NavX API

This is not installed on the Robot by default. For installation instructions, see robotpy-navx install docs.

NavX AHRS Interface

class navx.AHRS(*args, **kwargs)

Bases: Gyro, Sendable

Class providing an “Attitude and Heading Reference System” (AHRS) interface to a navX-sensor

Overloaded function.

1. __init__(self: navx._navx.AHRS, spi_port_id: wpilib._wpilib.SPI.Port) -> None

2. __init__(self: navx._navx.AHRS, i2c_port_id: wpilib._wpilib.I2C.Port) -> None

3. __init__(self: navx._navx.AHRS, serial_port_id: wpilib._wpilib.SerialPort.Port) -> None

4. __init__(self: navx._navx.AHRS, spi_port_id: wpilib._wpilib.SPI.Port, update_rate_hz: int) -> None

5. __init__(self: navx._navx.AHRS, spi_port_id: wpilib._wpilib.SPI.Port, spi_bitrate: int, update_rate_hz: int) -> None

6. __init__(self: navx._navx.AHRS, i2c_port_id: wpilib._wpilib.I2C.Port, update_rate_hz: int) -> None

7. __init__(self: navx._navx.AHRS, serial_port_id: wpilib._wpilib.SerialPort.Port, data_type: navx._navx.AHRS.SerialDataType, update_rate_hz: int) -> None

class BoardAxis(value: int)

Bases: pybind11_object

Enumeration of all board axes

Members:

kBoardAxisX : Board X (left/right) Axis

kBoardAxisY : Board Y (forward/reverse) Axis

kBoardAxisZ : Board Z (up/down) Axis

kBoardAxisX = <BoardAxis.kBoardAxisX: 0>

kBoardAxisY = <BoardAxis.kBoardAxisY: 1>

kBoardAxisZ = <BoardAxis.kBoardAxisZ: 2>

property name

property value

class BoardYawAxis

Bases: pybind11_object

Structure describing the current board orientation w/respect to the IMU axes of measurement.

property board_axis

Identifies one of the board axes.

property up

true if axis is pointing up (with respect to gravity); false if pointing down.

class SerialDataType(value: int)

Bases: pybind11_object

navX-Sensor support Serial Data types

Members:

kProcessedData : (default): 6 and 9-axis processed data

kRawData : unprocessed data from each individual sensor

kProcessedData = <SerialDataType.kProcessedData: 0>

kRawData = <SerialDataType.kRawData: 1>

property name

property value

calibrate() → None

Does nothing

static create_i2c(port: wpilib._wpilib.I2C.Port = <Port.kMXP: 1>, update_rate_hz: int = 60) → navx._navx.AHRS

Constructs the AHRS class using I2C communication, overriding the default update rate with a custom rate which may be from 4 to 100, representing the number of updates per second sent by the sensor.

This constructor should be used if communicating via I2C.

Note

Increasing the update rate may increase the CPU utilization.

Parameters:

port (I2C.Port :param update_rate_hz: Custom Update Rate (Hz)) – I2C Port to use

static create_spi(port: wpilib._wpilib.SPI.Port = <Port.kMXP: 4>, bitrate: int = 500000, update_rate_hz: int = 60) → navx._navx.AHRS

Constructs the AHRS class using SPI communication, overriding the default update rate with a custom rate which may be from 4 to 100, representing the number of updates per second sent by the sensor.

This constructor allows the specification of a custom SPI bitrate, in bits/second.

Note

Increasing the update rate may increase the CPU utilization.

Parameters:

• port (SPI.Port) – SPI Port to use

• spi_bitrate – SPI bitrate (Maximum: 2,000,000)

• update_rate_hz – Custom Update Rate (Hz)

enableBoardlevelYawReset(enable: bool) → None

Enables or disables board-level yaw zero (reset) requests. Board-level yaw resets are processed by the sensor board and the resulting yaw angle may not be available to the client software until at least 2 update cycles have occurred. Board-level yaw resets however do maintain synchronization between the yaw angle and the sensor-generated Quaternion and Fused Heading values.

