Discussion About TCS & launch control inputs
Collecting ideas. Please give generously!
- there are 8 free 12-bit AD inputs. However they must be connected to connectors, only very few are by default
- I have D connector headers on one of my VEMS units to allow access to the additional inputs.
- Not sure how many "pure" digital signals are available.
Required Inputs - controls
- Launch control on/off switch
- Traction control on/off switch
- Cruise control on/off switch ?? (option)
- Clutch switch (used for shift cut AND launch control?)
- Brake switch (possibly useful for TCS) (option)
Required Inputs - sensors
- Speedo input for Launch ctrl (Not required if we have 4 wheel speed sensors!!)
- Wheel speed sensors x4 (from tone wheels and VR sensors)
- It would be nicest if these could be a frequency input.
- Max frequency will be (very) approximately given by 50Hz*teeth_on_wheel. (for a 4 tooth wheel you nearly get 1mph per Hz)
- This may not be easy (or indeed possible) with a Genboard 3.3
- Option is to use a LM2917 f to V converter on an external board... This can then be A to D converted and an allowance made for the no. of teeth on the wheels in software. Messy, but passable.
- May be worth considering complete TCS daughterboard with single wire/CAN interface to pass "actions" to ECU?
MembersPage/GoranJurkovic/ writes: I was thinking of making piggyback MembersPage/GoranJurkovic/DaewooLaNOS/GoingVEMS/BoardComputer for TCS, launch control, BC, based on AVR, that could be connected as daughterboard to VEMS over SPI... It would measure wheels speed over ABS sensors and deliver this information to VEMS, or calculate everything itself, and just send some usefull info to VEMS like ignition retard and fuelcut...
What would be the best/easiest option?
- Rev limiter lamp - lights when you hit either main rev limit or Launch control imposed limit.
- Tacho (already well documented)
- Stuff on LCD about what's going on...
- I'm assuming the on/off switches are illuminated by themselves so don't require output from VEMS.
Launch control is currently (if I understand correctly) a "simple" rev limit imposed if an input signal to VEMS is pulled low. (On my new genboard this seems to be a permanant feature - no additional inputs connected)
It would be nice to have an on/off button and either a clutch switch or speedo signal to control it. These can be series connected, although the clutch switch would be useful for shift cut. And it would be nice to have lauch ctrl and shift cut to be separately switchable and for there to only be ONE clutch switch on the car.
Needs to read the values of the 4 speed sensors and decide what is slipping. On a 2WD (eg assumes RWD) car the following may work:
1. Under straight line acceleration, the rear wheels can spin faster than the fronts, so miss some ignition or injection events/retard the timing or something when this happens...
2. Under braking - ie when the brake switch is on - do nothing as you might upset the car's balance. (Same for under decel fuel cut - obviously)
3. Round corners - check left to right "slip" and if it's LESS than a threshold then apply rule 1. Again, the car shouldn't be upset.
When skipping events, there should be a pattern that allows the missed event to precess round the engine cylinders, so in the case of a 4,6,8 cylinder engine the pattern should be based on an odd number. (eg every 7th, 5th, 3rd event)
Needs some more refinement to make it safe!! Please add your thoughts.
Fuel cut, ignition retard, ignition cut etc. already implemented
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