ARMS API

Constants

Chassis

Constant	Default	Description
LEFT_MOTORS	1, 2	The port numbers (1-21) of the left motors of the drive. A negative number will run the motor in reverse (clockwise).
RIGHT_MOTORS	-3, -4	The port numbers (1-21) of the right motors of the drive. A negative number will run the motor in reverse (clockwise).
GEARSET	200	The RPM of the drive motors.
DISTANCE_CONSTANT	273	Number of motor encoder ticks per distance unit (typically feet) used in driving functions. Default value corresponds to a medium-sized robot driving 1 foot.
DEGREE_CONSTANT	2.3	Number of motor encoder ticks per degree of rotation used in turning functions. Default value corresponds to a medium-sized robot rotating 1 degree.
ACCEL_STEP	8	Used in slew control; a smaller number refers to more slew
ARC_STEP	2	Used in slew control
IMU_PORT	0	The port number (1-21) of the Internal Measurement Unit (IMU). A value of 0 means no IMU.
ENCODER_PORTS	0, 0, 0	The port numbers (1-8) of the first wire of up to 3 Vex Optical Shafter Encoders. The order of the ports is left encoder, right encoder, middle encoder. A value of 0 means no encoder is connected.
EXPANDER_PORT	0	The port number (1-21) of the vex 3-wire port expander. A value of 0 means no port expander.
JOYSTICK_THRESHOLD	10	The amount (0-100) that the joystick has to move before sending power to the motors.

Odometry

PID

Selection

Constant	Default Value	Description
DEFAULT	1	The auton number of the default auton. Auton numbers start from 1.
HUE	360	The base color of the selection screen as a hue (0-360). Default 360 is pure red.
AUTONS	"Front", "Back", "Do Nothing"	The auton names to be displayed on the selection screen. Up to 10 autons are accepted.

Chassis Functions

setBrakeMode

void setBrakeMode(okapi::AbstractMotor::brakeMode b);

b - The Okapi brake mode (coast = 0, brake = 1, hold = 2, invalid = INT32_MAX)

Sets the brake mode of the drive motors.

setBrakeMode(0); // set drive motors to coast mode

resetAngle

void resetAngle(double angle = 0);

Resets the IMU angle to the target angle in degrees.

reset

void reset();

Resets the motor encoders of the drive motors, so that their current position is considered zero.

position

double position(bool yDirection = false, bool forceEncoder = false);

Returns the position, as averaged between the left and right drive motors.

angle

double angle();

Returns the angle of the chassis in degrees.

difference

double difference();

Returns the difference in position between the left and right sides of the chassis.

limitSpeed

double limitSpeed(double speed, double max);

Reduce an input speed to within the bounds of a given max.

slew

double slew(double speed, double step, double* prev);

Returns a gradually accelerating speed towards the target input. Must be called in a loop. The 'prev' variable must persist between function calls.

settled

bool settled();

Returns false if the robot is driving (i.e. the drive motors are in motion), or true if they are not.

waitUntilSettled

void waitUntilSettled();

Delays the program until the robot is no longer driving (see settled).

moveAsync

void moveAsync(double sp, int max = 100)

sp - The target driving distance (default units of inches, must be manually calibrated, see DISTANCE_CONSTANT)
max - The maximum motor speed during the driving action (scaled from 0-100, default 100)

Performs a driving action asynchronously, meaning that the robot does not wait until settled upon reaching the destination.

driveAsync(24); // drive 24 inches forward
driveAsync(-24, 50); // drive 24 inches backward, topping out at half motor speed

turnAsync

void turnAsync(double sp, int max = 100)

sp - The target turning distance (degrees): positive is counterclockwise
max - The maximum motor speed during the turning action (scaled from 0-100, default 100)

Performs a turning action asynchronously, meaning that the robot does not wait until settled upon reaching the destination.

turnAsync(90); // turn 90 degrees CCW
turnAsync(-90, 50); // turn 90 degrees CW, topping out at half motor speed

turnAbsoluteAsync

void turnAbsoluteAsync(double sp, int max = 100)

sp - The target turning distance (degrees): positive is counterclockwise
max - The maximum motor speed during the turning action (scaled from 0-100, default 100)

Performs a turning action to an absolute angle asynchronously, meaning that the robot does not wait until settled upon reaching the destination. The angle is retrieved from the IMU.

holoAsync

void holoAsync(double distance, double angle, int max = 100)

distance - The target driving distance (default units of inches). angle - The target angle relative to forward. max - The maximum motor speed during the action (scaled from 0-100, default 100)

Performs a holonomic movement. This is the equivalent to moveAsync but by changing the angle parameter, the robot can move at odd angles and perform strafing movements.

move

void move(double sp, int max = 100)

sp - The target driving distance (default units of inches)
max - The maximum motor speed during the driving action (scaled from 0-100, default 100)

Performs a driving action and waits until the robot is settled (see waitUntilSettled) upon reaching the destination.

drive(24); // drive 24 inches forward
drive(-24, 50); // drive 24 inches backward, topping out at half motor speed

turn

void turn(double sp, int max = 100)

sp - The target turning distance (degrees): positive is counterclockwise
max - The maximum motor speed during the turning action (scaled from 0-100, default 100)

Performs a turning action and waits until the robot is settled (see waitUntilSettled) upon reaching the destination.

