inertial

Introduction

The Inertial Sensor measures the rotation and orientation of the V5 robot. The sensor can report movement along the x, y, and z axes and can be used to determine heading, rotation, and tilt. The sensor can also measure its acceleration along the x, y, and z axes.

To make Inertial commands appear in VEXcode V5, an Inertial Sensor must be configured in the Devices window.

This page uses Inertial1 as the example Inertial Sensor name. If using a smart drivetrain, the example Inertial Sensor name will be DrivetrainInertial. Replace these with your own configured name as needed.

Below is a list of available methods:

Orientation — Read and control heading, rotation, and sensor calibration.

• heading — Returns the current heading.

• rotation — Returns the current rotation.

• setHeading — Sets the Inertial Sensor’s heading to a specified value.

• setRotation — Sets the Inertial Sensor’s rotation value.

• calibrate — Calibrates the Inertial Sensor for stable heading tracking.

• resetHeading — Sets the heading of the Inertial Sensor to 0.

• resetRotation — Sets the rotation of the Inertial Sensor to 0.

• isCalibrating — Returns whether or not the Inertial Sensor is calibrating.

• changed — Registers a callback function for when the Inertial Sensor’s heading changes.

• installed — Checks if the Inertial Sensor is installed.

Motion — Measure acceleration, angular velocity, and tilt.

• acceleration — Returns the linear acceleration along the x, y, or z axis.

• gyroRate — Returns the gyro rate for one axis of the Inertial Sensor.

• orientation — Returns the orientation for one axis of the Inertial Sensor.

• collision — Registers a callback function for when the Inertial Sensor detects a collision.

• setTurnType — Sets the direction that returns positive values for the heading.

• getTurnType — Returns the direction that returns positive values for heading.

Constructor — Manually initialize and configure an Inertial Sensor.

• inertial — Creates an Inertial Sensor.

Orientation

heading

heading returns the current heading of the Inertial Sensor in the specified units as a float.

Usage:

DrivetrainInertial.heading(units)

Parameters	Description
units	The unit used to represent the heading: degrees turns

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Turn, then show the current heading
  Drivetrain.turnFor(right, 450, degrees);
  Brain.Screen.print("%f", DrivetrainInertial.heading(degrees));
}

rotation

rotation returns the current rotation of the Inertial Sensor in the specified units as a float.

Usage:

DrivetrainInertial.rotation(units)

Parameters	Description
units	The unit used to represent the rotation: degrees turns

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Turn, then show the current rotation
  Drivetrain.turnFor(right, 450, degrees);
  Brain.Screen.print("%f", DrivetrainInertial.rotation(degrees));
}

setHeading

setHeading sets the heading of the Inertial Sensor to a specified value.

Usage:

DrivetrainInertial.setHeading(value, units);

Parameters	Description
value	The heading value to set from 0 to 359 as a double.
units	The unit used to represent the heading: degrees turns

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Turn the robot around
  DrivetrainInertial.setHeading(180, degrees);
  Drivetrain.turnToHeading(0, degrees);
}

setRotation

setRotation sets the rotation of the Inertial Sensor to a specified value.

Usage:

DrivetrainInertial.setRotation(value, units);

Parameters	Description
value	The rotation value to set as a double.
units	The unit used to represent the rotation: degrees turns

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Pretend we have already turned 180 degrees
  DrivetrainInertial.setRotation(-180, degrees);
  Drivetrain.turnToRotation(0, degrees);
}

calibrate

calibrate calibrates the Inertial Sensor. Calibration should be done when the Inertial Sensor is not moving. Allow at least 2 seconds for calibration to complete.

Usage:

Inertial1.calibrate();

Parameters	Description
	This method has no parameters.

resetHeading

resetHeading resets the heading of the Inertial Sensor to 0.

Usage:

Inertial1.resetHeading();

Parameters	Description
	This method has no parameters.

resetRotation

resetRotation resets the rotation of the Inertial Sensor to 0.

Usage:

Inertial1.resetRotation();

Parameters	Description
	This method has no parameters.

isCalibrating

isCalibrating checks if the Inertial Sensor is currently calibrating.

• True — The Inertial Sensor is calibrating.

• False — The Inertial Sensor is not calibrating.

