PID

PID is a way to control motors to a certain position or velocity.

PID Config

To create PID loop, you need to create a PIDConfig object.

To create one you can use the following constructor:

wom::PIDConfig(std::string path, kp_t kp = kp_t{0}, ki_t ki = ki_t{0}, kd_t kd = kd_t{0},
            error_t stableThresh = error_t{-1}, deriv_t stableDerivThresh = deriv_t{-1},
            in_t izone = in_t{-1})

The constructor is contained inside of a struct holding all of the configuration values.

To create a PIDConfig object you can use the following code:

wom::SwerveDriveConfig::pose_angle_conf_t config {
    "/path/to/pid/in/nt/tables",
    kp,
    ki,
    kd
};

Parameters

Type	Name	Description	See Also
std::string	path	The path in the networktables
wom::PIDConfig::kp_t	kp	The proportional gain
wom::PIDConfig::ki_t	ki	The integral gain
wom::PIDConfig::kd_t	kd	The derivative gain
wom::PIDConfig::error_t	stableThresh	The error threshold for the PID loop to be considered stable
wom::PIDConfig::deriv_t	stableDerivThresh	The derivative threshold for the PID loop to be considered stable
in_t	izone	The integral zone

PID Loop

Then you can create a PID loop using the following code:

main.h

class Example {
    public:
        Example();
    private:
        wom::PIDController<IN, OUT> _pid;
};

main.c

Example::Example() : _pid{"path", config}

where IN is the input type and OUT is the output type.

Methods

SetSetpoint

Sets the setpoint of the PID loop.

void SetSetpoint(IN setpoint);

• setpoint is the setpoint of the PID loop (must always be the same type as IN in the constructor)

GetSetpoint

Gets the setpoint of the PID loop.

IN GetSetpoint();

GetError

Gets the error value of the PID loop.

in_t GetError();

SetWrap

Sets the range of the input. If the input is outside of the range, it will wrap around to the other side of the range.

void SetWrap(std::optional<in_t> range)

Example

_pid.SetWrap(0_rad);

Reset

Resets the integral value

void Reset();

Calculate

Calculates the output of the PID loop.

OUT Calculate(IN input, units::second_t dt, out_t feedforward = out_t{0})

• input is the input of the PID loop (must always be the same type as IN in the constructor)
• dt is the time delta
• feedforward is the feedforward value (must always be the same type as OUT in the constructor)

Example

double output = _pid.Calculate(input, dt, feedforward);

IsStable

Checks if the PID loop is stable.

bool IsStable();