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https://github.com/wpilibsuite/allwpilib
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221 lines
8.0 KiB
C++
221 lines
8.0 KiB
C++
/*----------------------------------------------------------------------------*/
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/* Copyright (c) 2008-2018 FIRST. All Rights Reserved. */
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/* Open Source Software - may be modified and shared by FRC teams. The code */
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/* must be accompanied by the FIRST BSD license file in the root directory of */
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/* the project. */
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/*----------------------------------------------------------------------------*/
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#pragma once
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#include <wpi/raw_ostream.h>
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#include "frc/drive/RobotDriveBase.h"
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namespace frc {
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class SpeedController;
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/**
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* A class for driving differential drive/skid-steer drive platforms such as
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* the Kit of Parts drive base, "tank drive", or West Coast Drive.
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*
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* These drive bases typically have drop-center / skid-steer with two or more
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* wheels per side (e.g., 6WD or 8WD). This class takes a SpeedController per
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* side. For four and six motor drivetrains, construct and pass in
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* SpeedControllerGroup instances as follows.
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*
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* Four motor drivetrain:
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* @code{.cpp}
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* class Robot {
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* public:
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* frc::Spark m_frontLeft{1};
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* frc::Spark m_rearLeft{2};
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* frc::SpeedControllerGroup m_left{m_frontLeft, m_rearLeft};
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*
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* frc::Spark m_frontRight{3};
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* frc::Spark m_rearRight{4};
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* frc::SpeedControllerGroup m_right{m_frontRight, m_rearRight};
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*
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* frc::DifferentialDrive m_drive{m_left, m_right};
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* };
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* @endcode
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*
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* Six motor drivetrain:
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* @code{.cpp}
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* class Robot {
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* public:
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* frc::Spark m_frontLeft{1};
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* frc::Spark m_midLeft{2};
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* frc::Spark m_rearLeft{3};
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* frc::SpeedControllerGroup m_left{m_frontLeft, m_midLeft, m_rearLeft};
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*
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* frc::Spark m_frontRight{4};
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* frc::Spark m_midRight{5};
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* frc::Spark m_rearRight{6};
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* frc::SpeedControllerGroup m_right{m_frontRight, m_midRight, m_rearRight};
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*
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* frc::DifferentialDrive m_drive{m_left, m_right};
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* };
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* @endcode
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*
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* A differential drive robot has left and right wheels separated by an
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* arbitrary width.
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*
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* Drive base diagram:
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* <pre>
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* |_______|
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* | | | |
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* | |
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* |_|___|_|
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* | |
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* </pre>
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*
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* Each Drive() function provides different inverse kinematic relations for a
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* differential drive robot. Motor outputs for the right side are negated, so
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* motor direction inversion by the user is usually unnecessary.
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*
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* This library uses the NED axes convention (North-East-Down as external
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* reference in the world frame):
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* http://www.nuclearprojects.com/ins/images/axis_big.png.
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*
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* The positive X axis points ahead, the positive Y axis points to the right,
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* and the positive Z axis points down. Rotations follow the right-hand rule, so
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* clockwise rotation around the Z axis is positive.
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*
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* Inputs smaller then 0.02 will be set to 0, and larger values will be scaled
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* so that the full range is still used. This deadband value can be changed
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* with SetDeadband().
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*
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* <p>RobotDrive porting guide:
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* <br>TankDrive(double, double, bool) is equivalent to
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* RobotDrive#TankDrive(double, double, bool) if a deadband of 0 is used.
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* <br>ArcadeDrive(double, double, bool) is equivalent to
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* RobotDrive#ArcadeDrive(double, double, bool) if a deadband of 0 is used
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* and the the rotation input is inverted eg ArcadeDrive(y, -rotation, false)
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* <br>CurvatureDrive(double, double, bool) is similar in concept to
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* RobotDrive#Drive(double, double) with the addition of a quick turn
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* mode. However, it is not designed to give exactly the same response.
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*/
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class DifferentialDrive : public RobotDriveBase {
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public:
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static constexpr double kDefaultQuickStopThreshold = 0.2;
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static constexpr double kDefaultQuickStopAlpha = 0.1;
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/**
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* Construct a DifferentialDrive.
