Drivetrain#

Introduction #

The VEX IQ (2nd generation) Drivetrain uses a built-in gyro sensor to support precise forward, reverse, and turning movements. These blocks allow the robot to move continuously or for set distances, rotate by degrees or to a heading, and respond to changes in its rotational orientation.

The drivetrain category also includes configuration blocks that let you set drive and turn speeds, define stopping behavior, apply timeouts to avoid execution stalls, and manually update the robot’s heading or rotation values. These features provide flexibility when designing autonomous behaviors or real-time adjustments.

A top-down view of a VEX IQ robot within a blue circular diagram showing cardinal directions. The robot is facing upward (0°). The diagram indicates 90° to the right, 180° at the bottom, and 270° to the left. The robot has orange and gray components, with "VEX3" visible on its front panel. Wheels are visible on both sides of the robot.

Below is a list of available blocks:

Actions – Drive or turn the robot for a set distance, angle, or continuously.

drive – Drives the robot continuously forward or in reverse.
drive for – Drives the robot for a set distance.
turn – Turns the robot continuously left or right.
turn for – Turns the robot a specific number of degrees.
turn to heading – Turns the robot to face a specific absolute heading.
turn to rotation – Turns the robot to reach a specific cumulative rotation.
stop driving – Stops all robot movement.

Settings – Configure drivetrain speeds, stopping, timeouts, and rotation values.

set drive velocity – Sets the speed for all drive blocks.
set turn velocity – Sets the speed for all turn blocks.
set drive stopping – Configures the stopping behavior after movement ends.
set drive timeout – Limits how long drive blocks wait to reach their goal.
set drive heading – Manually sets the robot’s gyro heading value.
set drive rotation – Manually sets the robot’s cumulative rotation value.

Values – Read drivetrain motion status, heading, rotation, velocity, and current draw.

drive is done? – Returns a Boolean indicating whether the drivetrain is no longer moving.
drive is moving? – Returns a Boolean indicating whether the drivetrain is currently moving.
drive heading – Returns the drivetrain’s heading angle (0 to 359.99 degrees).
drive rotation – Returns how much the drivetrain has turned since the project started.
drive velocity – Returns the drivetrain’s current velocity in % or rpm.
drive current – Returns the current (in amps) drawn by the drivetrain’s motors.

Actions #

drive #

The drive block moves the drivetrain forward or in reverse using the current drive velocity. This block runs continuously until another Drivetrain block interrupts it or the project stops.

aria-description goes here#

  drive [forward v]

Parameters

Description

direction

The direction in which the robot drives, which can be one of the following:

forward
reverse

Example

aria-description goes here#

  when started :: hat events
  [Drive forward, then stop.]
  drive [forward v]    
  wait (2) seconds
  stop driving

drive for #

The drive for block moves the drivetrain forward or in reverse for a specified distance using the current drive velocity.

aria-description goes here#

  drive [forward v] for (200) [mm v] ▶

Parameters	Description
direction	The direction in which the robot drives, which can be one of the following: forward reverse
distance	The distance the robot drives, as an integer or decimal.
unit	The unit of measurement, which can be one of the following: mm (millimeters) inches
expanding arrow	By default, this is a waiting block, so the drivetrain will finish moving before running the next block. To make the drivetrain start moving and immediately run the next block right away, expand the block to say and don’t wait.

Example

aria-description goes here#

  when started :: hat events
  [Drive backward 500 mm.]
  drive [reverse v] for (500) [mm v] ▶

turn #

The turn block turns the drivetrain continuously left or right using the current turn velocity. The drivetrain will keep turning until another drivetrain block runs or the project stops.

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  turn [right v]

Parameters	Description
direction	The direction in which the robot turns, which can be one of the following: left right

Parameters

Description

direction

The direction in which the robot turns, which can be one of the following:

left
right

Example

aria-description goes here#

  when started :: hat events
  [Turn right, then stop.]
  turn [right v]
  wait (2) seconds    
  stop driving

turn for #

The turn for block turns the drivetrain left or right for a specific number of degrees using the current turn velocity.

aria-description goes here#

  turn [right v] for (90) degrees ▶

Parameters	Description
direction	The direction in which the robot turns, which can be one of the following: left right
angle	The number of degrees the robot turns, as an integer or decimal.
expanding arrow	By default, this is a waiting block, so the drivetrain will finish turning before running the next block. To make the drivetrain start turning and immediately run the next block right away, expand the block to say and don’t wait.

