Open-Loop Control¶

Open-Loop control typically refers to directly controlling device output.

There are open-loop control requests for all Talon FX® and Talon FXS® control output types. With the exception of FOC-only control requests, all open-loop control requests follow the naming pattern {ControlOutputType}Out. For example, the open-loop Voltage control request is called VoltageOut. FOC-only control requests follow the naming pattern {ControlOutputType}.

In the below example, note that devices are initialized with two arguments. These arguments correspond to the device ID and CAN bus name. For CANivore®, this is the name of the CANivore® as configured in Phoenix Tuner X. For more information, see the CANivore® API documentation.

Java

// initialize devices on the rio can bus
final CANBus kCANBus = CANBus.roboRIO();
final TalonFX m_leftLeader = new TalonFX(0, kCANBus);
final TalonFX m_rightLeader = new TalonFX(1, kCANBus);

// users should reuse control requests when possible
final DutyCycleOut m_leftRequest = new DutyCycleOut(0.0);
final DutyCycleOut m_rightRequest = new DutyCycleOut(0.0);

// retrieve joystick inputs
var forward = -m_driverJoy.getLeftY();
var turn = m_driverJoy.getRightX();

// calculate motor outputs, utilizes a "arcade" style of driving;
// where left Y controls forward and right X controls rotation/turn
var leftOut = forward + turn;
var rightOut = forward - turn;

// set request to motor controller
m_leftLeader.setControl(m_leftRequest.withOutput(leftOut));
m_rightLeader.setControl(m_rightRequest.withOutput(rightOut));

C++

// initialize devices on the rio can bus
static constexpr CANBus kCANBus = CANBus::RoboRIO();
hardware::TalonFX m_leftLeader{0, kCANBus};
hardware::TalonFX m_rightLeader{1, kCANBus};

// users should reuse control requests when possible
controls::DutyCycleOut m_leftRequest{0.0};
controls::DutyCycleOut m_rightRequest{0.0};

// retrieve joystick inputs
auto forward = -m_driverJoy.GetLeftY();
auto turn = m_driverJoy.GetRightX();

// calculate motor outputs, utilizes a "arcade" style of driving;
// where left Y controls forward and right X controls rotation/turn
auto leftOut = forward + turn;
auto rightOut = forward - turn;

// set request to motor controller
m_leftLeader.SetControl(m_leftRequest.WithOutput(leftOut));
m_rightLeader.SetControl(m_rightRequest.WithOutput(rightOut));

Python

# initialize devices on the rio can bus
self.canbus = CANBus.roborio()
self.left_leader = hardware.TalonFX(0, self.canbus)
self.right_leader = hardware.TalonFX(1, self.canbus)

# users should reuse control requests when possible
self.left_request = controls.DutyCycleOut(0.0)
self.right_request = controls.DutyCycleOut(0.0)

# retrieve joystick inputs
forward = -self.driver_joy.getLeftY()
turn = self.driver_joy.getRightX()

# calculate motor outputs, utilizes a "arcade" style of driving
# where left Y controls forward and right X controls rotation/turn
left_out = forward + turn
right_out = forward - turn

# set request to motor controllers
self.left_leader.set_control(self.left_request.with_output(left_out))
self.right_leader.set_control(self.right_request.with_output(right_out))