pid.cpp File Reference

PID control and motor control helpers for robotic hand fingers. More...

#include "pid.h"

Functions
void	PID_Init (PID_t *pid, float kp, float ki, float kd, float out_min, float out_max)
	Initialize a PID controller structure.
void	InitPIDs ()
	Initialize all PID controllers used by the robotic hand.
void	PID_Reset (PID_t *pid)
	Reset a PID controller's internal state.
float	PID_Step (PID_t *pid, float error, float dt)
	Perform one PID control step.
void	SetPhase (float u, uint32_t motor_phase_pin)
	Set motor direction based on signed control effort.
void	PositionControlFinger (uint32_t enc, uint32_t target, PID_t *pid, int pwm_channel, int phase_pin, float dt)
	Perform PID-based position control for a single finger motor.
bool	HomeFinger (uint32_t enc, uint32_t home_target, int pwm_channel, int phase_pin)
	Home a single finger motor to a reference position.

Detailed Description

PID control and motor control helpers for robotic hand fingers.

This module provides:

• Generic PID initialization, reset, and step functions
• Homing control logic for DC motors with encoders
• Position control using PID with PWM + phase output

Designed for use with FreeRTOS-based embedded systems.

Function Documentation

HomeFinger()

bool HomeFinger	(	uint32_t	enc,
		uint32_t	home_target,
		int	pwm_channel,
		int	phase_pin )

Home a single finger motor to a reference position.

Drives the motor toward a known home encoder value using a proportional controller until the error falls below ::HOMING_THRESHOLD.

Parameters

enc	Current encoder reading.
home_target	Desired home encoder value.
pwm_channel	LEDC PWM channel controlling the motor.
phase_pin	GPIO pin controlling motor direction.

Returns

true if the finger is homed, false otherwise.

InitPIDs()

void InitPIDs

(

)

Initialize all PID controllers used by the robotic hand.

Sets gains and output limits for all fingers and palm.

PID_Init()

void PID_Init	(	PID_t *	pid,
		float	kp,
		float	ki,
		float	kd,
		float	out_min,
		float	out_max )

Initialize a PID controller structure.

Sets controller gains, output limits, and clears internal state.

Parameters

pid	Pointer to PID controller structure.
kp	Proportional gain.
ki	Integral gain.
kd	Derivative gain.
out_min	Minimum allowable output.
out_max	Maximum allowable output.

PID_Reset()

void PID_Reset

(

PID_t *

pid

)

Reset a PID controller's internal state.

Clears the integral accumulator and previous error term.

Parameters

pid	Pointer to PID controller structure.

PID_Step()

float PID_Step	(	PID_t *	pid,
		float	error,
		float	dt )

Perform one PID control step.

Computes the control output using proportional, integral, and derivative terms and applies output clamping.

Parameters

pid	Pointer to PID controller structure.
error	Current control error (setpoint - measurement).
dt	Time step in seconds since last update.

Returns

Saturated control output value.

PositionControlFinger()

void PositionControlFinger	(	uint32_t	enc,
		uint32_t	target,
		PID_t *	pid,
		int	pwm_channel,
		int	phase_pin,
		float	dt )

Perform PID-based position control for a single finger motor.

Computes the control effort using PID, sets motor direction, enforces a minimum PWM threshold, and applies the PWM output.

Parameters

enc	Current encoder reading.
target	Desired encoder target value.
pid	Pointer to PID controller for this finger.
pwm_channel	LEDC PWM channel controlling the motor.
phase_pin	GPIO pin controlling motor direction.
dt	Control loop timestep in seconds.

SetPhase()

void SetPhase	(	float	u,
		uint32_t	motor_phase_pin )

Set motor direction based on signed control effort.

Uses the sign of the control signal to determine the motor rotation direction via the phase pin.

Parameters

u	Signed control output.
motor_phase_pin	GPIO pin controlling motor direction.