Parameters

Description

direction

The direction in which the robot turns, which can be one of the following:

left
right

angle

The number of degrees the robot turns, as an integer or decimal.

expanding arrow

By default, this is a waiting block, so the drivetrain will finish turning before running the next block. To make the drivetrain start turning and immediately run the next block right away, expand the block to say and don’t wait.

Example

aria-description goes here#

  when started :: hat events
  [Turn left, then turn around to the right.]
  turn [left v] for (90) degrees ▶
  turn [right v] for (180) degrees ▶

turn to heading #

The turn to heading block turns the drivetrain to face a specific heading using the current turn velocity.

aria-description goes here#

  turn to heading (90) degrees ▶

Parameters	Description
heading	The absolute heading the drivetrain will turn to, from -360 to 360 degrees.
expanding arrow	By default, this is a waiting block, so the drivetrain will finish turning before running the next block. To make the drivetrain start turning and immediately run the next block right away, expand the block to say and don’t wait.

Example

aria-description goes here#

  when started :: hat events
  [Turn to face the cardinal directions.]
  turn to heading (90) degrees ▶
  wait (2) seconds
  turn to heading (180) degrees ▶
  wait (2) seconds
  turn to heading (270) degrees ▶
  wait (2) seconds
  turn to heading (0) degrees ▶
  wait (2) seconds

turn to rotation #

The turn to rotation block turns the drivetrain to face a specific rotational value using the current turn velocity.

aria-description goes here#

  turn to rotation (90) degrees ▶

Parameters	Description
rotation	The cumulative rotation value the robot will turn to, as an integer or decimal.
expanding arrow	By default, this is a waiting block, so the drivetrain will finish turning before running the next block. To make the drivetrain start turning and immediately run the next block right away, expand the block to say and don’t wait.

Example

aria-description goes here#

  when started :: hat events
  [Turn left, then spin in a circle clockwise and face right.]
  turn to rotation (-90) degrees ▶
  wait (2) seconds
  turn to rotation (450) degrees ▶

stop driving #

The stop driving block immediately stops all movement of the drivetrain.

aria-description goes here#

  stop driving

Parameters	Description
	This block has no parameters.

Example

aria-description goes here#

  when started :: hat events
  [Drive forward, then stop.]
  drive [forward v]
  wait [4] seconds
  stop driving

Settings #

set drive velocity #

The set drive velocity block sets the default movement speed as a percentage for all subsequent movement blocks in the project.

aria-description goes here#

  set drive velocity to (50) %

Parameters	Description
velocity	Sets the default movement velocity from 0 to 100 as a percent.

Example

  when started :: hat events
  [Drive forward at the default velocity.]
  drive [forward v] for (100) [mm v] ▶
  wait (1) seconds
  [Move slower.]
  set drive velocity to (20) %
  drive [forward v] for (100) [mm v] ▶
  wait (1) seconds
  [Move faster.]
  set drive velocity to (100) %
  drive [forward v] for (100) [mm v] ▶
  wait (1) seconds

set turn velocity #

The set turn velocity block sets the default velocity as a percent for all subsequent turn blocks in the project.

aria-description goes here#

  set turn velocity to (50) %

Parameters	Description
velocity	Sets the default turn velocity from 0 to 100 as a percent.

Example

  when started :: hat events
  [Turn at default velocity.]
  turn [right v] for (100) degrees ▶
  wait (1) seconds
  [Turn slower.]
  set turn velocity to (20) %
  turn [right v] for (100) degrees ▶
  wait (1) seconds
  [Turn faster.]
  set turn velocity to (100) %
  turn [right v] for (100) degrees ▶
  wait (1) seconds

set drive stopping #

The set drive stopping block sets how the drivetrain behaves when drivetrain movement ends.

aria-description goes here#

  set drive stopping to [brake v]

Parameters	Description
stopping behavior	Sets how the drivetrain stops, which can be one of the following: brake – Stops immediately. coast – Slows gradually to a stop. hold – Stops and resists movement using motor feedback.

Parameters

Description

stopping behavior

Sets how the drivetrain stops, which can be one of the following:

brake – Stops immediately.
coast – Slows gradually to a stop.
hold – Stops and resists movement using motor feedback.

Example

When started, sets stopping to coast, drives forward for 2 seconds, then stops.#

  when started :: hat events
  [Drive forward and coast to a stop.]
  set drive velocity to (100) %
  set drive stopping to [coast v]
  drive [forward v]
  wait (2) seconds
  stop driving

set drive timeout #

The set drive timeout block sets a time limit for how long a Drivetrain block will wait to reach its target. If the robot cannot complete the movement within the set time, it will stop automatically and continue with the next block.

