Pixy Control Helper

Collaboration diagram for Pixy Control Helper:

Functions
int16_t	pixy_PID_Y (int16_t x, int16_t w)
int16_t	pixy_PID_X (int16_t x, int16_t w)

Detailed Description

A collection of helper functions that contain PID Control code used for object tracking.

Function Documentation

int16_t pixy_PID_X	(	int16_t	x,
		int16_t	w
	)

Execute one step of PID regulation for the X-servo.

Parameters

x	desired value (e.g. current x-position of the biggest block)
w	actual value (e.g desired x-position)

Returns

The offset which needs to be added to the X-Servo position

Definition at line 67 of file pixy_control.c.

{
    float e = 0;
    static float esum = 0;
    static float eold = 0;
    float y = 0;

    e = (float)(x - w);                         // calculate the controller offset

    //----PID-control-------------------------------------------------------------------------
    esum = esum + e;                            // add e to the current sum

    y += REG_PID_KP * e;                        // add the proportional part to the output
    y += REG_PID_KI * REG_PID_TA * esum;        // add the integral part to the output
    y += REG_PID_KD * (e - eold) / REG_PID_TA;  // add the differential part to the output
    //----------------------------------------------------------------------------------------

    eold = e;                                   // save the previous value

    return (int16_t)y;
}

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int16_t pixy_PID_Y	(	int16_t	x,
		int16_t	w
	)

Execute one step of PID regulation for the Y-servo.

Parameters

x	desired value (e.g. current y-position of the biggest block)
w	actual value (e.g desired y-position)

Returns

The offset which needs to be added to the Y-Servo position

Definition at line 44 of file pixy_control.c.

{
    float e = 0;
    static float esum = 0;
    static float eold = 0;
    float y = 0;

    e = (float)(x - w);                         // calculate the controller offset

    //----PID-control-------------------------------------------------------------------------
    esum = esum + e;                            // add e to the current sum

    y += REG_PID_KP * e;                        // add the proportional part to the output
    y += REG_PID_KI * REG_PID_TA * esum;        // add the integral part to the output
    y += REG_PID_KD * (e - eold) / REG_PID_TA;  // add the differential part to the output
    //----------------------------------------------------------------------------------------

    eold = e;                                   // save the previous value

    return (int16_t)y;
}

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