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Changes for page Sensor Module

Last modified by Heimir Thordarson on 2026/07/05 12:56
From version 67.6
edited by Heimir Thordarson
on 2026/07/05 12:56
Change comment: There is no comment for this version
To version 64.6
edited by Heimir Thordarson
on 2026/03/23 18:48
Change comment: There is no comment for this version

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... ... @@ -250,53 +250,10 @@
250 250  
251 251  The sensors output latency can be expected to be a lot shorter than the oil temperature sensor as the sensor is just a variable sensor based on placement. The limiting factor for the system which uses this information is the CAN-BUS messages from the inverters which send the information each 6.25 milliseconds. This means that the cut-off frequency cannot be any lower than 160 Hz, which will make the same type of low pass filter from the oil temperature sensor acceptable with a cut-off frequency of 1591 Hz.
252 252  
253 -== Cooling System Sensor ==
253 +== Air Temperature Sensor ==
254 254  
255 -There will be four cooling system sensor on the AR26 vehicle, and all of the sensors include two measurements each. These two signals are water temperature and pressure. With this the temperature delta over the entire cooling system can be measured, but also the overall water flow. If the equivalent orifice of the motors, inverters and other components are known, the flow can be calculated using the orifice equation.
255 +The main goal of the air temperature sensor is to have an onboard knowledge of the ambient temperature for datalogging and cooling system control system. The sensor is a [[GA10K4D25>>doc:.GA10K4D25.WebHome]] from TE connectivity, which is a NTC thermistor which requires some extra circuitry to ensure that the microcontroller can measure the change in resistance of the thermistor.
256 256  
257 -
258 -(% style="font-size: 1.5em;" %)
259 -(((
260 -{{mathjax}}
261 -$$
262 -Q = C_D \cdot A_D \sqrt{\frac{2 \cdot \Delta P}{\rho}}
263 -$$
264 -{{/mathjax}}
265 -)))
266 -
267 -
268 -where:
269 -
270 -* {{mathjax}}\(Q\){{/mathjax}}= Waterflow through the equivalent orifice
271 -* {{mathjax}}\(C_D \cdot A_D\){{/mathjax}}= practical cross section of the orifice
272 -* {{mathjax}}\(\Delta P\){{/mathjax}}= Pressure difference between the two pressure sensors
273 -* {{mathjax}}\(\rho\){{/mathjax}}= Density of the cooling liquid
274 -
275 -The sensor used on the AR26 car is the [[Bosch Motorsport PST-F 1>>https://www.bosch-motorsport.de/content/downloads/Raceparts/Resources/pdf/Data%20Sheet_70496907_Pressure_Sensor_Combined_PST-F_1.pdf]] and has the following transfer function for the output voltages based on pressure and temperature.
276 -
277 -=== Pressure sensor ===
278 -
279 -The pressure sensor build into the PST-F 1 has an supply voltage of 5 volts and has a output voltage range of 0.5 to 4.5 volts. The following formula shows the pressure based on the output voltage.
280 -
281 -{{mathjax}}
282 -$$
283 -P = 2.5 \cdot V - \frac{5}{4}
284 -$$
285 -{{/mathjax}}
286 -
287 -Where:
288 -
289 -* {{mathjax}}\(P\){{/mathjax}} = Pressure from pressure sensor [bar]
290 -* {{mathjax}}\(V\){{/mathjax}} = Voltage output from the pressure sensor [volts]
291 -
292 -
293 -
294 -= Alternative Usecases =
295 -
296 -For the AR26 sensor module, it proved itself being useful in taking extra task if any other systems stopped working. During the Vehicel Status Video (VSV) was the sensor module used as the Vehicle Control Unit (VCU), but did not measure all of the sensors which the original VCU was intended to measure. Considering that the suspension displacent and Acceleratior Pedal Position Sensors (APPS) are both potentiometers, can these be connected the same way so that the sensor module can measure the APPS. The sensor module is also designed to measure four pressure sensors for the cooling system which work on 5V, which luckily enough is also what the brake pressure sensors are running on. This means that the sensor module can measure the brake pressure by connecting them simularly to the module as the cooling pressure.
297 -
298 -The sensor module on the other hand is not designed to measure an extra 3 potentiometers which the VCU does. These sensor are the front suspension displacement sensors and the steering angle sensor. The sensor module can measure to an additional 5 potentiometers with some small changes on the PCB. This is done by using the thermistor inputs, removing the pull-up resistors, and supplying the sensor with 3.3V by conning one of the available pins on the main connector to 3.3V. On the main connector, is that pin number 33 to 42. If the pull-up resistor is not removed will the voltage input into the microcontroller become unlinear and unnecessarily difficult to calculate the length of the potentiometer.
299 -
300 300  = Bill of Materials =
301 301  
302 302  == Circuit Board ==