Conversely, Software-based yaw resets occur instantaneously; however, Software- based yaw resets do not update the yaw angle component of the sensor-generated Quaternion values or the Fused Heading values.

enableLogging(enable: bool) → None

Enables or disables logging (via Console I/O) of AHRS library internal behaviors, including events such as transient communication errors.

getAccelFullScaleRangeG() → int

Returns the sensor full scale range (in G) of the X, Y and X-axis accelerometers.

Returns:

accelerometer full scale range in G.

getActualUpdateRate() → int

Returns the navX-Model device’s currently configured update rate. Note that the update rate that can actually be realized is a value evenly divisible by the navX-Model device’s internal motion processor sample clock (200Hz). Therefore, the rate that is returned may be lower than the requested sample rate.

The actual sample rate is rounded down to the nearest integer that is divisible by the number of Digital Motion Processor clock ticks. For instance, a request for 58 Hertz will result in an actual rate of 66Hz (200 / (200 / 58), using integer math.

Returns:

Returns the current actual update rate in Hz (cycles per second).

getAltitude() → float

Returns the current altitude, based upon calibrated readings from a barometric pressure sensor, and the currently-configured sea-level barometric pressure [navX Aero only]. This value is in units of meters.

Note

This value is only valid sensors including a pressure sensor. To determine whether this value is valid, see isAltitudeValid().

Returns:

Returns current altitude in meters (as long as the sensor includes an installed on-board pressure sensor).

getAngle() → float

Returns the total accumulated yaw angle (Z Axis, in degrees) reported by the sensor.

Note

The angle is continuous, meaning it’s range is beyond 360 degrees. This ensures that algorithms that wouldn’t want to see a discontinuity in the gyro output as it sweeps past 0 on the second time around.

Note that the returned yaw value will be offset by a user-specified offset value this user-specified offset value is set by invoking the zeroYaw() method.

Returns:

The current total accumulated yaw angle (Z axis) of the robot in degrees. This heading is based on integration of the returned rate from the Z-axis (yaw) gyro.

getAngleAdjustment() → float

Returns the currently configured adjustment angle. See setAngleAdjustment() for more details.

If this method returns 0 degrees, no adjustment to the value returned via getAngle() will occur. :returns: adjustment, in degrees (range: -360 to 360)

getBarometricPressure() → float

Returns the current barometric pressure, based upon calibrated readings from the onboard pressure sensor. This value is in units of millibar.

Note

This value is only valid for a navX Aero. To determine whether this value is valid, see isAltitudeValid().

Returns:

Returns current barometric pressure (navX Aero only).

getBoardYawAxis() → navx._navx.AHRS.BoardYawAxis

Returns information regarding which sensor board axis (X,Y or Z) and direction (up/down) is currently configured to report Yaw (Z) angle values. NOTE: If the board firmware supports Omnimount, the board yaw axis/direction are configurable.

For more information on Omnimount, please see:

http://navx-mxp.kauailabs.com/navx-mxp/installation/omnimount/

Returns:

The currently-configured board yaw axis/direction.

getByteCount() → float

Returns the count in bytes of data received from the sensor. This could can be useful for diagnosing connectivity issues.

If the byte count is increasing, but the update count (see getUpdateCount()) is not, this indicates a software misconfiguration.

Returns:

The number of bytes received from the sensor.

getCompassHeading() → float

Returns the current tilt-compensated compass heading value (in degrees, from 0 to 360) reported by the sensor.

Note that this value is sensed by a magnetometer, which can be affected by nearby magnetic fields (e.g., the magnetic fields generated by nearby motors).

Before using this value, ensure that (a) the magnetometer has been calibrated and (b) that a magnetic disturbance is not taking place at the instant when the compass heading was generated. :returns: The current tilt-compensated compass heading, in degrees (0-360).

getDisplacementX() → float

Returns the displacement (in meters) of the X axis since resetDisplacement() was last invoked [Experimental].