Note: The Drivetrain’s time limit is used to prevent Drivetrain blocks that do not reach their target position from stopping the execution of other blocks in the stack.

aria-description goes here#

  set drive timeout to (1) seconds

Parameters	Description
time	The maximum number of seconds a Drivetrain block will run before stopping and moving to the next block.

Example

When started, limits drive time to 1 second and then turns 90 degrees.#

  when started :: hat events
  [Drive forward for 1 second, then turn.]
  set drive timeout to (1) seconds
  drive [forward v] for (25) [inches v] ▶
  turn [right v] for (90) degrees ▶

set drive heading #

The set drive heading block sets the gyro’s current heading to a specified value.

aria-description goes here#

  set drive heading to (0) degrees

Parameters	Description
heading	The heading value, in degrees, to assign to the gyro’s current orientation.

Example

aria-description goes here#

  when started :: hat events
  [Turn to the left.]
  set drive heading to (90) degrees
  turn to heading (0) degrees ▶

set drive rotation #

The set drive rotation block sets the gyro’s current cumulative rotation value.

aria-description goes here#

  set drive rotation to (0) degrees

Parameters	Description
rotation	The cumulative rotation value to assign, in degrees.

Example

aria-description goes here#

  when started :: hat events
  [Spin counterclockwise two times.]
  set drive rotation to (720) degrees
  turn to rotation (0) degrees ▶

Values #

drive is done?#

The drive is done? block returns a Boolean indicating whether the drivetrain is not moving.

True - The drivetrain is not moving.
False - The drivetrain is moving.

    <drive is done?>

Parameters	Description
	This block has no parameters.

Example

    when started :: hat events
    [Start spinning when the drive is complete.]
    drive [forward v] for (200) [mm v] ◀ and don't wait
    forever
    if <drive is done?> then
    turn [right v] for (360) degrees ▶
    break
    else
    set cursor to row (1) column (1) on screen
    print [Still Moving...] on screen ▶
    wait (0.1) seconds
    clear all rows on screen

drive is moving?#

The drive is moving? block returns a Boolean indicating whether the drivetrain is moving.

True - The drivetrain is moving.
False - The drivetrain is not moving.

    <drive is moving?>

Parameters	Description
	This block has no parameters.

Example

    when started :: hat events
    [Print that the robot is moving while it is still driving.]
    drive [forward v] for (200) [mm v] ◀ and don't wait
    while <drive is moving?>
    set cursor to row (1) column (1) on screen
    print [Still Moving...] on screen ▶
    wait (0.1) seconds
    clear all rows on screen
    end
    set cursor to row (1) column (1) on screen
    print [Done!] on screen ▶

drive heading #

The drive heading block returns the drivetrain’s heading angle as a decimal number, in the range 0 to 359.99 degrees.

    (drive heading in degrees)

Parameters	Description
	This block has no parameters.

Example

    when started :: hat events
    [Display the heading after turning.]
    turn [right v] for (450) degrees ▶
    print (drive heading in degrees) on screen ◀ and set cursor to next row

drive rotation #

The drive rotation block returns how much the drivetrain has turned since the project started, in degrees: positive for clockwise, negative for counterclockwise.

    (drive rotation in degrees)

Parameters	Description
	This block has no parameters.

Example

    when started :: hat events
    [Display the rotation after turning.]
    turn [right v] for (450) degrees ▶
    print (drive rotation in degrees) on screen ◀ and set cursor to next row

drive velocity #

The drive velocity block returns the current speed of the drivetrain in a range from -100% to 100% or -127 rpm to 127 rpm.

    (drive velocity in [% v])

Parameters	Description
unit	The unit of measurement, which can be one of the following: % rpm (rotations per minute)

Example

    when started :: hat events
    [Display the velocity as the robot is moving.]
    drive [forward v]
    wait (1) seconds
    print (drive velocity in [% v]) on screen ◀ and set cursor to next row
    stop driving

drive current #

The drive current block returns the amount of electrical current the motor or motor group is drawing in a range from 0.0 to 1.2 amps (amperes).

    (drive current in [amps v])

Parameters	Description
	This block has no parameters.

Example

    when started :: hat events
    [Display the current as the robot is moving.]
    set print precision to [0.01 v] on screen
    drive [forward v]
    wait (1) seconds
    print (drive current in [amps v]) on screen ◀ and set cursor to next row
    stop driving