Launch Control: Input Configuration
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Input Configuration
03.31
| 00:00 | As always, the first step is to ensure that the inputs are correctly configured and calibrated properly. |
| 00:06 | In its simplest form, we can utilize a single wheel speed sensor on an undriven wheel, and a sensor on the tail shaft or gearbox output shaft to measure driven wheel speed. |
| 00:18 | While you could fit a single speed sensor to a driven wheel, this can give control problems if the differential allows a single wheel to spin independently of the other. |
| 00:29 | Fitting the speed sensor to the tail shaft or gearbox output shaft, on the other hand, will allow the wheel spin to be detected without using a sensor on each wheel. |
| 00:39 | The best option, however, would be to have a wheel speed sensor on each wheel allowing wheel slip to be detected with maximum accuracy. |
| 00:48 | When setting up a wheel speed sensor, you do need to be aware of the ECU's requirements. |
| 00:54 | Many factory wheel speed sensors particularly those used for factory ABS systems, will use a reluctor or magnetic sensor, and many ECUs will require a digital, or hall sensor input for wheel speed. |
| 01:08 | If you're in this situation, there are modules available from the likes of MoTeC that can convert a reluctor signal into a digital signal. |
| 01:17 | While I'm discussing ABS systems, there are a couple more considerations if you're looking at using existing wheel speed sensors for an input to your ECU. |
| 01:27 | Due to the required resolution, ABS sensors typically have a very high tooth count. |
| 01:33 | While this might seem ideal, it can end up being problematic. |
| 01:38 | The issue is that at even moderate road speeds the frequency can become too high for some ECUs to read effectively limiting the range of speed the ECU can see. |
| 01:49 | Or course, you can reduce the tooth count on the sensor to provide a lower number of evenly spaced teeth to fix this problem, but it pays to find out what the frequency limit for your particular ECU is before you go too far. |
| 02:03 | The other issue that should go without saying is that you shouldn't try sharing the wheel speed signals with a factory fitted ABS system. |
| 02:11 | This may affect the ability of the ABS system to do its job correctly and hence the safety of the vehicle. |
| 02:18 | Using the ABS wheel speed inputs is only viable if the factory ABS system is no longer in use. |
| 02:25 | In many cases now with modern cars, we have the benefit of being able to read wheel speeds directly from the ABS computer via CAN which cuts our costs as we don't need any specific hardware to do the job. |
| 02:38 | Regardless how we're getting the wheel speed data into the ECU, it's important to spend the time and ensure the calibration is accurate. |
| 02:47 | Depending on the ECU's capability, we may also choose to add a switch or a multi-position rotary switch to allow some control over the launch system from the cockpit. |
| 02:59 | Launch control requirements can vary as the track conditions change so it's useful to have the ability to make these changes without needing the laptop. |
| 03:09 | This could be as simple as a switch to turn the launch control on or off, or perhaps a wet versus dry setting, or alternatively you can use a multi-position switch to incrementally adjust the launch control. |
| 03:23 | Once we've configured and tested the outputs, we can move on to setting up the actual launch control. |