Note

This feature is experimental. Displacement measures rely on double-integration of acceleration values from MEMS accelerometers which yield “noisy” values. The resulting displacement are not known to be very accurate, and the amount of error increases quickly as time progresses.

Returns:

Displacement since last reset (in meters).

getDisplacementY() → float

Returns the displacement (in meters) of the Y axis since resetDisplacement() was last invoked [Experimental].

Note

This feature is experimental. Displacement measures rely on double-integration of acceleration values from MEMS accelerometers which yield “noisy” values. The resulting displacement are not known to be very accurate, and the amount of error increases quickly as time progresses.

Returns:

Displacement since last reset (in meters).

getDisplacementZ() → float

Returns the displacement (in meters) of the Z axis since resetDisplacement() was last invoked [Experimental].

Note

This feature is experimental. Displacement measures rely on double-integration of acceleration values from MEMS accelerometers which yield “noisy” values. The resulting displacement are not known to be very accurate, and the amount of error increases quickly as time progresses.

Returns:

Displacement since last reset (in meters).

getFirmwareVersion() → str

Returns the version number of the firmware currently executing on the sensor.

To update the firmware to the latest version, please see:

http://navx-mxp.kauailabs.com/navx-mxp/support/updating-firmware/

Returns:

The firmware version in the format [MajorVersion].[MinorVersion]

getFusedHeading() → float

Returns the “fused” (9-axis) heading.

The 9-axis heading is the fusion of the yaw angle, the tilt-corrected compass heading, and magnetic disturbance detection. Note that the magnetometer calibration procedure is required in order to achieve valid 9-axis headings.

The 9-axis Heading represents the sensor’s best estimate of current heading, based upon the last known valid Compass Angle, and updated by the change in the Yaw Angle since the last known valid Compass Angle. The last known valid Compass Angle is updated whenever a Calibrated Compass Angle is read and the sensor has recently rotated less than the Compass Noise Bandwidth (~2 degrees).

Returns:

Fused Heading in Degrees (range 0-360)

getGyroFullScaleRangeDPS() → int

Returns the sensor full scale range (in degrees per second) of the X, Y and X-axis gyroscopes.

Returns:

gyroscope full scale range in degrees/second.

getLastSensorTimestamp() → int

Returns the sensor timestamp corresponding to the last sample retrieved from the sensor. Note that this sensor timestamp is only provided when the Register-based IO methods (SPI, I2C) are used; sensor timestamps are not provided when Serial-based IO methods (TTL UART, USB) are used.

Returns:

The sensor timestamp (in ms) corresponding to the current AHRS sensor data.

Return type:

int

getPitch() → float

Returns the current pitch value (in degrees, from -180 to 180) reported by the sensor. Pitch is a measure of rotation around the X Axis.

Returns:

The current pitch value in degrees (-180 to 180).

getPressure() → float

Returns the current barometric pressure (in millibar) [navX Aero only].

This value is valid only if a barometric pressure sensor is onboard.

Returns:

Returns the current barometric pressure (in millibar).

getQuaternionW() → float

Returns the imaginary portion (W) of the Orientation Quaternion which fully describes the current sensor orientation with respect to the reference angle defined as the angle at which the yaw was last “zeroed”.

Each quaternion value (W,X,Y,Z) is expressed as a value ranging from -2 to 2. This total range (4) can be associated with a unit circle, since each circle is comprised of 4 PI Radians.

For more information on Quaternions and their use, please see this definition.

Returns:

Returns the imaginary portion (W) of the quaternion.

getQuaternionX() → float

Returns the real portion (X axis) of the Orientation Quaternion which fully describes the current sensor orientation with respect to the reference angle defined as the angle at which the yaw was last “zeroed”.

Each quaternion value (W,X,Y,Z) is expressed as a value ranging from -2 to 2. This total range (4) can be associated with a unit circle, since each circle is comprised of 4 PI Radians.

For more information on Quaternions and their use, please see this definition.

Returns:

Returns the real portion (X) of the quaternion.

getQuaternionY() → float

Returns the real portion (Y axis) of the Orientation Quaternion which fully describes the current sensor orientation with respect to the reference angle defined as the angle at which the yaw was last “zeroed”.

