2021 Seminar - 2020 Robot Attempt

Conventions

RobotMap

All constants related to connections of physical/electronic compoenents should be defined in RobotMap class:

public class RobotMap {

    public static final int DRIVE_LEFT_MOTOR1 = 5;
    
    public static final I2C.Port SOME_SENSOR_CONNECTION = I2C.Port.kOnboard;

}

Subsystem Creation

Creating subsystem instances should be done in methods in SystemsFactory. Each system should have a method (called create${SYSTEM NAME}) which creates an instance of that system, passing all dependencies to it.

public class SystemsFactory {
    
    ..........
    
    
    public SomeSystem createSomeSystem() {
        SpeedController controller = new SpeedControllers()
                .add(new WPI_VictorSPX(RobotMap.MOTOR_CONNECTION))
                .build();
        return new SomeSystem(controller);
    }
}

Robot Systems

Drive System

• Tank Drive

• Right

  • 2x Talon SRX

• Left

  • 2x Talon SRX

• Actions to write:

  • operate the drive system using an XBOX controller

Advanced

• Sensors
  • Drive distance measurement
    • 2x Encoder:
      • SRX Encoder
      • Right side = connected to right (1)
      • Left Side = connected to left (5)
      • Wheel diameter = 15.24 CM
  • Drive orientation measurement
    • Pigeon IMU gyro (PigeonIMU)
      • Connected to speed controller (1)
      • Reset = gyro.setFusedHeading(0); gyro.setYaw(0);
      • Get angle = gyro.getFusedHeading();

Feeder System

This system is responsible for feeding the shooter with balls from the Hopper system.

• 1x Victor SPX (WPI_VictorSPX)

  • Constant Speed: 0.35

• Actions to write

  • rotate the motor (feeds the shooter)

Climb System

• 2x Victor SPX (PWMVictorSPX)

  • Constant Speed: 0.7

• Sensors

  • Robot Has Risen
    • Switch (DigitalInput)
    • false = robot is at top. true = robot not at top

• Actions to write

  • rotate the motor until the robot has risen (indicated by the switch)

Intake System

Responsible for collecting balls from the field into the hopper for storage.

• 1x Victor SPX (WPI_VictorSPX)

  • Constant Speed: 0.6

• 1x Piston (DoubleSolenoid)

  • open = unfolded, close = folded

• Actions to write

  • rotate the motor (to collect balls)
  • unfold system
  • fold system

Turret System

Responsible for rotating the shooter, so it can shoot towards different directions.

• 1x Talon SRX

  • Speed limit = 0.4

• Actions to write

  • rotate the motor (to direct the shooter)

Advanced

• Sensors
  • Turret orientation
    • SRX Encoder
    • Connected to speed controller (3)
    • To angle conversion = little gear tooth count / large gear tooth count * 360
    • little gear tooth count = 27
    • large gear tooth count = 110
• Max angle 110 degrees (either side)
• PID for angle motion precision
  • Kp = 0.08
  • Ki = 0
  • Kd = 0.19
  • Sensor = Turret orientation
  • Measurement units = angle

Hopper System

Responsible for storing balls. The motor transfers balls from the intake to the storage. The sensor detects when a ball entered from the intake.

• 1x Talon SRX

  • Constant Speed: 0.95

• Sensors:

  • Ball entered system
    • Color Sensor (ColorSensorV3)
      • Ball entered = getProximity() >= 160

• Actions to write

  • rotate the motor
    • when the sensor indicates that a ball has entered stop the action

Shooter System

Responsible for shooting balls.

• 1x Talon FX (WPI_TalonFX)

  • Minimum Speed: 0.2
  • Speed must be positive

• Actions to write

  • rotate the motor (shoot) at a specific speed.

Advanced

• Sensors
  • Motor rotation speed
    • SRX Encoder
    • Connected to speed controller (10)
    • To RPM conversion = getSelectedSensorVelocity() / 2048.0 * 600
• PID for motor speed percision
  • Kp = 0.0007
  • Ki = 0
  • Kd = 0.00026
  • Output limit = [0, 1]
  • Output Ramp Rate = 0.1
  • Sensor = Motor rotation speed
  • Measurement units = RPM
• Interpolation
  • Convert shooting distance -> rotation speed (RPM)
  • Apache commons PolynomialFunctionLagrangeForm
  • Data Points here

Using Components

SRX/FX Encoder

The Talon SRX (and Talon FX) has a special connection for sensors and can be queried for information about it. One such device is a specialized encoder made specifically for the Talon SRX.

There are two uses for those encoder in this robot, all of which are normal encoder usages:

• to measure velocity of motor rotation
• to measure distance traveled by the robot

There are a couple of interesting constant needed:

• PPR (Pulses Per Revolution) - indicates the precision of the sensor.
  • For Talon SRX -> PPR = 4096.0
  • For Talon FX -> PPR = 2048.0

For Measuring Velocity

WPI_TalonSRX talon = ...

// * 600 -> to per minute
double velocityRpm = talon.getSelectedSensorVelocity() * 600.0 / PPR;

For Measuring Distance Passed

WPI_TalonSRX talon = ...

// get distance
double distanceMeters = talon.getSelectedSensorPosition() / PPR * WHEEL_DIAMETER_METERS * Math.PI;

// the position is accumulative. so we can reset it
talon.setSelectedSensorPosition(0);

Pigeon IMU

A sensor board integrating multiple devices. It has a class for usage, so it's quite simple. In this robot there is a usage of a single axis of gyroscope to track the robot orientation.

The device is connected via a Talon SRX device.

WPI_TalonSRX talon = ...;
PigeonIMU pigeon = new PigeonIMU(talon);

double angle = pigeon.getFusedHeading();

// angle is accumulative, so we can reset it
pigeon.setFusedHeading(0);

Color Sensor

The color sensor is a simple device capable of detecting colors. However, it is also capable of detecting distance to objects. Which is what the robot needs it for.

It is connected via a special connection on the RoboRIO called I2C.

ColorSensorV3 sensor = new ColorSensorV3(I2C.Port.kOnboard);

// higher value = closer
double proximity = sensor.getProximity();

Climb Sensor

DigitalInput sensor = new DigitalInput(RobotMap.CLIMB_THINGY);

boolean detected = !sensor.get();