Navigation Module

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The Navigation Module (NM) is an electronic schematic board, designed to supply recent changes in physical position and orientation of the Robot based on information, supplied by inertial MEMS sensors.

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Contents

Analog sensors

3 axis gyro

Model: SOC Robotics, RG30, Three Axis Rate Gyro.
Sensor: Epson Toyocom XV-3500CB.

Source voltage: 3.3V
Output zero level: 1.75 V
Output range after amplification: 1.75 V ± 1.47 V = [0.28V min; 3.22V max]

Measurement range: ±100 deg/sec = ±1.745329252 radians/sec
Frequency response: 200 Hz (90 deg delay)

Temperature range: -20 .. +80 °C
Current consumption: 6.0 mA max

Dimensions: 2.54 cm x 2.463 cm = [1.00 x 0.97 in]
Weight: 8 grams

Usable calculations

1.47V = 100 [deg/s] => 0.0147 [V] = 1 [deg/s]
1 [rad] = 180/PI [deg] => 0.0147 [V]* 180 [deg] / PI [rad] = 0.84224796[V] = 1 [rad/s]
1.0 [V] = 1.187298809 [rad/s]
ADC model: AD7327 - 12bit + sign @ 500kSPS
selected range: -5..0..+5V => sign ignored => 0..+5V
12bits (sign ignored) = 2^12 LSB = 4096 LSB
+5V = 4096 LSBs
1 [bit LSB] = 4096 [bits LSB] / 5 [V] = 0.001220703 [V]
1 [bit LSB] = 0.001220703 [V] * 1.187298809 [(rad/s)/V] = 0.001449339 [rad/s]
Given:
adc_result = 2192
adc_zero_offset = {1.65/5 * 4096} = 1352
sensitivity = 0.001449339 [(rad/s)/bit_LSB]
Goal:
rate-?
Solution:
delta = adc_result - adc_zero_offset = 2192-1352 = 777 [bits LSBs]
rate = delta*sensitivity = 777*0.001449339 = 1.126136403 [rad/s]

3 axis accelerometer

Model: Sure Electronics, DC-SS009, Ver 2.0.
Sensor: Freescale Semiconductor MMA7260QT

Source voltage: 3.3V
Output zero level: 1.65 V (typical) = [1.485 V min, 1.815 V max]
Output range: 1.65 V ± 1.2 V = [0.45V min; 2.85V max]

Sensitivity (Range = ±1.5 g): 0.800 V/g. Sensitivity <x,y,z> = <±0.02,±0.01,±0.00> (typical)
Sensitivity (Range = ±2.0 g): 0.600 V/g
Sensitivity (Range = ±4.0 g): 0.300 V/g
Sensitivity (Range = ±6.0 g): 0.200 V/g
Bandwidth response: <x,y,z> = <350 Hz, 350 Hz, 150 Hz>
Internal sampling frequency: 11 KHz

Current consumption: 800 uA max
Temperature range: -40 .. +105 °C
Temperature sensor output deviation (max value): <x,y,z> = <3.8, 5.9, 1.0> mg/°C

Schematic capture

Schematic capture of the Navigation Module

PCB

Two-sided PCB is shown below:

PCB image of the Navigation Module

Device photo

Photo of the completely soldered and mounted Navigation Module

Test results

See also

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