Each quaternion value (W,X,Y,Z) is expressed as a value ranging from -2 to 2. This total range (4) can be associated with a unit circle, since each circle is comprised of 4 PI Radians.

For more information on Quaternions and their use, please see:

https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation

Returns:

Returns the real portion (X) of the quaternion.

getQuaternionZ() → float

Returns the real portion (Z axis) of the Orientation Quaternion which fully describes the current sensor orientation with respect to the reference angle defined as the angle at which the yaw was last “zeroed”.

Each quaternion value (W,X,Y,Z) is expressed as a value ranging from -2 to 2. This total range (4) can be associated with a unit circle, since each circle is comprised of 4 PI Radians.

For more information on Quaternions and their use, please see:

https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation

Returns:

Returns the real portion (X) of the quaternion.

getRate() → float

Return the rate of rotation of the yaw (Z-axis) gyro, in degrees per second.

The rate is based on the most recent reading of the yaw gyro angle.

Returns:

The current rate of change in yaw angle (in degrees per second)

getRawAccelX() → float

Returns the current raw (unprocessed) X-axis acceleration rate (in G).

Note

this value is unprocessed, and should only be accessed by advanced users. This raw value has not had acceleration due to gravity removed from it, and has not been rotated to the world reference frame. Gravity-corrected, world reference frame-corrected X axis acceleration data is accessible via the getWorldLinearAccelX() method.

Returns:

Returns the current acceleration rate (in G).

getRawAccelY() → float

Returns the current raw (unprocessed) Y-axis acceleration rate (in G).

Note

this value is unprocessed, and should only be accessed by advanced users. This raw value has not had acceleration due to gravity removed from it, and has not been rotated to the world reference frame. Gravity-corrected, world reference frame-corrected Y axis acceleration data is accessible via the getWorldLinearAccelY() method.

Returns:

Returns the current acceleration rate (in G).

getRawAccelZ() → float

Returns the current raw (unprocessed) Z-axis acceleration rate (in G).

Note

this value is unprocessed, and should only be accessed by advanced users. This raw value has not had acceleration due to gravity removed from it, and has not been rotated to the world reference frame. Gravity-corrected, world reference frame-corrected Z axis acceleration data is accessible via the getWorldLinearAccelZ() method.

Returns:

Returns the current acceleration rate (in G).

getRawGyroX() → float

Returns the current raw (unprocessed) X-axis gyro rotation rate (in degrees/sec).

Note

This value is un-processed, and should only be accessed by advanced users. Typically, rotation about the X Axis is referred to as “Pitch”. Calibrated and Integrated Pitch data is accessible via the getPitch() method.

Returns:

Returns the current rotation rate (in degrees/sec).

getRawGyroY() → float

Returns the current raw (unprocessed) Y-axis gyro rotation rate (in degrees/sec).

Note

This value is un-processed, and should only be accessed by advanced users. Typically, rotation about the T Axis is referred to as “Roll”. Calibrated and Integrated Pitch data is accessible via the getRoll() method.

Returns:

Returns the current rotation rate (in degrees/sec).

getRawGyroZ() → float

Returns the current raw (unprocessed) Z-axis gyro rotation rate (in degrees/sec).

Note

This value is un-processed, and should only be accessed by advanced users. Typically, rotation about the T Axis is referred to as “Yaw”. Calibrated and Integrated Pitch data is accessible via the getYaw() method.

Returns:

Returns the current rotation rate (in degrees/sec).

getRawMagX() → float

Returns the current raw (unprocessed) X-axis magnetometer reading (in uTesla).

Note

this value is unprocessed, and should only be accessed by advanced users. This raw value has not been tilt-corrected, and has not been combined with the other magnetometer axis data to yield a compass heading. Tilt-corrected compass heading data is accessible via the getCompassHeading() method.

Returns:

Returns the mag field strength (in uTesla).

getRawMagY() → float

Returns the current raw (unprocessed) Y-axis magnetometer reading (in uTesla).