Usage:

Inertial1.isCalibrating()

Parameters	Description
	This method has no parameters.

changed

changed registers a callback function that runs when the Inertial Sensor’s heading value changes.

Usage:
DrivetrainInertial.changed(callback);

Parameters	Description
callback	A previously defined function that executes when the heading value changes.

Callback Signature:
void callback();

Arguments	Description
	This callback function has no arguments.

// Called when the inertial sensor's heading value changes
void onHeadingChanged() {
  Brain.Screen.clearScreen();
  Brain.Screen.setCursor(1, 1);
  Brain.Screen.print("Heading: %.2f", DrivetrainInertial.heading());
}

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Register the onHeadingChanged callback
  // Rotate the robot by hand to see the heading change
  DrivetrainInertial.changed(onHeadingChanged);
}

installed

installed checks if the Inertial Sensor is installed.

• true — The Inertial Sensor is installed.

• false — The Inertial Sensor is not installed.

Usage: Inertial1.installed()

Parameters	Description
	This method has no parameters.

Motion

acceleration

acceleration returns the acceleration of the Inertial Sensor along the specified axis as a double.

Usage:

Inertial1.acceleration(axis)

Parameters	Description
axis	The axis to return the acceleration from: xaxis yaxis zaxis

gyroRate

gyroRate returns the gyro rate for one axis of the Inertial Sensor in the specified units as a double.

Usage:

DrivetrainInertial.gyroRate(axis, units)

Parameters	Description
axis	The axis to return the gyro rate from: xaxis yaxis zaxis
units	The unit used to represent the gyro rate: dps — degrees per second rpm — revolutions per minute velocityUnits::pct — %

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();
  // Display the rate of change of rotation while turning in dps
  Drivetrain.turn(right);
  wait(1, seconds);
  
  Brain.Screen.print(DrivetrainInertial.gyroRate(zaxis, dps));

  Drivetrain.stop();
}

orientation

orientation returns the orientation for one axis of the Inertial Sensor in the specified units as a double.

Usage:

DrivetrainInertial.orientation(type, units)

Parameters	Description
type	The axis to return the orientation from: pitch roll yaw
units	The unit used to represent the orientation: degrees turns

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Let the Inertial Sensor calibrate
  wait(2, seconds);

  while (true) {
    Brain.Screen.clearScreen();
    Brain.Screen.setCursor(1,1);
    // Show the Inertial Sensor's orientation value
    // for roll in degrees
    double orient = DrivetrainInertial.orientation(roll, degrees);
    Brain.Screen.print("%f", orient);
    wait(0.1, seconds);
  }
}

collision

collision registers a callback function that runs when the Inertial Sensor detects a sudden acceleration change indicative of a collision.

Usage: DrivetrainInertial.collision(callback);

Parameters	Description
callback	A previously defined callback function that is called automatically when the axis value changes. The function must match the required callback signature. See Callback Functions for more information.

Callback Signature:
void callback(axisType axis, double x, double y, double z);

Arguments	Description
axisType	The axis on which the collision was detected: xaxis yaxis zaxis
x	Acceleration reading on the x-axis at the time of the collision as a double.
y	Acceleration reading on the y-axis at the time of the collision as a double.
z	Acceleration reading on the z-axis at the time of the collision as a double.

void onCollision(axisType axis, double x, double y, double z) {
  Brain.Screen.print("Collision detected!");
}

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Firmly move the robot by hand briefly to simulate
  // a collision and call the onCollision function
  DrivetrainInertial.collision(onCollision);
}

setTurnType

setTurnType sets the direction that returns positive values for the heading.

Usage: Inertial1.setTurnType(direction);

Parameters	Description
direction	The turn direction that will return positive values: left right

getTurnType

getTurnType returns the direction that returns positive values for heading.

• left — The turn type is left.

• right — The turn type is right.

Usage:

Inertial1.getTurnType();

Parameters	Description
	This method has no parameters.

Constructors

inertial

inertial creates an Inertial Sensor.

Usage: inertial(smartport)

Parameters	Description
port	The Smart Port that the AI Vision Sensor is connected to, written as PORTx where x is the number of the port.

// Create a new object "inertial" with the inertial class.
inertial Inertial1 = inertial(PORT1);