frc::LinearSystemId Class Reference

Linear system ID utility functions. More...

#include <frc/system/plant/LinearSystemId.h>

Public Types
template<typename Distance >
using	Velocity_t
template<typename Distance >
using	Acceleration_t

Static Public Member Functions
static constexpr LinearSystem< 2, 1, 2 >	ElevatorSystem (DCMotor motor, units::kilogram_t mass, units::meter_t radius, double gearing)
	Create a state-space model of the elevator system.
static constexpr LinearSystem< 2, 1, 2 >	SingleJointedArmSystem (DCMotor motor, units::kilogram_square_meter_t J, double gearing)
	Create a state-space model of a single-jointed arm system.The states of the system are [angle, angular velocity], inputs are [voltage], and outputs are [angle].
template<typename Distance > requires std::same_as<units::meter, Distance> || std::same_as<units::radian, Distance>
static constexpr LinearSystem< 1, 1, 1 >	IdentifyVelocitySystem (decltype(1_V/Velocity_t< Distance >(1)) kV, decltype(1_V/Acceleration_t< Distance >(1)) kA)
	Create a state-space model for a 1 DOF velocity system from its kV (volts/(unit/sec)) and kA (volts/(unit/sec²)).
template<typename Distance > requires std::same_as<units::meter, Distance> || std::same_as<units::radian, Distance>
static constexpr LinearSystem< 2, 1, 1 >	IdentifyPositionSystem (decltype(1_V/Velocity_t< Distance >(1)) kV, decltype(1_V/Acceleration_t< Distance >(1)) kA)
	Create a state-space model for a 1 DOF position system from its kV (volts/(unit/sec)) and kA (volts/(unit/sec²)).
static constexpr LinearSystem< 2, 2, 2 >	IdentifyDrivetrainSystem (decltype(1_V/1_mps) kVLinear, decltype(1_V/1_mps_sq) kALinear, decltype(1_V/1_mps) kVAngular, decltype(1_V/1_mps_sq) kAAngular)
	Identify a differential drive drivetrain given the drivetrain's kV and kA in both linear {(volts/(meter/sec), (volts/(meter/sec²))} and angular {(volts/(radian/sec), (volts/(radian/sec²))} cases.
static constexpr LinearSystem< 2, 2, 2 >	IdentifyDrivetrainSystem (decltype(1_V/1_mps) kVLinear, decltype(1_V/1_mps_sq) kALinear, decltype(1_V/1_rad_per_s) kVAngular, decltype(1_V/1_rad_per_s_sq) kAAngular, units::meter_t trackwidth)
	Identify a differential drive drivetrain given the drivetrain's kV and kA in both linear {(volts/(meter/sec)), (volts/(meter/sec²))} and angular {(volts/(radian/sec)), (volts/(radian/sec²))} cases.
static constexpr LinearSystem< 1, 1, 1 >	FlywheelSystem (DCMotor motor, units::kilogram_square_meter_t J, double gearing)
	Create a state-space model of a flywheel system, the states of the system are [angular velocity], inputs are [voltage], and outputs are [angular velocity].
static constexpr LinearSystem< 2, 1, 2 >	DCMotorSystem (DCMotor motor, units::kilogram_square_meter_t J, double gearing)
	Create a state-space model of a DC motor system.
template<typename Distance > requires std::same_as<units::meter, Distance> || std::same_as<units::radian, Distance>
static constexpr LinearSystem< 2, 1, 2 >	DCMotorSystem (decltype(1_V/Velocity_t< Distance >(1)) kV, decltype(1_V/Acceleration_t< Distance >(1)) kA)
	Create a state-space model of a DC motor system from its kV (volts/(unit/sec)) and kA (volts/(unit/sec²)).
static constexpr LinearSystem< 2, 2, 2 >	DrivetrainVelocitySystem (const DCMotor &motor, units::kilogram_t mass, units::meter_t r, units::meter_t rb, units::kilogram_square_meter_t J, double gearing)
	Create a state-space model of differential drive drivetrain.

Detailed Description

Linear system ID utility functions.

Member Typedef Documentation

Acceleration_t

template<typename Distance >

using frc::LinearSystemId::Acceleration_t

Initial value:

 units::unit_t<units::compound_unit<
      units::compound_unit<Distance, units::inverse<units::seconds>>,
      units::inverse<units::seconds>>>

Velocity_t

template<typename Distance >

using frc::LinearSystemId::Velocity_t

Initial value:

 units::unit_t<
      units::compound_unit<Distance, units::inverse<units::seconds>>>

Member Function Documentation

DCMotorSystem() [1/2]

static constexpr LinearSystem< 2, 1, 2 > frc::LinearSystemId::DCMotorSystem ( DCMotor motor, units::kilogram_square_meter_t J, double gearing )

inlinestaticconstexpr

Create a state-space model of a DC motor system.