Note

this value is unprocessed, and should only be accessed by advanced users. This raw value has not been tilt-corrected, and has not been combined with the other magnetometer axis data to yield a compass heading. Tilt-corrected compass heading data is accessible via the getCompassHeading() method.

Returns:

Returns the mag field strength (in uTesla).

getRawMagZ() → float

Returns the current raw (unprocessed) Z-axis magnetometer reading (in uTesla).

Note

this value is unprocessed, and should only be accessed by advanced users. This raw value has not been tilt-corrected, and has not been combined with the other magnetometer axis data to yield a compass heading. Tilt-corrected compass heading data is accessible via the getCompassHeading() method.

Returns:

Returns the mag field strength (in uTesla).

getRequestedUpdateRate() → int

Returns the currently requested update rate. rate. Note that not every update rate can actually be realized, since the actual update rate must be a value evenly divisible by the navX-Model device’s internal motion processor sample clock (200Hz).

To determine the actual update rate, use the getActualUpdateRate() method.

Returns:

Returns the requested update rate in Hz (cycles per second).

getRoll() → float

Returns the current roll value (in degrees, from -180 to 180) reported by the sensor. Roll is a measure of rotation around the X Axis.

Returns:

The current roll value in degrees (-180 to 180).

getTempC() → float

Returns the current temperature (in degrees centigrade) reported by the sensor’s gyro/accelerometer circuit.

This value may be useful in order to perform advanced temperature- correction of raw gyroscope and accelerometer values.

Returns:

The current temperature (in degrees centigrade).

getUpdateCount() → float

Returns the count of valid updates which have been received from the sensor. This count should increase at the same rate indicated by the configured update rate.

Returns:

The number of valid updates received from the sensor.

getVelocityX() → float

Returns the velocity (in meters/sec) of the X axis [Experimental].

Note

This feature is experimental. Velocity measures rely on integration of acceleration values from MEMS accelerometers which yield “noisy” values. The resulting velocities are not known to be very accurate.

Returns:

Current Velocity (in meters/squared).

getVelocityY() → float

Returns the velocity (in meters/sec) of the Y axis [Experimental].

Note

This feature is experimental. Velocity measures rely on integration of acceleration values from MEMS accelerometers which yield “noisy” values. The resulting velocities are not known to be very accurate.

Returns:

Current Velocity (in meters/squared).

getVelocityZ() → float

Returns the velocity (in meters/sec) of the X axis [Experimental].

Note

This feature is experimental. Velocity measures rely on integration of acceleration values from MEMS accelerometers which yield “noisy” values. The resulting velocities are not known to be very accurate.

Returns:

Current Velocity (in meters/squared).

getWorldLinearAccelX() → float

Returns the current linear acceleration in the X-axis (in G).

World linear acceleration refers to raw acceleration data, which has had the gravity component removed, and which has been rotated to the same reference frame as the current yaw value. The resulting value represents the current acceleration in the x-axis of the body (e.g., the robot) on which the sensor is mounted.

Returns:

Current world linear acceleration in the X-axis (in G).

getWorldLinearAccelY() → float

Returns the current linear acceleration in the Y-axis (in G).

World linear acceleration refers to raw acceleration data, which has had the gravity component removed, and which has been rotated to the same reference frame as the current yaw value. The resulting value represents the current acceleration in the Y-axis of the body (e.g., the robot) on which the sensor is mounted.

Returns:

Current world linear acceleration in the Y-axis (in G).

getWorldLinearAccelZ() → float

Returns the current linear acceleration in the Z-axis (in G).

World linear acceleration refers to raw acceleration data, which has had the gravity component removed, and which has been rotated to the same reference frame as the current yaw value. The resulting value represents the current acceleration in the Z-axis of the body (e.g., the robot) on which the sensor is mounted.

Returns:

Current world linear acceleration in the Z-axis (in G).

getYaw() → float

Returns the current yaw value (in degrees, from -180 to 180) reported by the sensor. Yaw is a measure of rotation around the Z Axis (which is perpendicular to the earth).

