Auto-Tuning

The manual describes how to tune the cascaded position controller using the Auto-tuning feature.

Before conducting any of the tuning activities please check if motor is functional in torque mode and sensor data is transmitted normally. For high-quality motor control tasks, a precise and reliable sensor should be used. Quality of the motor position control may be insufficient with low resolution sensors, especially if a Hall sensor is used.

The current version of the auto-tuning feature allows user to tune a BLDC motor drive. A load can be attached to the motor. However, if the motor position has very strict limits this feature is not recommended, because the motor may make a few full turns.

Concept of Auto-Tuning

Auto-tuning is performed in three steps:

System identification

The first step is to identify physical properties of the object to build a mathematical model of the target system

Position auto-tuning

The second step is to use the model to calculate controller gains that result in a specified position control-loop performance

Velocity auto-tuning

The third step is to tune the velocity loop with Velocity Auto-Tuning for Cyclic Synchronous Velocity mode (CSV)

Goal of Position Auto-tuning

The Position Auto-tuning process calculates the gains for the cascaded controller automatically.

../../../_images/Cascaded_PID4.png

The core of the cascaded controller is linear. However, there are multiple nonlinear additions: saturation, feedforward terms and integrator clamping.

Note

In our experience, the cascaded PID controller structure is one of the most effective for motor control applications. For details see PID Controllers: Theory, Design, and Tuning

Goal of Velocity Auto-tuning

The Velocity Auto-tuning process calculates the gains for the velocity controller automatically.

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