IMU (100 Hz, 8 byte)

Configuration file fields

This section is autogenerated from the Rule Schema.

IMU orientation (10 ms) output.imu

State output.imu.state

Type	Default	Options
integer	1	Disable: 0 Enable: 1

ID Format output.imu.id_format

ID format of the message

Type	Default	Options
integer	0	Standard (11-bit): 0 Extended (29-bit): 1

Message ID (hex) output.imu.id

ID of the message in hex. Example: 00435354.

Type	Default
string	01

Trigger method output.imu.trigger

Transmission trigger method. Push: Signal is periodically transmitted. Poll: Signal is transmitted on request

Type	Default	Options
integer	0	Push: 0 Poll: 1

---

IMU coordinate system

The coordinate system defines the axis used by the IMU sensors.

The IMU coordinate system (right-handed)

---

Frame layout

Note

The frame layout is defined in the CANmod.gps DBC file

The IMU frame contains 3 x acceleration + 3 x angular rate.

Note

The IMU output results are rotated according to the angles entered in IMU mount alignment

Name	Bitpos	Length	Factor	Offset	Min	Max	Unit
ImuValid	0	1	1	0	0	1
AccelerationX	1	10	0.125	-64	-64	63.875	\(\texttt{ m/s}^2\)
AccelerationY	11	10	0.125	-64	-64	63.875	\(\texttt{ m/s}^2\)
AccelerationZ	21	10	0.125	-64	-64	63.875	\(\texttt{ m/s}^2\)
AngularRateX	31	11	0.25	-256	-256	255.75	\(\texttt{ deg/s}\)
AngularRateY	42	11	0.25	-256	-256	255.75	\(\texttt{ deg/s}\)
AngularRateZ	53	11	0.25	-256	-256	255.75	\(\texttt{ deg/s}\)

ImuValid

The ImuValid signal can take one of the following values:

• 0: Invalid

• 1: Valid

AccelerationX, AccelerationY, AccelerationZ

AccelerationX, AccelerationY, AccelerationZ express linear acceleration in\(\texttt{ m/s}^2\) along the device X, Y and Z axis respectively.

Note

The acceleration measurements include a constant component from gravity. With the device at standstill, the gravity vector becomes \([x, y, z]^T \approx [0, 0, 9.82]^T\) [1].

AngularRateX, AngularRateY, AngularRateZ

AngularRateX, AngularRateY, AngularRateZ express the angular rate in\(\texttt{ deg/s}\) around the device X, Y and Z axis respectively.

Note

Note that AccelerationX, AccelerationY, AccelerationZ express linear acceleration while AngularRateX, AngularRateY, AngularRateZ express angular rotational speed.

Decoding example

Raw IMU frame payload:

• Hex: 0144103F00A2107B (byte 0 to the left)

• Hex reversed: 7B10A2003F104401 (byte 0 to the right)

• Bin: 01111011000 10000101000 10000000000 0111111000 1000001000 1000000000 1 (bit 0 to the right)

	AngularRateZ(11)	AngularRateY(11)	AngularRateX(11)	AccelerationZ(10)	AccelerationY(10)	AccelerationX(10)	ImuValid(1)
Raw (bin)	01111011000	10000101000	10000000000	0111111000	1000001000	1000000000	1
Raw (dec)	984	1064	1024	504	520	512	1
Scaled	246.0	266.0	256.0	63.0	65.0	64.0	1
Offset	-10.0	10.0	0.0	-1.0	1.0	0.0	1

• AccelerationX: \(0.0\texttt{ m/s}^2\)

• AccelerationY: \(1.0\texttt{ m/s}^2\)

• AccelerationZ: \(-1.0\texttt{ m/s}^2\)

• AngularRateX: \(0.0\texttt{ deg/s}\)

• AngularRateY: \(10.0\texttt{ deg/s}\)

• AngularRateZ: \(-10.0\texttt{ deg/s}\)

The device accelerates by \(1.0\texttt{ m/s}^2\) along the Y axis and by \(-1.0\texttt{ m/s}^2\) along Z. At the same time, the device rotates by \(10.0\texttt{ deg/s}\) around Y axis and \(-10.0\texttt{ deg/s}\) around the Z axis.

---

[1]

The direction of the gravity vector at standstill may seem counter-intuitive (it points up along the z-axis). The measured acceleration is not gravity directly, but rather the acceleration provided by the surface acting on the device - which cancels out the gravity.