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Changes for page Sensor Module

Last modified by Heimir Thordarson on 2026/07/05 12:56
From version 49.1
edited by Heimir Thordarson
on 2026/01/27 17:57
Change comment: There is no comment for this version
To version 58.3
edited by Heimir Thordarson
on 2026/02/11 19:49
Change comment: There is no comment for this version

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... ... @@ -5,20 +5,21 @@
5 5  Voltage divider Inputs = 2
6 6  3V3 Thermistor Inputs = 7
7 7  5V Pressure Inputs = 4
8 +Communication Protocol = CAN FD
9 +Max Data rate = 1 Mbps
10 +
8 8  {{/wikibox}}
9 9  
13 += Table of Contents =
14 +
10 10  {{content}}
11 11  {{content}}
12 12  {{content}}
13 -{{toc/}}
14 -
15 -
18 +{{toc reference="Electrical.Sensor Module.WebHome"/}}
16 16  {{/content}}
17 17  {{/content}}
18 18  {{/content}}
19 19  
20 -= =
21 -
22 22  = Description =
23 23  
24 24  The Sensor module is designed to measure any extra analog signals rear of the firewall. For AR26, the module is designed to measure two suspension displacement sensors, two oil temperature, four water pressure, four water temperature, and one air temperature sensor. All of the measurements are then transmitted to a CAN network, which there are two of.
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27 27  
28 28  In the following section, how the sensor module is connected will be covered. The connector for the sensor module is a [[High-Density d'sub-44>>https://www.te.com/en/product-2311770-1.html]] which is directly solderen onto the circuit board. The plug needed for this system is the [[204517-3>>doc:Sandbox.TestPage3]], which uses crimps instead of solder cups which is common for the dsub connectors
29 29  
30 -[[image:AR26_ASM pinout.png||height="214" width="457"]]
31 +[[image:AR26_ASM pinout.png||height="287" width="616"]]
31 31  
32 32  In the figure above, the pinout shows how the pins are divided. Each box shows which pins belong together for each usecase, where the red box is the power input. Yellow boxes are for each canbus network, while the green box is for each sensor used in AR26.
33 33  
... ... @@ -85,10 +85,10 @@
85 85  
86 86  Where:
87 87  
88 -* {{mathjax}}\(R_f\){{/mathjax}} = The upper resistor in the voltage divider which stays fixed, which in this case is 4.7k {{mathjax}}\(\Omega\){{/mathjax}}
89 -* {{mathjax}}\(V_{out}\){{/mathjax}} = The voltage over the thermistor, and the voltage that the microcontroller will measure.
90 -* {{mathjax}}\(V_{in}\){{/mathjax}} = The supply voltage of the voltage divider, which in this case is a constant 3.3 {{mathjax}}\(V\){{/mathjax}}
91 -* {{mathjax}}\(R_T\){{/mathjax}} = Resistance of the thermistor
89 +* {{mathjax}}\(R_f\){{/mathjax}}= The upper resistor in the voltage divider which stays fixed, which in this case is 4.7k {{mathjax}}\(\Omega\){{/mathjax}}
90 +* {{mathjax}}\(V_{out}\){{/mathjax}}= The voltage over the thermistor, and the voltage that the microcontroller will measure.
91 +* {{mathjax}}\(V_{in}\){{/mathjax}}= The supply voltage of the voltage divider, which in this case is a constant 3.3 {{mathjax}}\(V\){{/mathjax}}
92 +* {{mathjax}}\(R_T\){{/mathjax}}= Resistance of the thermistor
92 92  
93 93  Knowing this, the resistance of the thermistor can be added into the following equation. This will determine the temperature of the thermistor based on the known resistance and the beta value of the thermistor.
94 94  
... ... @@ -103,10 +103,10 @@
103 103  
104 104  where:
105 105  
106 -* {{mathjax}}\(\beta\){{/mathjax}} = material constant that defines the steepness of its resistance-temperature curve between two temperature points, usually 25/85 degrees celsius. In this case it is 3694 //**K.**//
107 -* {{mathjax}}\(T_0\){{/mathjax}} = The test temperature at which the thermistor is 10k {{mathjax}}\(\Omega\){{/mathjax}}, which in this case is 25 degrees celsius.
108 -* {{mathjax}}\(R_0\){{/mathjax}} = The resistance of the thermistor when it is 25 degrees celsius.
109 -* {{mathjax}}\(R_T\){{/mathjax}} = The current resistance of the thermistor.
107 +* {{mathjax}}\(\beta\){{/mathjax}}= material constant that defines the steepness of its resistance-temperature curve between two temperature points, usually 25/85 degrees celsius. In this case it is 3694 //**K.**//
108 +* {{mathjax}}\(T_0\){{/mathjax}}= The test temperature at which the thermistor is 10k {{mathjax}}\(\Omega\){{/mathjax}}, which in this case is 25 degrees celsius.
109 +* {{mathjax}}\(R_0\){{/mathjax}}= The resistance of the thermistor when it is 25 degrees celsius.
110 +* {{mathjax}}\(R_T\){{/mathjax}}= The live resistance of the thermistor.
110 110  
111 111  === Filtering ===
112 112  
... ... @@ -123,9 +123,9 @@
123 123  
124 124  Where:
125 125  
126 -* {{mathjax}}\(F_c\){{/mathjax}} = Cut-off frequency of the filter. Any noise with a frequency above this will be filtered out.
