gistfile1.txt

using System;

public class QuaternionPIDController
{
    // PID gains for each component of the quaternion
    private double Kp;
    private double Ki;
    private double Kd;

    // Integral and derivative terms for each component of the quaternion
    private Quaternion integralError;
    private Quaternion previousError;

    // Desired quaternion setpoint
    private Quaternion setpoint;

    public QuaternionPIDController(double kp, double ki, double kd)
    {
        Kp = kp;
        Ki = ki;
        Kd = kd;

        integralError = new Quaternion(0, 0, 0, 0);
        previousError = new Quaternion(0, 0, 0, 0);
        setpoint = new Quaternion(0, 0, 0, 1);
    }

    public void SetSetpoint(Quaternion desiredSetpoint)
    {
        setpoint = desiredSetpoint;
    }

    public Quaternion Update(Quaternion currentOrientation, double deltaTime)
    {
        // Calculate the error between the current orientation and the setpoint
        Quaternion error = setpoint * Quaternion.Conjugate(currentOrientation);

        // Ensure the error lies within the shortest arc
        if (error.W < 0)
        {
            error = new Quaternion(-error.X, -error.Y, -error.Z, -error.W);
        }

        // Update integral term
        integralError += error * deltaTime;

        // Update derivative term
        Quaternion derivativeError = (error - previousError) / deltaTime;
        previousError = error;

        // Calculate the control output
        Quaternion controlOutput = Kp * error + Ki * integralError + Kd * derivativeError;

        // Return the control output (ensure it's a valid quaternion)
        return Quaternion.Normalize(controlOutput);
    }
}