Kurs PID Tuning for a Pick & Place

Proportional Gain (P)

The proportional term produces an output directly proportional to the current error. The farther the system is from the target, the stronger the correction.

When the proportional gain is increased, the system reacts faster and the rise time decreases. However, if the value is too high, it may cause overshoot and oscillations.

Reducing the proportional gain leads to a slower, less responsive reaction. In some cases, the system may never fully reach the target, resulting in a steady-state error.

A good analogy is a spring pulling the system toward its target: the farther it is, the greater the restoring force.

Integral Gain (I)

The integral term accumulates past errors over time. Its goal is to eliminate steady-state error, i.e., when the system remains near the target without ever fully reaching it.

Increasing the integral gain improves long-term accuracy and allows the system to reach the target precisely. However, if the gain is too high, it can cause overshoot, slow response, and a phenomenon called windup—when the output becomes excessively large due to accumulated error.

Reducing the integral gain may leave a steady-state error, but the system becomes more stable and less prone to abrupt corrections.

You can think of this term as a memory: the controller says, “I’ve been off target for too long, I need to push harder.”

Derivative Gain (D)

The derivative term considers the rate at which the error changes. It acts like a brake, slowing the system as it approaches the target by anticipating future error.

Increasing the derivative gain helps reduce overshoot and dampens oscillations, making the system more stable. However, if it’s too high, it can make the response slow or overly sensitive to sensor noise.

Reducing the derivative gain decreases damping, which may lead to instability and increased overshoot.

This term smooths the approach to the target, like gradually braking before coming to a stop.

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