Surfer is the name of a product line of highly accurate, affordable Inertial Measurement Units (IMU). The IMU is a full 3D sensor, allowing measurements in three perpendicular directions. The unit has three gyros, three accelerometers and a temperature sensor. The offsets of the (x & y) gyro axis and (x & y) accelerometer axis (green lines in the figure on the right) are continuously estimated and compensated by the proprietary DriftLess+ algorithm. This virtually eliminates the offsets of the x- and y-axis, independent of temperature changes. The z-axes of the gyro and accelerometer (indicated by the red line in the figure) are not corrected.

The unit acts as a full 3D- IMU and is fully calibrated. It connects to a host with a standard, 3-wire, serial RS232 connection (TxD,RxD,GND). All gyro and accelerometer measurements are output in floating point numerical format at max. 500 Hz sampling frequency.

The Surfer product line comes in different sizes and performance versions. The size of the currently available unit is 5x5x5 cm, power consumption is less then 500mW at 5V supply voltage. A smaller 3x3x3 cm version is under development.
Typical application of these IMU’s is for camera stabilization, vehicle navigation/heading tracking.

GNC Solutions is looking for partners to produce this technology and bring it to the market.

1 The basic evaluation version Surfer5 (product number DL2D5X5) has residual gyro offsets of 25 deg/hr and residual accelerometer offsets are 2.5 mm/s2. All these values are 1-sigma standard deviation. Gyro z-axis and accelerometer z-axis of these units are not corrected for offsets. The size of the unit is 5x5x5 cm, power consumption is less then 500mW at a 5V supply voltage. This evaluation version is available at an affordable price. Contact us for current prices.
2 The medium performance version Surfer5-1 (product number DL2D5X5-1) is identical to the basic version but has improved gyro performance. It has residual gyro offsets of 15 deg/hr, 1-sigma standard deviation. Evaluation versions of this medium performance unit are available. Contact us for current prices.
3 The high performance version Surfer5-2 (product number DL2D5X5-2) is also identical to the basic version and has even further improved gyro performance. It has residual gyro offsets of 5 deg/hr, 1-sigma standard deviation. This version is still under development.
As an example of the performance of this unit, the figure on the right shows a typical result of the angular error as a function of time of this high performance version. In this example, the unit was rotated in a random way using a two-axis rotation table and rotation angles were reconstructed using the Surfer5-2 IMU. The dashed line in the plot is the 2-sigma boundary of the Angular Random Walk (ARW). For practical reasons, this dashed line may be considered as a performance boundary. Any drift below this boundary, may be considered as simply the result of noise. Further improvements are senseless.
4 A smaller sized version Surfer3-x of only 3x3x3 cm, having the same performance specifications, is currently under development.
5 A low-power version (product number DL2D5X5t) has also been developped. This version has comparable performance specifications as the other units but at a much lower (approx. 100 mW power consumption).

Key specifications:

Main unit
Dimensions (HxBxD)
Weight
Power supply
Operating temperature range
Sampling rate
Communication
50x50x50 mm
150g
5V, <0.5W  (5V,<0.1W for the DL2D5X5t version)
-30 to 80 °C
10 to 500 Hz (Higher rates on request)
Serial RS232 (RS485, RS422 or other on request)
Gyroscopes
Measurement range
Noise PSD, ARW
Total residual bias (1,2)
Surfer, basic evaluation version
Surfer-1, medium performance evaluation version
Surfer-2 high performance evaluation version
±250, ±500, ±1000, ±2000 deg/s
0.5 deg/rt (hr)25 deg/hr25 deg/hr
15 deg/hr
5 deg/hr
Accelerometers
Measurement range
Noise PSD, VRW
Total residual bias (1,2)
±2, ±4, ±8, ±16 g
500 µg/rt (Hz) , 0.3 m/s/rt (hr)
250 µg

Notes:
1. The total bias includes all biases like turn-on bias, in-run bias fluctuations, temperature fluctuations and other random fluctuations.
2. 1-σ standard deviation