Note that the returned yaw value will be offset by a user-specified offset value this user-specified offset value is set by invoking the zeroYaw() method.

Returns:

The current yaw value in degrees (-180 to 180).

isAltitudeValid() → bool

Indicates whether the current altitude (and barometric pressure) data is valid. This value will only be true for a sensor with an onboard pressure sensor installed.

If this value is false for a board with an installed pressure sensor, this indicates a malfunction of the onboard pressure sensor.

Returns:

Returns true if a working pressure sensor is installed.

isBoardlevelYawResetEnabled() → bool

Returns true if Board-level yaw resets are enabled. Conversely, returns false if Software-based yaw resets are active.

Returns:

true if Board-level yaw resets are enabled.

isCalibrating() → bool

Returns true if the sensor is currently performing automatic gyro/accelerometer calibration. Automatic calibration occurs when the sensor is initially powered on, during which time the sensor should be held still, with the Z-axis pointing up (perpendicular to the earth).

Note

During this automatic calibration, the yaw, pitch and roll values returned may not be accurate.

Once calibration is complete, the sensor will automatically remove an internal yaw offset value from all reported values.

Returns:

Returns true if the sensor is currently automatically calibrating the gyro and accelerometer sensors.

isConnected() → bool

Indicates whether the sensor is currently connected to the host computer. A connection is considered established whenever communication with the sensor has occurred recently.

Returns:

Returns true if a valid update has been recently received from the sensor.

isMagneticDisturbance() → bool

Indicates whether the current magnetic field strength diverges from the calibrated value for the earth’s magnetic field by more than the currently- configured Magnetic Disturbance Ratio.

This function will always return false if the sensor’s magnetometer has not yet been calibrated (see isMagnetometerCalibrated()).

Returns:

true if a magnetic disturbance is detected (or the magnetometer is uncalibrated).

isMagnetometerCalibrated() → bool

Indicates whether the magnetometer has been calibrated.

Magnetometer Calibration must be performed by the user.

Note that if this function does indicate the magnetometer is calibrated, this does not necessarily mean that the calibration quality is sufficient to yield valid compass headings.

Returns:

Returns true if magnetometer calibration has been performed.

isMoving() → bool

Indicates if the sensor is currently detecting motion, based upon the X and Y-axis world linear acceleration values. If the sum of the absolute values of the X and Y axis exceed a “motion threshold”, the motion state is indicated.

Returns:

Returns true if the sensor is currently detecting motion.

isRotating() → bool

Indicates if the sensor is currently detecting motion, based upon the X and Y-axis world linear acceleration values. If the sum of the absolute values of the X and Y axis exceed a “motion threshold”, the motion state is indicated.

Returns:

Returns true if the sensor is currently detecting motion.

reset() → None

Reset the Yaw gyro.

Resets the Gyro Z (Yaw) axis to a heading of zero. This can be used if there is significant drift in the gyro and it needs to be recalibrated after it has been running.

resetDisplacement() → None

Zeros the displacement integration variables. Invoke this at the moment when integration begins.

setAngleAdjustment(angle: float) → None

Sets an amount of angle to be automatically added before returning a angle from the getAngle() method. This allows users of the getAngle method to logically rotate the sensor by a given amount of degrees.

NOTE 1: The adjustment angle is only applied to the value returned from getAngle - it does not adjust the value returned from getYaw(), nor any of the quaternion values.

NOTE 2: The adjustment angle is not automatically cleared whenever the sensor yaw angle is reset.

If not set, the default adjustment angle is 0 degrees (no adjustment).

Parameters:

adjustment – Adjustment in degrees (range: -360 to 360)

updateDisplacement(accel_x_g: float, accel_y_g: float, update_rate_hz: int, is_moving: bool) → None

zeroYaw() → None

Sets the user-specified yaw offset to the current yaw value reported by the sensor.

This user-specified yaw offset is automatically subtracted from subsequent yaw values reported by the getYaw() method.