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Add feed-forward and slew rate limiting to advanced drive examples (#2301)

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This commit is contained in:
Oblarg
2020-01-23 21:07:38 -05:00
committed by Peter Johnson
parent 1cee5ccb93
commit 0ab81d768f
16 changed files with 192 additions and 67 deletions
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31
wpilibcExamples/src/main/cpp/examples/MecanumBot/cpp/Drivetrain.cpp
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@@ -1,5 +1,5 @@
/*----------------------------------------------------------------------------*/
/* Copyright (c) 2019 FIRST. All Rights Reserved. */
/* Copyright (c) 2019-2020 FIRST. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
@@ -15,19 +15,32 @@ frc::MecanumDriveWheelSpeeds Drivetrain::GetCurrentState() const {
}
void Drivetrain::SetSpeeds(const frc::MecanumDriveWheelSpeeds& wheelSpeeds) {
const auto frontLeftOutput = m_frontLeftPIDController.Calculate(
const auto frontLeftFeedforward =
m_feedforward.Calculate(wheelSpeeds.frontLeft);
const auto frontRightFeedforward =
m_feedforward.Calculate(wheelSpeeds.frontRight);
const auto backLeftFeedforward =
m_feedforward.Calculate(wheelSpeeds.rearLeft);
const auto backRightFeedforward =
m_feedforward.Calculate(wheelSpeeds.rearRight);
const double frontLeftOutput = m_frontLeftPIDController.Calculate(
m_frontLeftEncoder.GetRate(), wheelSpeeds.frontLeft.to<double>());
const auto frontRightOutput = m_frontRightPIDController.Calculate(
const double frontRightOutput = m_frontRightPIDController.Calculate(
m_frontRightEncoder.GetRate(), wheelSpeeds.frontRight.to<double>());
const auto backLeftOutput = m_backLeftPIDController.Calculate(
const double backLeftOutput = m_backLeftPIDController.Calculate(
m_backLeftEncoder.GetRate(), wheelSpeeds.rearLeft.to<double>());
const auto backRightOutput = m_backRightPIDController.Calculate(
const double backRightOutput = m_backRightPIDController.Calculate(
m_backRightEncoder.GetRate(), wheelSpeeds.rearRight.to<double>());
m_frontLeftMotor.Set(frontLeftOutput);
m_frontRightMotor.Set(frontRightOutput);
m_backLeftMotor.Set(backLeftOutput);
m_backRightMotor.Set(backRightOutput);
m_frontLeftMotor.SetVoltage(units::volt_t{frontLeftOutput} +
frontLeftFeedforward);
m_frontRightMotor.SetVoltage(units::volt_t{frontRightOutput} +
frontRightFeedforward);
m_backLeftMotor.SetVoltage(units::volt_t{backLeftOutput} +
backLeftFeedforward);
m_backRightMotor.SetVoltage(units::volt_t{backRightOutput} +
backRightFeedforward);
}
void Drivetrain::Drive(units::meters_per_second_t xSpeed,

22
wpilibcExamples/src/main/cpp/examples/MecanumBot/cpp/Robot.cpp
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@@ -1,10 +1,11 @@
/*----------------------------------------------------------------------------*/
/* Copyright (c) 2019 FIRST. All Rights Reserved. */
/* Copyright (c) 2019-2020 FIRST. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
/*----------------------------------------------------------------------------*/
#include <frc/SlewRateLimiter.h>
#include <frc/TimedRobot.h>
#include <frc/XboxController.h>
@@ -23,23 +24,32 @@ class Robot : public frc::TimedRobot {
frc::XboxController m_controller{0};
Drivetrain m_mecanum;
// Slew rate limiters to make joystick inputs more gentle; 1/3 sec from 0
// to 1.
frc::SlewRateLimiter<units::scalar> m_xspeedLimiter{3 / 1_s};
frc::SlewRateLimiter<units::scalar> m_yspeedLimiter{3 / 1_s};
frc::SlewRateLimiter<units::scalar> m_rotLimiter{3 / 1_s};
void DriveWithJoystick(bool fieldRelative) {
// Get the x speed. We are inverting this because Xbox controllers return
// negative values when we push forward.
const auto xSpeed =
-m_controller.GetY(frc::GenericHID::kLeftHand) * Drivetrain::kMaxSpeed;
const auto xSpeed = -m_xspeedLimiter.Calculate(
m_controller.GetY(frc::GenericHID::kLeftHand)) *
Drivetrain::kMaxSpeed;
// Get the y speed or sideways/strafe speed. We are inverting this because
// we want a positive value when we pull to the left. Xbox controllers
// return positive values when you pull to the right by default.
const auto ySpeed =
-m_controller.GetX(frc::GenericHID::kLeftHand) * Drivetrain::kMaxSpeed;
const auto ySpeed = -m_yspeedLimiter.Calculate(
m_controller.GetX(frc::GenericHID::kLeftHand)) *
Drivetrain::kMaxSpeed;
// Get the rate of angular rotation. We are inverting this because we want a
// positive value when we pull to the left (remember, CCW is positive in
// mathematics). Xbox controllers return positive values when you pull to
// the right by default.
const auto rot = -m_controller.GetX(frc::GenericHID::kRightHand) *
const auto rot = -m_rotLimiter.Calculate(
m_controller.GetX(frc::GenericHID::kRightHand)) *
Drivetrain::kMaxAngularSpeed;
m_mecanum.Drive(xSpeed, ySpeed, rot, fieldRelative);

7
wpilibcExamples/src/main/cpp/examples/MecanumBot/include/Drivetrain.h
View File

@@ -1,5 +1,5 @@
/*----------------------------------------------------------------------------*/
/* Copyright (c) 2019 FIRST. All Rights Reserved. */
/* Copyright (c) 2019-2020 FIRST. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
@@ -11,6 +11,7 @@
#include <frc/Encoder.h>
#include <frc/PWMVictorSPX.h>
#include <frc/controller/PIDController.h>
#include <frc/controller/SimpleMotorFeedforward.h>
#include <frc/geometry/Translation2d.h>
#include <frc/kinematics/MecanumDriveKinematics.h>
#include <frc/kinematics/MecanumDriveOdometry.h>
@@ -72,4 +73,8 @@ class Drivetrain {
m_backRightLocation};
frc::MecanumDriveOdometry m_odometry{m_kinematics, GetAngle()};
// Gains are for example purposes only - must be determined for your own
// robot!
frc::SimpleMotorFeedforward<units::meters> m_feedforward{1_V, 3_V / 1_mps};
};