PDM Installation & Configuration: Auto Engine Disable in Pits
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Auto Engine Disable in Pits
03.35
| 00:00 | - Race engineers are great strategists and they'll be looking for more than one thing to happen in the pits at a time in order to reduce the number of pitstops required overall. |
| 00:10 | For this reason, it'd be very uncommon for a driver swap to take place and the wheels not to also be removed from the vehicle for a tyre and brake pad change. |
| 00:18 | Because of this, we can be pretty certain that if a driver swap is taking place, the air jacks will be deployed. |
| 00:24 | The flipside of this is that we don't want the air jacks being deployed to be the sole determinant of disabling the engine as there will be plenty of situations where these might be down but we still want the engine running, thus the other factors in the equation, the driver's door being open and the steering wheel being removed. |
| 00:42 | This is a reasonably simple function to visualise as it's just an "and" function, the inputs to which being the 3 elements we've discussed previously. |
| 00:50 | Where the complexity comes in is how we're going to have the output of this "and" function disable the engine. |
| 00:56 | This will depend on the vehicle in question but for this example, we'll set it up so that if this "and" function evaluates to true, that is all 3 inputs are active simultaneously, the output channel driving the fuel pump will be disabled. |
| 01:10 | There will already be some logic in the overall system being used to determine when the fuel pumps should be powered so we're going to put another "and" function in there that will join that existing logic and our new engine disable logic. |
| 01:23 | To do this we'll have to invert the output of our 3 input "and" function using a "not" function. |
| 01:29 | This will mean that when all 3 of our input conditions are met, the "and" function linking the 2 logic sections together will see faults on one of its inputs, turning the fuel pumps off. |
| 01:41 | It would also be critically important that there is a clear indication somewhere in the car that the engine is disabled by this function. |
| 01:49 | If the vehicle has a dash logger installed that isn't mounted to the steering wheel because we've removed that, this would be the logical place to flash up that warning. |
| 01:57 | Otherwise, an indicator light on the keypad or a standalone light with a clear label could be used. |
| 02:04 | The signal used to drive this light would be taken from the output of the 3 input "and" function but before that "not" function. |
| 02:12 | It could be sent out physically over a wire but more likely would be contained in a CAN message packet, then being read by the dash logger, keypad or the device controlling that indicator light. |
| 02:23 | Throughout this advanced function case study section of the course, we've looked at how a PMU could be used to implement some more advanced logic than simply switching things on and off, to make our cars easier to use and safer. |
| 02:36 | We've not talked about any specific PMU platforms but instead have shown a way of thinking about how to design these functions that will let you implement them with the minimum about of debugging down the line. |
| 02:49 | Experience certainly plays a role when developing these functions and you'll find as you get more familiar with a particular PMU's capabilities and configuration software, that familiarity will drive a lot of your thinking around how to get the functionality that you desire. |
| 03:04 | This is why you'll find people wanting to stick with a PMU they've used in the past. |
| 03:08 | I've certainly been caught out assuming a PMU I've been asked to use will support some specific feature present in another that I'm actually more familiar with and have had to rethink my approach when that was the case. |
| 03:21 | This is why I strongly suggest that you read through the documentation thoroughly for any particular PMU you're considering using and get up to speed with its configuration software before making a purchase. |
