SDI-MAHRS-3D
A mobile orientation sensor designed for tracking an object angular motion. Low cost, small dimensions, low power consumption, casing made of special plastic and an ability to operate within a wide temperature range makes MAHRS-3D a perfect instrument for the purposes of determination and tracking the angular motion of objects, such as: humans, Head Mounted Displays, robots, positioning devices.
Operation of MAHRS-3D is based on the integration of nine inertial sensing elements: three three-axis accelerometer, gyro, and magnetometer units. A sensor-embedded DSP designed for processing sensing element output allows tracking of angular motion for an object within a full angle range of 360 deg. Orientation update rate - 500Hz.
Option for changing dynamic characteristics of Kalman filter and angular sensitivity. Software for elimination of magnetic deviations and course updating.
MAHRS-3D is a small-scale angular orientation sensor. Operation within a full angle range of 360 deg in all three axes, low power consumption, integration of nine miniature inertial sensing elements by processing with an adaptive Kalman filter, algorithm for elimination of magnetic deviation and course updates.
Application:
Land Vehicle Control
Remotely Operated Vehicles
Avionics System
Platform Stabilization
Robotics
Specification
Performance Data
Degrees of Freedom 3 (Yaw, Pitch and Roll, only Quaternion modes)
Angular Range Full 360° - All Axes
Orientation Angular Resolution < 0.01°
RMS Accuracy 1° in yaw, 0.03° in pitch & roll at 25°C
Gyros range ±1200° per second
Gyro Nonlinearity 0.1%
Gyro Bias Stability 0.7 deg/sec
Accelerometer range ±1.7 G's
Accelerometer Nonlinearity 0.2%
Accelerometer Bias Stability 0.03 G's
Magnetometer range ±1.0 Gauss FS
Magnetometer Nonlinearity 0.1%
Magnetometer Bias Stability 0.2%
Analog Output Option No
Operating Temperature 0ºC ..+70 ºC
Size 32 x 60 x 15 mm
Update Rate 100Hz (500Hz Raw data, 100Hz Quaternion)
Operating voltage 5.1 - 5.7 V
Power consumption 450 mW
Wired receiver interface RS-485(LVDS), 1000 kbaud (external USB adapter)
Software support Full SDK for Windows 2000/XP/2003
1. Connection of the mini AHRS.
Fig1-1. MAHRS-3D connectors view. MAHRS-3D sensors have two 4-pin connectors, contacts of which are connected in parallel (1-1, 2-2, 3-3, 4-4)
Table 1-1. Pins layout:
Number Name Function Parameters
1 +5V6 input, supply voltage +5.1-5.7V @ 80mA
2 GND Ground, shield
3 A input/output, A RS-485 BaudRate=1 Mbps, R=120?
4 B input/output, B RS-485 BaudRate=1 Mbps, R=120?
2. Communications protocol.
2.1. Physical level:
Standard: TIA/EIA?485A (half-duplex)
BaudRate: 1 Mbps
ByteSize: 8 bits
StopBits: 1 bit
Parity: No
2.2. Transport level.
The communications protocol is optimized to work with16-bit words. Each word consists of two bytes, the first byte is the least significant one, and the second one is the most significant one.
Table 2-1. Protocol transport level data:
Number Name Value Description
1 Id 0x55AA Packet header identifier
2 Len 8-65534 Packet byte counter, from Id to CS.
3 Data1 0-65535 Data
XX DataXX 0-65535 Data
XX DataXX 0-65535 Data
N+2 DataN 0-65535 Data
N+3 Cs 0-65535 Checksum, sum of words from Id to DataN.
- Pause >20uS Pause is necessary to identify a packet using the sensor.
If the pause between byte in packet is bigger than 10uS this packet will be ignored by sensor.
2.3.Output data packets.
2.3.1. Data in the Raw Data mode.
In this mode data is output without any processing, directly from the ADC.
Table 2-2. Raw data packet:
Transport Name Value Notation Description
Data1 Type 0x0210 unsigned word packet type
Data2 Cntr* 0-65535 unsig
