Improve sim behavior

I forgot that the DCMotorSim objects were modeling the motor shaft rotations, not the output shaft. This caused the CANCoder position to rotate ~26 times faster than they should've, leading to instability.
team20 · Jan 27, 2025 · f3b82d7 · f3b82d7
1 parent 0e6c228
commit f3b82d7
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Showing 2 changed files with 9 additions and 9 deletions.
diff --git a/src/main/java/frc/robot/Constants.java b/src/main/java/frc/robot/Constants.java
@@ -39,11 +39,12 @@ public static final class DriveConstants {
 
 		public static final double kTeleopMaxVoltage = 12;
 		public static final double kTeleopMaxTurnVoltage = 7.2;
-		public static final double kGearRatio = 6.12;
+		public static final double kDriveGearRatio = 6.12;
+		public static final double kSteerGearRatio = 150.0 / 7;
 		public static final double kWheelDiameter = Units.inchesToMeters(4);
 		public static final double kWheelCircumference = Math.PI * kWheelDiameter;
 
-		public static final double kMetersPerMotorRotation = kWheelCircumference / kGearRatio;
+		public static final double kMetersPerMotorRotation = kWheelCircumference / kDriveGearRatio;
 
 		// https://docs.wpilib.org/en/latest/docs/software/basic-programming/coordinate-system.html
 		public static final Translation2d kFrontLeftLocation = new Translation2d(0.381, 0.381);

diff --git a/src/main/java/frc/robot/SwerveModule.java b/src/main/java/frc/robot/SwerveModule.java
@@ -56,9 +56,9 @@ public SwerveModule(int canId, int drivePort, int steerPort) {
 		if (RobotBase.isSimulation()) {
 			m_driveMotorModel = new DCMotorSim(
 					LinearSystemId.createDCMotorSystem(kV / (2 * Math.PI), kA / (2 * Math.PI)),
-					DCMotor.getKrakenX60(1).withReduction(kGearRatio));
+					DCMotor.getKrakenX60(1).withReduction(kDriveGearRatio));
 			m_steerMotorModel = new DCMotorSim(
-					LinearSystemId.createDCMotorSystem(kV / (2 * Math.PI), 0.0001 / (2 * Math.PI)),
+					LinearSystemId.createDCMotorSystem(kV / (2 * Math.PI), kA / (2 * Math.PI)),
 					DCMotor.getKrakenX60(1));
 		} else {
 			m_driveMotorModel = null;
@@ -155,14 +155,13 @@ private void updateSim() {
 			m_driveMotorModel.update(0.02);
 			driveMotorState.setRotorVelocity(m_driveMotorModel.getAngularVelocityRPM() / 60);
 			driveMotorState.setRawRotorPosition(m_driveMotorModel.getAngularPositionRotations());
+
 			var encoderSimState = m_CANCoder.getSimState();
-			// These used to be CAN IDs, but apparently any other value causes complete
-			// destabilization of the swerve sim. Do not touch.
-			m_steerMotorSim.iterate(30, 32, 0.02);
 			m_steerMotorModel.setInputVoltage(m_steerMotorSim.getAppliedOutput() * 12);
 			m_steerMotorModel.update(0.02);
-			encoderSimState.setRawPosition(m_steerMotorModel.getAngularPositionRotations());
-			encoderSimState.setVelocity(m_steerMotorModel.getAngularVelocityRPM());
+			m_steerMotorSim.iterate(m_steerMotorModel.getAngularVelocityRPM(), 12, 0.02);
+			encoderSimState.setRawPosition(m_steerMotorModel.getAngularPositionRotations() / kSteerGearRatio);
+			encoderSimState.setVelocity(m_steerMotorModel.getAngularVelocityRPM() / 60 / kSteerGearRatio);
 		}
 	}
 }