Absolute Encoders
YAGSL supports most common FRC absolute encoders. Absolute encoders are required if you are using a brushed motor .
The absolute encoder value will show up in your driver dashboard under swerve/modules/.../Raw Absolute Encoder
and can be used to tune the absoluteEncoderOffset
in module JSON configuration files under most circumstances.
Absolute Encoder Checklist
Swerve Absolute Encoder Wrapper
YAGSL created wrappers over all supported Absolute Encoders to uniformly fetch and set data that is needed for a Swerve Module to operate. This wrapper is called SwerveAbsoluteEncoder
. All SwerveAbsoluteEncoder
's can be fetched via the SwerveModule
configuration object SwerveModuleConfiguration
absolute encoder attribute absoluteEncoder
. The SwerveModule
is able to be fetched by SwerveDrive.getModules()
easily.
YAGSL created wrappers over all supported Motor Controllers to uniformly fetch and set data that is needed for a Swerve Drive to operate. This wrapper is called SwerveMotor
. All SwerveMotor
's can be fetched via the SwerveModule
configuration object SwerveModuleConfiguration
motor definitions angleMotor
and driveMotor
. The SwerveModule
is able to be fetched by SwerveDrive.getModules()
easily.
import com.ctre.phoenix6.hardware.CANcoder;
/**
* Initialize {@link SwerveDrive} with the directory provided.
*
* @param directory Directory of swerve drive config files.
*/
public SwerveSubsystem(File directory)
{
// Angle conversion factor is 360 / (GEAR RATIO * ENCODER RESOLUTION)
// In this case the gear ratio is 12.8 motor revolutions per wheel rotation.
// The encoder resolution per motor revolution is 1 per motor revolution.
double angleConversionFactor = SwerveMath.calculateDegreesPerSteeringRotation(12.8, 1);
// Motor conversion factor is (PI * WHEEL DIAMETER IN METERS) / (GEAR RATIO * ENCODER RESOLUTION).
// In this case the wheel diameter is 4 inches, which must be converted to meters to get meters/second.
// The gear ratio is 6.75 motor revolutions per wheel rotation.
// The encoder resolution per motor revolution is 1 per motor revolution.
double driveConversionFactor = SwerveMath.calculateMetersPerRotation(Units.inchesToMeters(4), 6.75, 1);
// Configure the Telemetry before creating the SwerveDrive to avoid unnecessary objects being created.
SwerveDriveTelemetry.verbosity = TelemetryVerbosity.HIGH;
try
{
swerveDrive = new SwerveParser(directory).createSwerveDrive(maximumSpeed, angleConversionFactor, driveConversionFactor);
} catch (Exception e)
{
throw new RuntimeException(e);
}
swerveDrive.setHeadingCorrection(false); // Heading correction should only be used while controlling the robot via angle.
for(SwerveModule m : swerveDrive.getModules())
{
System.out.println("Module Name: "+m.configuration.name);
absoluteEncoder = ()m.configuration.absoluteEncoder.getAbsoluteEncoder();
}
}
Absolute Encoder Configuration
Only CTRE devices currently support the canbus
option, if your device is using the roboRIO canbus
you must use the value of null
or "rio"
for supported CTRE devices. If you are using a CANivore, and the device is on the CANivore bus, the name must match the CANivore name.
If your absolute encoder is attached to your SparkMAX, use the function SwerveDrive.pushOffsetsToEncoders()
for the best performance. This sets the onboard PID sensor to the attached encoder!
Inside any module JSON such as frontleft.json
,frontright.json
,backleft.json
,backright.json
this is what you would see to configure a absolute encoder.
{
"drive": {
"type": ,
"id": ,
"canbus":
},
"angle": {
"type": ,
"id": ,
"canbus":
},
"encoder": {
"type": ,
"id": ,
"canbus":
},
"inverted": {
"drive": ,
"angle":
},
"absoluteEncoderOffset": ,
"absoluteEncoderInverted": ,
"location": {
"front": ,
"left":
}
}
Possible Absolute Encoder Types
Try inverting your steering/angle/azimuth motor if your module keeps spinning around.
None
none
Integrated/Attached (via SparkMAX DutyCycle)
SparkMax Analog (via SparkMAX Analog Pin)
SparkMax Analog (via SparkMAX Analog Pin with 5V power)
Canandmag (via SparkMAX)
Canandmag (via CAN)
Throughbore (via DIO)
Thrifty Absolute Magnetic Encoder (via Analog Input)
MA3 (via Analog Input)
SRX Mag (via PWM)
AM Mag (via PWM)
PWM DutyCycle
dutycycle
Analog Encoder
analog
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