The states of the system are [angular position, angular velocity], inputs are [voltage], and outputs are [angular position, angular velocity].

Parameters

motor	The motor (or gearbox) attached to the system.
J	the moment of inertia J of the DC motor.
gearing	Gear ratio from motor to output.

Throws:

std::domain_error if J <= 0 or gearing <= 0.

See also

https://github.com/wpilibsuite/sysid

DCMotorSystem() [2/2]

template<typename Distance >
requires std::same_as<units::meter, Distance> || std::same_as<units::radian, Distance>

static constexpr LinearSystem< 2, 1, 2 > frc::LinearSystemId::DCMotorSystem ( decltype(1_V/Velocity_t< Distance >(1)) kV, decltype(1_V/Acceleration_t< Distance >(1)) kA )

inlinestaticconstexpr

Create a state-space model of a DC motor system from its kV (volts/(unit/sec)) and kA (volts/(unit/sec²)).

These constants can be found using SysId. the states of the system are [position, velocity], inputs are [voltage], and outputs are [position].

You MUST use an SI unit (i.e. meters or radians) for the Distance template argument. You may still use non-SI units (such as feet or inches) for the actual method arguments; they will automatically be converted to SI internally.

The parameters provided by the user are from this feedforward model:

u = K_v v + K_a a

Parameters

kV	The velocity gain, in volts/(unit/sec).
kA	The acceleration gain, in volts/(unit/sec²).

Throws:

std::domain_error if kV < 0 or kA <= 0.

DrivetrainVelocitySystem()

static constexpr LinearSystem< 2, 2, 2 > frc::LinearSystemId::DrivetrainVelocitySystem ( const DCMotor & motor, units::kilogram_t mass, units::meter_t r, units::meter_t rb, units::kilogram_square_meter_t J, double gearing )

inlinestaticconstexpr

Create a state-space model of differential drive drivetrain.

In this model, the states are [left velocity, right velocity], the inputs are [left voltage, right voltage], and the outputs are [left velocity, right velocity]

Parameters

motor	The motor (or gearbox) driving the drivetrain.
mass	The mass of the robot in kilograms.
r	The radius of the wheels in meters.
rb	The radius of the base (half of the track width), in meters.
J	The moment of inertia of the robot.
gearing	Gear ratio from motor to wheel.

Throws:

std::domain_error if mass <= 0, r <= 0, rb <= 0, J <= 0, or gearing <= 0.

ElevatorSystem()

static constexpr LinearSystem< 2, 1, 2 > frc::LinearSystemId::ElevatorSystem ( DCMotor motor, units::kilogram_t mass, units::meter_t radius, double gearing )

inlinestaticconstexpr

Create a state-space model of the elevator system.

The states of the system are [position, velocity], inputs are [voltage], and outputs are [position].

Parameters

motor	The motor (or gearbox) attached to the carriage.
mass	The mass of the elevator carriage, in kilograms.
radius	The radius of the elevator's driving drum, in meters.
gearing	Gear ratio from motor to carriage.

Throws:

std::domain_error if mass <= 0, radius <= 0, or gearing <= 0.

FlywheelSystem()

static constexpr LinearSystem< 1, 1, 1 > frc::LinearSystemId::FlywheelSystem ( DCMotor motor, units::kilogram_square_meter_t J, double gearing )

inlinestaticconstexpr

Create a state-space model of a flywheel system, the states of the system are [angular velocity], inputs are [voltage], and outputs are [angular velocity].

Parameters

motor	The motor (or gearbox) attached to the flywheel.
J	The moment of inertia J of the flywheel.
gearing	Gear ratio from motor to flywheel.

Throws:

std::domain_error if J <= 0 or gearing <= 0.

IdentifyDrivetrainSystem() [1/2]

static constexpr LinearSystem< 2, 2, 2 > frc::LinearSystemId::IdentifyDrivetrainSystem ( decltype(1_V/1_mps) kVLinear, decltype(1_V/1_mps_sq) kALinear, decltype(1_V/1_mps) kVAngular, decltype(1_V/1_mps_sq) kAAngular )

inlinestaticconstexpr

Identify a differential drive drivetrain given the drivetrain's kV and kA in both linear {(volts/(meter/sec), (volts/(meter/sec²))} and angular {(volts/(radian/sec), (volts/(radian/sec²))} cases.

These constants can be found using SysId.

States: [[left velocity], [right velocity]]
Inputs: [[left voltage], [right voltage]]
Outputs: [[left velocity], [right velocity]]

Parameters

kVLinear	The linear velocity gain in volts per (meters per second).
kALinear	The linear acceleration gain in volts per (meters per second squared).
kVAngular	The angular velocity gain in volts per (meters per second).
kAAngular	The angular acceleration gain in volts per (meters per second squared).

