pid.h File Reference

Header file for PID control. More...

#include "pathfinding/maze.h"

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Data Structures
struct	pid_params
	Struct for PID parameters. More...
struct	pid_turn_params
	Struct for turn parameters. More...

Macros
#define	PID_BIAS_LEFT_RATIO   1.05f
	Bias for left ratio.
#define	PID_DEGREES_NORMALISE(x)   ((x + 180) % 360 - 180)
	Normalises degrees to be between 0 and 360. More...
#define	PID_ENCODER_CENTER_OFFSET   5
	Number of encoder steps from the center of a cell.
#define	PID_ENCODER_PIN   21
	Encoder pin for PID.
#define	PID_ENCODER_STEP_MOVE   25
	Number of encoder steps to move 1 cell.
#define	PID_ENCODER_STEP_TURN_180_DEG   36
	Number of encoder steps to turn 180 deg.
#define	PID_ENCODER_STEP_TURN_90_DEG   18
	Number of encoder steps to turn 90 deg.
#define	PID_EPSILON   0.01f
	Epsilon for PID. A small value to prevent division by 0.
#define	PID_KD   0.01f
	Gain for derivative term.
#define	PID_KI   0.05f
	Gain for integral term.
#define	PID_KP   0.01f
	Gain for proportional term.
#define	PID_RATIO_TO_BEARING   -0.035f
	Ratio to bearing for PID.

Typedefs
typedef struct pid_params	pid_params_t
	Struct for PID parameters. More...
typedef struct pid_turn_params	pid_turn_params_t
	Struct for turn parameters.

Functions
void	pid_bearing_correction (float target_bearing, float current_bearing, pid_params_t *p_pid_params)
	Updates the motor differential ratio based on the target bearing and current bearing. More...
float	pid_calculate_correction (float current_bearing, float target_bearing, float current_ratio, pid_params_t *p_pid_params)
	Calculates the PID control signal. More...
void	pid_init_error_correction (pid_params_t *p_pid_params)
	Sets defaults for PID parameters. More...
void	pid_init_structs (pid_turn_params_t *p_turn_params)
	Sets up pid struct(s). More...
void	pid_navigate_turn (pid_turn_params_t *p_turn_params, maze_cardinal_direction_t direction)
	Function to turn the car and move in a given direction. More...

Detailed Description

Header file for PID control.

Author

Bryan Seah

Version

0.1

Date

2023-10-29

Copyright

Copyright (c) 2023

Macro Definition Documentation

PID_DEGREES_NORMALISE

#define PID_DEGREES_NORMALISE

(

x

)

((x + 180) % 360 - 180)

Normalises degrees to be between 0 and 360.

Parameters

[in]

x

Degrees to normalise.

Returns

Normalised degrees.

Typedef Documentation

pid_params_t

typedef struct pid_params pid_params_t

Struct for PID parameters.

Function Documentation

pid_bearing_correction()

void pid_bearing_correction	(	float	target_bearing,
		float	current_bearing,
		pid_params_t *	p_pid_params
	)

Updates the motor differential ratio based on the target bearing and current bearing.

Parameters

[in]	target_bearing	Target bearing of the car in degrees.
[out]	current_bearing	Current bearing of the car in degrees.
[in,out]	p_pid_params	Pointer to the PID parameters.

References pid_params::current_bearing, pid_params::current_ratio, pid_params::epsilon, magneto_get_curr_bearing(), motor_update_ratio(), PID_BIAS_LEFT_RATIO, pid_calculate_correction(), and pid_params::ratio_to_bearing.

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pid_calculate_correction()

float pid_calculate_correction	(	float	current_bearing,
		float	target_bearing,
		float	current_ratio,
		pid_params_t *	p_pid_params
	)

Calculates the PID control signal.

Parameters

[in]	current_bearing	Current bearing of the car in degrees.
[in]	target_bearing	Target bearing of the car in degrees.
[in]	current_ratio	Current motor differential ratio.
[in,out]	p_pid_params	Pointer to the PID parameters.

Returns

float Control signal.

References pid_params::integral, pid_params::k_d, pid_params::k_i, pid_params::k_p, PID_DEGREES_NORMALISE, and pid_params::prev_error.

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pid_init_error_correction()

void pid_init_error_correction

(

pid_params_t *

p_pid_params

)

Sets defaults for PID parameters.

Parameters

[out]

p_pid_params

Pointer to the PID parameters.

References pid_params::current_bearing, pid_params::current_ratio, pid_params::epsilon, pid_params::integral, pid_params::k_d, pid_params::k_i, pid_params::k_p, PID_EPSILON, PID_KD, PID_KI, PID_KP, PID_RATIO_TO_BEARING, pid_params::prev_error, pid_params::ratio_to_bearing, and pid_params::setpoint.

pid_init_structs()

void pid_init_structs

(

pid_turn_params_t *

p_turn_params

)

Sets up pid struct(s).

Parameters

[in,out]

p_turn_params

Pointer to the turn parameters.

References pid_turn_params::b_is_centered, pid_turn_params::b_is_moved_cell, pid_turn_params::b_is_turn_complete, pid_turn_params::b_is_turning, pid_turn_params::encoder_step_count, and pid_turn_params::turn_direction.

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pid_navigate_turn()

void pid_navigate_turn	(	pid_turn_params_t *	p_turn_params,
		maze_cardinal_direction_t	direction
	)

Function to turn the car and move in a given direction.

Parameters

[in,out]	p_turn_params	Pointer to the turn parameters.
[in]	direction	Direction to turn.

References pid_turn_params::b_is_centered, pid_turn_params::b_is_moved_cell, pid_turn_params::b_is_turn_complete, pid_turn_params::b_is_turning, pid_turn_params::encoder_step_count, MAZE_EAST, MAZE_SOUTH, MAZE_WEST, motor_move_forward(), motor_turn_left(), motor_turn_right(), PID_ENCODER_CENTER_OFFSET, PID_ENCODER_STEP_MOVE, PID_ENCODER_STEP_TURN_180_DEG, PID_ENCODER_STEP_TURN_90_DEG, and pid_init_structs().

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