127 -* {{mathjax}}\(R\){{/mathjax}} = Resistance of the resistor in low-pass filter.
128 -* {{mathjax}}\(C\){{/mathjax}} = Capacitance of the capacitor in the low-pass filter.
127 +* {{mathjax}}\(F_c\){{/mathjax}}= Cut-off frequency of the filter. Any noise with a frequency above this will be filtered out.
128 +* {{mathjax}}\(R\){{/mathjax}}= Resistance of the resistor in low-pass filter.
129 +* {{mathjax}}\(C\){{/mathjax}}= Capacitance of the capacitor in the low-pass filter.
129 129  
130 130  Using a resistor with 1k {{mathjax}}\(\Omega\){{/mathjax}} and a capacitor with 100 **nF **in capacitance, the cut-off frequency will be 1592 **Hz.**
131 131  
... ... @@ -152,14 +152,58 @@
152 152  
153 153  where:
154 154  
155 -* {{mathjax}}\(x\){{/mathjax}} = The mechanical placement excluding the dead length (178mm).
156 -* {{mathjax}}\(V_s\){{/mathjax}} = The supply voltage of the linear potentiometer, in this case it is 3.3 {{mathjax}}\(V\){{/mathjax}}.
157 -* {{mathjax}}\(V_{out}\){{/mathjax}} = The output voltage of the linear potentiometer. ranging from 0.033{{mathjax}}\(V\){{/mathjax}} to 3.267{{mathjax}}\(V\){{/mathjax}}.
156 +* {{mathjax}}\(x\){{/mathjax}} = The mechanical placement excluding the dead length (178mm).
157 +* {{mathjax}}\(V_s\){{/mathjax}}= The supply voltage of the linear potentiometer, in this case it is 3.3 {{mathjax}}\(V\){{/mathjax}}.
158 +* {{mathjax}}\(V_{out}\){{/mathjax}} = The output voltage of the linear potentiometer. ranging from 0.033{{mathjax}}\(V\){{/mathjax}} to 3.267{{mathjax}}\(V\){{/mathjax}}.
158 158  
159 159  === Filtering ===
160 160  
161 161  The sensors output latency can be expected to be a lot shorter than the air 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 air temperature sensor acceptable with a cut-off frequency of 1591 Hz.
162 162  
163 -== Cooling Sensors ==
164 +== Gearbox Temperature Sensor ==
164 164  
165 -The cooling sensors for the AR26 can is the
166 +The gearbox Temperature Sensor for AR26 will be the [[GAG10K3976B1>>https://www.te.com/en/product-GAG10K3976B1.html]], a NTC temperature probe which will be installed into a generic M5 bolt which is mounted on the upright in the wheel assembly. The thermistor will be connected in a voltage divider configuration where the thermistor is in the lower position so that the voltage lowers when the temperature increases.
167 +
168 +[[image:Oil_Temp_schematic.png||height="208" width="486"]]
169 +
170 +Knowing the beta constant of the thermistor, the equation for the temperature based on the voltage measured by the ADC inside microcontroller can be derived.
171 +
172 +(% style="font-size: 1.5em;" %)
173 +(((
174 +{{mathjax}}
175 +$$
176 +R_T = R_f \frac{V_{out}}{V_{in} - V_{out}}
177 +$$
178 +{{/mathjax}}
179 +)))
180 +
181 +Where:
182 +
183 +* {{mathjax}}\(R_f\){{/mathjax}}= The upper resistor in the voltage divider which stays fixed, which in this case is 1k {{mathjax}}\(\Omega\){{/mathjax}}
184 +* {{mathjax}}\(V_{out}\){{/mathjax}}= The voltage over the thermistor, and the voltage that the microcontroller will measure.
185 +* {{mathjax}}\(V_{in}\){{/mathjax}}= The supply voltage of the voltage divider, which in this case is a constant 3.3 {{mathjax}}\(V\){{/mathjax}}
186 +* {{mathjax}}\(R_T\){{/mathjax}}= Resistance of the thermistor
187 +
188 +Knowing this, the resistance of the thermistor can be added into the following equation. This will determine the temperature of the thermistor based on the known resistance and the beta value of the thermistor.
189 +
190 +(% style="font-size: 1.5em;" %)
191 +(((
192 +{{mathjax}}
193 +$$
194 +T = \frac{1}{\frac{1}{T_0} + \frac{1}{\beta} \ln\left(\frac{R_T}{R_0}\right)}
195 +$$
196 +{{/mathjax}}
197 +)))
198 +
199 +where:
200 +
201 +* {{mathjax}}\(\beta\){{/mathjax}}= material constant that defines the steepness of its resistance-temperature curve between two temperature points, usually 25/85 degrees celsius. In this case it is 3976 //**K.**//
202 +* {{mathjax}}\(T_0\){{/mathjax}}= The test temperature at which the thermistor is 10k {{mathjax}}\(\Omega\){{/mathjax}}, which in this case is 25 degrees celsius.
203 +* {{mathjax}}\(R_0\){{/mathjax}}= The resistance of the thermistor when it is 25 degrees celsius.
204 +* {{mathjax}}\(R_T\){{/mathjax}}= The live resistance of the thermistor.
205 +
206 +=== Filtering ===
207 +
208 +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.
209 +
210 +
Oil_Temp_schematic.png
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