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 performd in two 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 results in specified position control-loop performance.

Goal of Auto-tuning

The tuning process calculates the gains for the cascaded controller automatically.

../../../_images/Cascaded_PID.png

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

Note

According to academic sources, the cascaded PID controller structure is considered to be one of the most effective for motor control applications. See PID Controllers: Theory, Design, and Tuning