SensorDynamics' compact wireless module for motion detection in automotive, industrial and medical apps

GRAZ, AUSTRIA: SensorDynamics, a manufacturer and supplier of micro and wireless semiconductor products, has launched a wireless inertial measurement system consisting of a mobile sensor unit and a receiver.

The inertial combo-sensors, RF- and LF-devices used here are all produced by SensorDynamics. The measurement system features an ISM band transceiver chip plus LF transmission chips, enabling mobile unit wakeup by a 21 kHz signal.

By adding optionally obtainable transmitter coils, these LF circuits allow to localize the module at a range of up to 7 meters with 10 cm accuracy. SensorDynamics can deliver both the ready module and expertise in applications for customers wishing to incorporate the discrete chips in their own systems.

The wireless measurement system comes with a calibrated range of ±300°/s for rotary rate and ±2 g for acceleration on all three spatial axes. Outside the calibrated range, it is even possible to detect motion of up to 512°/s and ±6.78 g. The mobile unit withstands shock up to 2000 g, and the sensors feature a continuous self-diagnostic functionality, ensuring high fail-safety of the system. The mobile unit integrates a 2D compass for determination of absolute orientation.

Synchronous wireless transmission of the measured values uses standard FMSK modulation in the 433 MHz band. The high data transmission rate of up 125 Kbps can carry all six 100 Hz measured values.

The SD340 RF transceiver used here has a 32 Kbyte flash memory that can be used to execute custom programs such as encoding algorithms, conditioning of measured values or automatic channel switchover. The mobile unit, scaled 30x85x8 mm³, will operate 8 hours on a 1000 mAh battery. The module operating temperature range is -40 to +85°C.

The receiver unit provides the measurement data via UART interface and supports a variety of antennas. A transmission range of more than 150 meters is possible.

The inertial measurement system is suitable for automotive, industrial and medical applications calling for a compact device to wirelessly detect motion or do away with connectors and cable harness. A typical example is detecting the motion of agricultural machinery that has to be towed by different kinds of tractor, making connectors impractical.