Summary

This sensor was designed specifically for the motor racing industry. It meets the demands of the harsh environment experienced in modern motorsport. One particular application of the sensor (in the Australian V8 Supercar seires) has seen these sensors do four seasons of service - their prior sensors only managed about nine months of service before failing due to vibration.

The sensor is a three-axis (X, Y, Z) sensor with each axis orthogonal to the others, measuring positive and negative forces in each of the 3 axes.

The development of this sensor had the following design goals:

1. G-Force, Gyroscopic & Magnetic Sensing
2. Triple axis sensing of all parameters
3. CAN Bus Output - due to the number of data channels
4. High level of customisation of the data output
5. Flexible CAN bus address and data rates
6. Rugged design
7. Cost competitive

History

Jacobs Design has had a long involvement with the Australian V8 Supercars in a scrutineering role primarily focused on the electronic and data acquisition systems. The use of gyros had for a long time been banned from V8 Supercars due to their expense and the level of expertise required by data engineers in the analysis of the data gathered by these sensors. In the current era, all V8 Supercars teams have access to excellent data engineers.

The 3Force sensor was developed in late 2011, following on from many years of successful use of the g-force sensors in the motorsport environment. Building from the mechanical reliability of the g-force sensor, the 3Force sensor is a technological leap, incorporating gyroscopic as well as magnetic sensing in the same housing as the original sensor.

General Specifications

Parameter Minimum Typical Maximum Units CAN Speed (See note 1) 125K - 1M baud Supply Voltage (See notes 2, 3) 6 - 24 V Sensor Supply Supply Current - 20 40 mA Operational Temperature -20 - 70 degrees C   Weight <55 grams (including pigtail) Enclosure Material Aluminium 6016-T6 (Anodised) Heatshrink Raychem DR-25 Connector Wire Mil-W-22759/16

G-Force (Acceleration) Sensor

Parameter Minimum Typical Maximum Units Measurement Range (16g option) - 16 - g Stability - +/-0.015 - % per degree C Nonlinearity - +/-0.3 - % Inter-Axis Alignment Errors - +/-0.1 - % Cross-Axis Sensitivity - +/-1 - % CAN Bus Rate 1 50 500 Hz   Reported Resolution 1 milli-g (1000 counts per 1g)

Gyroscopic (Rotation) Sensor

Parameter Minimum Typical Maximum Units Measurement Range - 500 - degrees per second CAN Bus Rate 1 50 500 Hz   Reported Resolution 0.1 degrees per second Internal Sample Rate 800 Hz

Magnetic (Compass) Sensor

The sensor is capable of detecting the earths magnetic field, although it is affected by the presence of ferrous objects at very short range. Parameter Minimum Typical Maximum Units CAN Bus Rate 1 20 100 Hz   Internal Sample Rate 75 Hz

Notes:

1. The CAN bus speed is selected when the sensor is purchased. The CAN bus speed may be changed at a later stage.
2. DO NOT connect the sensor directly to the vehicle battery. The sensor is not capable of dissipating the energy caused by load dump conditions.
3. The sensor will typically operate down to a supply voltage of 4.2V. However, as the supply voltage gets lower the quality of the supply becomes increasingly critical. In vehicle powered systems it is not recommended to go below 5V supply, in addition, if the sensors suffers from drop-outs at these levels then some form of voltage buffering or extra capacitance may be required at the sensor.

Wiring the 3Force Sensor

The sensor requires a supply voltage of 5 to 24 Volts, which must be from a protected source. DO NOT connect the sensor directly to the vehicle battery. The 3Force outputs are generated as messages on the CAN bus. Their is no CAN termination resistor in the sensor. The sensor is supplied with a pigtail loom.

Red - Supply Voltage (5V to 24V) Green - CAN High / CAN + Blue - CAN Low / CAN - Black - 0V / Chassis

Mounting the 3Force Sensor

(all dimensions in mm)

Double sided tape or Velcro may be used to mount the sensor when an amount of "shock filtering" is required. M4 countersunk bolts may be used to mount the sensor when a more direct coupling is required. Excessive vibration "may" swamp the g-force measurements. However, this method of mounting has proven successful in a V8 Supercar (with the sensor mounted to the driveshaft tunnel).
Rigid mounting is recommended for the 100g sensor.
The top view of the accelerometer is as follows:

Available Downloads

• Brief Data Sheet - PDF Document
• Full Data Sheet - PDF Document

Configuring the Data Aquisition System

Refer to the document 3Force Data Sheet for further details on how to configure your data acquisition system (abbrev. DAS).

Calibrating the 3Force Sensor

There are two methods that may be used to calibrate the 3Force sensor. A software compensation may be applied in the DAS, or the sensor can have its calibration updated.

Software Compensation

In the CAN bus template of the DAS, there would normally be factors for converting the sensor value from an integer value (as transmitted by the sensor) to a floating point value (as used by the DAS). These compensation values, typically just simple offset and magnitude numbers, may be adjusted to effectively calibrate the equipment without needing any special know-how.

Sensor Calibration

The 3Force Data Sheet documents all the CAN messages required to calibrate the sensor.

3Force AU$660.00 Price in US Dollars Price in GB Pounds Price in Euros G-Force Bandwidth 1Hz 5Hz10Hz20Hz 50Hz100Hz 200Hz (Default)500Hz CAN Bus Address(es) G-Force Output Rate 1Hz2Hz 5Hz10Hz20Hz 50Hz (Default)100Hz 200Hz500Hz Gyro Output Rate 1Hz2Hz 5Hz10Hz20Hz 50Hz (Default)100Hz 200Hz500Hz Comapss Output Rate 1Hz2Hz 5Hz10Hz 20Hz (Default) 50Hz100Hz CAN Bus Speed 125K250K500K 1M (Default) PayPal Security!

Notes 1) The G-Force Bandwidth is set in hardware and sealed into the sensor, and NOT able to be changed once the sensor has been shipped. The default value has been selected as the best all round compromise between sensor measurement range, sensitivity and vibrational noise immunity. 2) All the other parameters are able to be set to different values at a later date. However, a CAN interface device is required to change the sensor settings, so choose wisely if you want to get started with the sensor without too much delay. Commercial Terms • Price includes postage - local and international • Price includes GST - for Autralian customers • Import duties and taxes are the responsibility of the purchaser • All sensors come with a 12 month warranty • Discounts apply for bulk purchases - contact us for further details.