Throws:

domain_error if kVLinear <= 0, kALinear <= 0, kVAngular <= 0, or kAAngular <= 0.

See also

https://github.com/wpilibsuite/sysid

IdentifyDrivetrainSystem() [2/2]

static constexpr LinearSystem< 2, 2, 2 > frc::LinearSystemId::IdentifyDrivetrainSystem ( decltype(1_V/1_mps) kVLinear, decltype(1_V/1_mps_sq) kALinear, decltype(1_V/1_rad_per_s) kVAngular, decltype(1_V/1_rad_per_s_sq) kAAngular, units::meter_t trackwidth )

inlinestaticconstexpr

Identify a differential drive drivetrain given the drivetrain's kV and kA in both linear {(volts/(meter/sec)), (volts/(meter/sec²))} and angular {(volts/(radian/sec)), (volts/(radian/sec²))} cases.

This can be found using SysId.

States: [[left velocity], [right velocity]]
Inputs: [[left voltage], [right voltage]]
Outputs: [[left velocity], [right velocity]]

Parameters

kVLinear	The linear velocity gain in volts per (meters per second).
kALinear	The linear acceleration gain in volts per (meters per second squared).
kVAngular	The angular velocity gain in volts per (radians per second).
kAAngular	The angular acceleration gain in volts per (radians per second squared).
trackwidth	The distance between the differential drive's left and right wheels, in meters.

Throws:

domain_error if kVLinear <= 0, kALinear <= 0, kVAngular <= 0, kAAngular <= 0, or trackwidth <= 0.

See also

https://github.com/wpilibsuite/sysid

IdentifyPositionSystem()

template<typename Distance >
requires std::same_as<units::meter, Distance> || std::same_as<units::radian, Distance>

static constexpr LinearSystem< 2, 1, 1 > frc::LinearSystemId::IdentifyPositionSystem ( decltype(1_V/Velocity_t< Distance >(1)) kV, decltype(1_V/Acceleration_t< Distance >(1)) kA )

inlinestaticconstexpr

Create a state-space model for a 1 DOF position system from its kV (volts/(unit/sec)) and kA (volts/(unit/sec²)).

These constants can be found using SysId. the states of the system are [position, velocity], inputs are [voltage], and outputs are [position].

You MUST use an SI unit (i.e. meters or radians) for the Distance template argument. You may still use non-SI units (such as feet or inches) for the actual method arguments; they will automatically be converted to SI internally.

The parameters provided by the user are from this feedforward model:

u = K_v v + K_a a

Parameters

kV	The velocity gain, in volts/(unit/sec).
kA	The acceleration gain, in volts/(unit/sec²).

Throws:

std::domain_error if kV < 0 or kA <= 0.

See also

https://github.com/wpilibsuite/sysid

IdentifyVelocitySystem()

template<typename Distance >
requires std::same_as<units::meter, Distance> || std::same_as<units::radian, Distance>

static constexpr LinearSystem< 1, 1, 1 > frc::LinearSystemId::IdentifyVelocitySystem ( decltype(1_V/Velocity_t< Distance >(1)) kV, decltype(1_V/Acceleration_t< Distance >(1)) kA )

inlinestaticconstexpr

Create a state-space model for a 1 DOF velocity system from its kV (volts/(unit/sec)) and kA (volts/(unit/sec²)).

These constants can be found using SysId. The states of the system are [velocity], inputs are [voltage], and outputs are [velocity].

You MUST use an SI unit (i.e. meters or radians) for the Distance template argument. You may still use non-SI units (such as feet or inches) for the actual method arguments; they will automatically be converted to SI internally.

The parameters provided by the user are from this feedforward model:

u = K_v v + K_a a

Parameters

kV	The velocity gain, in volts/(unit/sec).
kA	The acceleration gain, in volts/(unit/sec²).

Throws:

std::domain_error if kV < 0 or kA <= 0.

See also

https://github.com/wpilibsuite/sysid

SingleJointedArmSystem()

static constexpr LinearSystem< 2, 1, 2 > frc::LinearSystemId::SingleJointedArmSystem ( DCMotor motor, units::kilogram_square_meter_t J, double gearing )

inlinestaticconstexpr

Create a state-space model of a single-jointed arm system.The states of the system are [angle, angular velocity], inputs are [voltage], and outputs are [angle].

Parameters

motor	The motor (or gearbox) attached to the arm.
J	The moment of inertia J of the arm.
gearing	Gear ratio from motor to arm.

Throws:

std::domain_error if J <= 0 or gearing <= 0.

---

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

• frc/system/plant/LinearSystemId.h