raisim::InertialMeasurementUnit

final class · #include <raisim/sensors/InertialMeasurementUnit.hpp>

Inherits: raisim::Sensor

An ideal or stochastic six-axis IMU. Measurements use the completed physics state. Orientation is ground truth, not an attitude estimate. No inverse-dynamics setting is required. Sampling is limited to one acquisition per physics step, with a phase-preserving clock.

Nested classes

• struct ChannelProperties — Sensor-frame bias, bandwidth, stochastic errors and quantization for one channel.
• struct ImuProperties — Complete IMU measurement model. All model effects are disabled by default.

Constructors & destructor

InertialMeasurementUnit

explicit InertialMeasurementUnit(
    const ImuProperties &prop,
    ArticulatedSystem *as,
    const Vec<3> &pos,
    const Mat<3, 3> &rot)

Create a physics-backed IMU mounted at pos/rot on the owning articulated system.

Parameters

Parameter	Description
prop	Measurement settings and immutable sensor identity.
as	Owning system; may be null until attachment.
pos	Mount position relative to its body.
rot	Sensor-to-body rotation.

~InertialMeasurementUnit

~InertialMeasurementUnit() final = default

Release model state and pending delayed samples.

Public member functions

serializeProp

server::BoundedWriter serializeProp(server::BoundedWriter data) const final

Write sensor metadata using the existing server wire format.

serializeMeasurements

server::BoundedWriter serializeMeasurements(server::BoundedWriter data) const final

Write delivered accelerometer and gyro samples as floats.

getLinearAcceleration

const Eigen::Vector3d &getLinearAcceleration() const

Specific force (acceleration minus gravity) in the IMU frame [m/s^2].

getAngularVelocity

const Eigen::Vector3d &getAngularVelocity() const

Angular velocity in the IMU frame [rad/s].

getOrientation

const Vec<4> &getOrientation() const

Ground-truth sensor-to-world quaternion (w, x, y, z) at the delivered acquisition time.

getGroundTruthOrientation

const Vec<4> &getGroundTruthOrientation() const

Ground-truth orientation at acquisition; identical to getOrientation().

getDeliveryTimeStamp

double getDeliveryTimeStamp() const

World time when the most recent sample became available; negative before first delivery.

getAccelerometerBias

const Eigen::Vector3d &getAccelerometerBias() const

Current accelerometer bias, including its random walk, in m/s^2.

getGyroscopeBias

const Eigen::Vector3d &getGyroscopeBias() const

Current gyro bias, including its random walk, in rad/s.

setLinearAcceleration

void setLinearAcceleration(const Eigen::Vector3d &acc)

Write hardware measurements when using MeasurementSource::MANUAL.

setAngularVelocity

void setAngularVelocity(const Eigen::Vector3d &vel)

Write a hardware gyro measurement in the sensor frame [rad/s].

setOrientation

void setOrientation(const Vec<4> &orientation)

Write a hardware sensor-to-world orientation (w, x, y, z).

getProperties

ImuProperties &getProperties()

Legacy mutable access; permanently enables model comparisons on each update. Valid edits reset the model on the next update; invalid edits are restored with a warning. Prefer const access and setProperties(), which rejects invalid edits immediately.

const ImuProperties &getProperties() const

Read settings without enabling legacy mutation tracking.

setProperties

void setProperties(const ImuProperties &prop)

Validate transactionally, then reset filters, bias, clock, pending samples and random stream. Sensor name and full_name must match the identity chosen at construction.

reset

void reset()

Reset measurements and stochastic history using the configured seed and initial biases.

resetNoise

void resetNoise() noexcept

Restart only the random stream from the active seed, sensor identity, owner id and World seed. Preserve bias, filters, acquisition clock, queued samples and measurements.

getDroppedMeasurementCount

uint64_t getDroppedMeasurementCount() const

Samples dropped because the latency queue was full or allocation failed, since reset().

update

void update(World &world) final

Acquire/filter/deliver once for the current physics step; manual sources are untouched.

Static member functions

getType static

static Type getType()

Concrete sensor type: IMU.

Public attributes

kMaxPendingMeasurements

static constexpr size_t kMaxPendingMeasurements

Maximum delayed samples retained per IMU (about 6 MiB). Excess new samples are dropped.

Inherited members

From raisim::Sensor: getArticulatedSystem, getFrameId, getFrameOrientation, getFramePosition, getFullName, getMeasurementSource, getName, getOriInSensorFrame, getPosInSensorFrame, getPosition, getSensorSetModel, getSerialNumber, getUpdateRate, getUpdateTimeStamp, isUpdateDue, lock, lockMutex, MeasurementSource, setAttachmentFrame, setMeasurementSource, setSerialNumber, setUpdateRate, setUpdateTimeStamp, try_lock, Type, unlock, unlockMutex, updatePose