MotionController Class Reference

#include <motion_controller.h>

Inheritance diagram for MotionController:

Classes
struct	m_profile_cfg_t

Public Member Functions
	MotionController (m_profile_cfg_t &config)
	Construct a new Motion Controller object.
void	init (double start_pt, double end_pt) override
	Initialize the motion profile for a new movement This will also reset the PID and profile timers.
double	update (double sensor_val) override
	Update the motion profile with a new sensor value.
double	get () override
void	set_limits (double lower, double upper) override
bool	is_on_target () override
motion_t	get_motion () const

Static Public Member Functions
static FeedForward::ff_config_t	tune_feedforward (TankDrive &drive, OdometryTank &odometry, double pct=0.6, double duration=2)

Detailed Description

Motion Controller class

This class defines a top-level motion profile, which can act as an intermediate between a subsystem class and the motors themselves

This takes the constants kS, kV, kA, kP, kI, kD, max_v and acceleration and wraps around a feedforward, PID and trapezoid profile. It does so with the following formula:

out = feedfoward.calculate(motion_profile.get(time_s)) + pid.get(motion_profile.get(time_s))

For PID and Feedforward specific formulae, see pid.h, feedforward.h, and trapezoid_profile.h

Author

Ryan McGee

Date

7/13/2022

Constructor & Destructor Documentation

MotionController()

MotionController::MotionController

(

m_profile_cfg_t &

config

)

Construct a new Motion Controller object.

Parameters

config

The definition of how the robot is able to move max_v Maximum velocity the movement is capable of accel Acceleration / deceleration of the movement pid_cfg Definitions of kP, kI, and kD ff_cfg Definitions of kS, kV, and kA

Member Function Documentation

get()

double MotionController::get ( )

overridevirtual

Returns

the last saved result from the feedback controller

Implements Feedback.

get_motion()

motion_t MotionController::get_motion

(

)

const

Returns

The current postion, velocity and acceleration setpoints

init()

void MotionController::init ( double start_pt, double end_pt )

overridevirtual

Initialize the motion profile for a new movement This will also reset the PID and profile timers.

Parameters

start_pt	Movement starting position
end_pt	Movement ending posiiton

Implements Feedback.

is_on_target()

bool MotionController::is_on_target ( )

overridevirtual

Returns

Whether or not the movement has finished, and the PID confirms it is on target

Implements Feedback.

set_limits()

void MotionController::set_limits ( double lower, double upper )

overridevirtual

Clamp the upper and lower limits of the output. If both are 0, no limits should be applied. if limits are applied, the controller will not target any value below lower or above upper

Parameters

lower	upper limit
upper	lower limiet

Clamp the upper and lower limits of the output. If both are 0, no limits should be applied.

Parameters

lower	Upper limit
upper	Lower limit

Implements Feedback.

tune_feedforward()

FeedForward::ff_config_t MotionController::tune_feedforward ( TankDrive & drive, OdometryTank & odometry, double pct = 0.6, double duration = 2 )

static

This method attempts to characterize the robot's drivetrain and automatically tune the feedforward. It does this by first calculating the kS (voltage to overcome static friction) by slowly increasing the voltage until it moves.

Next is kV (voltage to sustain a certain velocity), where the robot will record it's steady-state velocity at 'pct' speed.

Finally, kA (voltage needed to accelerate by a certain rate), where the robot will record the entire movement's velocity and acceleration, record a plot of [X=(pct-kV*V-kS), Y=(Acceleration)] along the movement, and since kA*Accel = pct-kV*V-kS, the reciprocal of the linear regression is the kA value.

Parameters

drive	The tankdrive to operate on
odometry	The robot's odometry subsystem
pct	Maximum velocity in percent (0->1.0)
duration	Amount of time the robot should be moving for the test

Returns

A tuned feedforward object

update()

double MotionController::update ( double sensor_val )

overridevirtual

Update the motion profile with a new sensor value.

Parameters

sensor_val

Value from the sensor

Returns

the motor input generated from the motion profile

Implements Feedback.

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The documentation for this class was generated from the following files:

• motion_controller.h
• motion_controller.cpp