因此您可以随时调整控制器。

PID自动吞噬物理植物

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:

  • 为您的工厂获得初始PID设计，您可以通过针对物理厂进行调整。

  • 预览工厂响应并在实时调整控制器之前调整PID自动调谐的设置。这样做有助于确保实时调整不会将系统推出所需的工作范围。

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

Closed-Loop vs. Open-Loop PID Autotuning

PID自动调谐工具让您调整：

  • 在闭环配置中，使用您的工厂控制现有PID控制器（Closed-Loop PID Autotuner堵塞）。

  • In an open-loop configuration (开环PID自动箱堵塞）。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PID设计，请从开环自动调整开始，然后切换到闭环自动调节以进行重新定制或改进。如果您的工厂有初始PID设计，请使用闭环调谐，这对您的工厂更安全。使用闭环自动调谐，控制器保留在循环中：

  • 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.

  • 部署算法的内存占用尺寸略小。

Caution

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

  • 请勿使用具有多个集成器的工厂使用开环PID自动调谐。您可以使用多积分器工厂使用闭环PID自动调谐。

要开始使用任一类型的PID自动箱，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.

当估计实验期间工厂存在大扰动时，PID自动避险不起作用。干扰扭曲了植物对扰动信号的反应，产生了差的估计结果。

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