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*
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* To pass multiple motors per side, use a SpeedControllerGroup. If a motor
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* needs to be inverted, do so before passing it in.
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*/
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DifferentialDrive(SpeedController& leftMotor, SpeedController& rightMotor);
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~DifferentialDrive() override = default;
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DifferentialDrive(DifferentialDrive&&) = default;
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DifferentialDrive& operator=(DifferentialDrive&&) = default;
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/**
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* Arcade drive method for differential drive platform.
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*
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* Note: Some drivers may prefer inverted rotation controls. This can be done
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* by negating the value passed for rotation.
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*
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* @param xSpeed The speed at which the robot should drive along the X
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* axis [-1.0..1.0]. Forward is negative.
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* @param zRotation The rotation rate of the robot around the Z axis
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* [-1.0..1.0]. Clockwise is positive.
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* @param squareInputs If set, decreases the input sensitivity at low speeds.
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*/
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void ArcadeDrive(double xSpeed, double zRotation, bool squareInputs = true);
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/**
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* Curvature drive method for differential drive platform.
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*
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* The rotation argument controls the curvature of the robot's path rather
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* than its rate of heading change. This makes the robot more controllable at
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* high speeds. Also handles the robot's quick turn functionality - "quick
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* turn" overrides constant-curvature turning for turn-in-place maneuvers.
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*
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* @param xSpeed The robot's speed along the X axis [-1.0..1.0]. Forward
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* is positive.
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* @param zRotation The robot's rotation rate around the Z axis [-1.0..1.0].
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* Clockwise is positive.
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* @param isQuickTurn If set, overrides constant-curvature turning for
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* turn-in-place maneuvers.
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*/
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void CurvatureDrive(double xSpeed, double zRotation, bool isQuickTurn);
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/**
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* Tank drive method for differential drive platform.
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*
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* @param leftSpeed The robot left side's speed along the X axis
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* [-1.0..1.0]. Forward is positive.
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* @param rightSpeed The robot right side's speed along the X axis
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* [-1.0..1.0]. Forward is positive.
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* @param squareInputs If set, decreases the input sensitivity at low speeds.
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*/
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void TankDrive(double leftSpeed, double rightSpeed, bool squareInputs = true);
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/**
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* Sets the QuickStop speed threshold in curvature drive.
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*
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* QuickStop compensates for the robot's moment of inertia when stopping after
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* a QuickTurn.
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*
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* While QuickTurn is enabled, the QuickStop accumulator takes on the rotation
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* rate value outputted by the low-pass filter when the robot's speed along
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* the X axis is below the threshold. When QuickTurn is disabled, the
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* accumulator's value is applied against the computed angular power request
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* to slow the robot's rotation.
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*
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* @param threshold X speed below which quick stop accumulator will receive
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* rotation rate values [0..1.0].
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*/
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void SetQuickStopThreshold(double threshold);
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/**
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* Sets the low-pass filter gain for QuickStop in curvature drive.
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*
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* The low-pass filter filters incoming rotation rate commands to smooth out
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* high frequency changes.
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*
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* @param alpha Low-pass filter gain [0.0..2.0]. Smaller values result in
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* slower output changes. Values between 1.0 and 2.0 result in
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* output oscillation. Values below 0.0 and above 2.0 are
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* unstable.
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*/
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void SetQuickStopAlpha(double alpha);
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/**
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* Gets if the power sent to the right side of the drivetrain is multipled by
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* -1.
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*
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* @return true if the right side is inverted
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*/
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bool IsRightSideInverted() const;
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/**
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* Sets if the power sent to the right side of the drivetrain should be
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* multipled by -1.
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*
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* @param rightSideInverted true if right side power should be multipled by -1
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*/
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void SetRightSideInverted(bool rightSideInverted);
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void StopMotor() override;
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void GetDescription(wpi::raw_ostream& desc) const override;
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void InitSendable(SendableBuilder& builder) override;
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private:
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SpeedController& m_leftMotor;
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SpeedController& m_rightMotor;
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double m_quickStopThreshold = kDefaultQuickStopThreshold;
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double m_quickStopAlpha = kDefaultQuickStopAlpha;
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double m_quickStopAccumulator = 0.0;
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double m_rightSideInvertMultiplier = -1.0;
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};
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} // namespace frc
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