turn(90); // turn 90 degrees CCW
turn(-90, 50); // turn 90 degrees CW, topping out at half motor speed

turnAbsolute

void turn(double sp, int max = 100)

sp - The target turning distance (degrees): positive is counterclockwise
max - The maximum motor speed during the turning action (scaled from 0-100, default 100)

Performs a turning action to an absolute angle and waits until the robot is settled (see waitUntilSettled) upon reaching the destination. The angle is retrieved from the IMU.

turn(90); // turn 90 degrees CCW
turn(-90, 50); // turn 90 degrees CW, topping out at half motor speed

fast

void fast(double sp, int max = 100)

sp - The target driving distance (default units of inches)
max - The maximum motor speed during the driving action (scaled from 0-100, default 100)

Performs a driving action with no PID or waiting until settled. That is, the drive motors are immediately set to max in the designated direction.
Useful for wall alignment or other forced moves.

voltage

void voltage(int t, int left_speed = 100, int right_speed = 0);

t - The duration of the drive action (ms)
left_speed - The left motor speed during the driving action (scaled from 0-100, default 100)
right_speed - The right motor speed during the driving action (scaled from 0-100): if equal to zero, use left motor speed

Drives with no PID (drive motors are immediately set to given values) for a specified duration. Specific motor speeds scaled from 0-100 can also be provided.

timeDrive(1000); // drive forward for 1 second at max speed
timeDrive(2000, 50); // drive forward for 2 seconds at half speed
timeDrive(500, 100, 50); // drive and turn slightly right for 0.5 seconds

velocity

void velocity(int t, int max = 100);

t - The duration of the drive action (ms)
max - The maximum motor speed during the driving action (scaled from 0-100, default 100)

Drives with the motors' BUILT-IN PID Control (see left_drive_vel) in a straight line for a specified duration.

velocity(1000); // drive forward for 1 second at max speed
velocity(2000, 50); // drive forward for 2 seconds at half speed

arcLeft/arcRight

void arcLeft(int length, double rad, int max = 100, int type = 0);
void arcRight(int length, double rad, int max = 100, int type = 0);

length - The desired arc length (degrees)
rad - The radius of the arc (default units of feet)
max - The maximum motor speed during the arc action (scaled from 0-100, default 100)
type - The type of arc (default 0)

Drives in a counterclockwise arc with specified length, radius, and type.
The motivation behind arcMove types is to enable custom curved movement, such that doing arc moves with subsequent types would produce one continuous move:

arcLeft(90, 1, 100, 1) // traces a quarter circle with 1ft radius counterclockwise, STARTING WHILE STATAIONARY AND ENDING AT MAX SPEED
arcRight(45, 1, 100, 2) // traces a 45 degree arc with 1ft radius clockwise, MAINTAINING SPEED AT THE BEGINNING AND END OF THE MOVE
arcLeft(135, 1, 100, 3) //traces a 135 degree arc with 1ft radius counterclockwise, COASTING TO A STOP AT THE END

In total, the 4 types of arc turn are:
0 - Start and end stationary
1 - Start stationary, end in motion
2 - Start and end in motion
3 - Start in motion, end stationary

sLeft/sRight

void sLeft(int arc1, int mid, int arc2, int max = 100);
void sRight(int arc1, int mid, int arc2, int max = 100);

Perform a forward S-shaped movement with a set length and speed.
_sLeft() and _sRight() take the same arguments and perform the same move backwards.

tank

void tank(double left, double right);

Assign a direct motor voltage to each half of the drive. Passing joystick values into this function allows for tank driver operator controls.

arcade

void arcade(double vertical, double horizontal);

Assign a motor voltage to each half of the drive calculated as vertical +/- the horizontal. Passing joystick values into this function allows for arcade driver operator controls.

holonomic

void holonomic(double x, double y, double z);

Assign a motor voltage to each chassis motor individually based on a holonomic calculation. Passing joystick values into this function allows for holonomic driver operator controls.

Odometry Functions

reset

void reset(std::array<double, 2> point = {0, 0});

Reset the current odometry position to the target coordinates.

reset

void reset(std::array<double, 2> point, double angle);

Reset both odometry position and angle.

getAngleError

double getAngleError(std::array<double, 2> point);

Returns the difference in robot robot heading from the target point in degrees.

getDistanceError

double getDistanceError(std::array<double, 2> point);

Returns the distance from the robot's current position to the target point.

moveAsync

void moveAsync(std::array<double, 2> point, double max = 80);

Moves the robot asynchronously towards the target point coordinates at the given maximum speed.

holoAsync

void holoAsync(std::array<double, 2> point, double angle, double max = 80, double turnMax = 50);

Moves the robot asynchronously towards the target point coordinates holonomically at the given maximum speed and maximum rate of turning.

move

void move(std::array<double, 2> point, double max = 80);

Moves the robot towards the target point coordinates at the given maximum speed.

moveThru

void moveThru(std::array<double, 2> point, double max = 80);

Moves towards a target point, but exits as soon as the robot enters a radius within the target point. See EXIT_ERROR

holo

void holo(std::array<double, 2> point, double angle, double max = 80, double turnMax = 50);

Moves the robot towards the target point coordinates holonomically at the given maximum speed and maximum rate of turning.

holoThru

void holoThru(std::array<double, 2> point, double angle, double max = 80, double turnMax = 50);

Moves towards a target point holonomically, but exits as soon as the robot enters a radius within the target point. See EXIT_ERROR

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