Drive by wire functionality

[ElsmoortelG]

We had some bad experience with the ref limiter and gear change ignition cut on our rotary engine. We are not sure it broke the engine but fact is that the engine hasn't broke any more since we deactivated the systems. Maybe it is just a coincidence. To be honnest the engine calibration has been changed also since then.

I fear activating these systems again and was looking for a solution.
With an DBW system I think we are able to restore the same functionalities as before and don't have to touch the ignition-system.

I found the following functionalities in the ECU manager software and want to check if they correspond with my understanding. If not could you please correct me so I do not have false hope when I go over to the purchase.

I want to use the throttle for up-shift. So the throttle angle changes towards 0% during a predefined time to get the load of the engine. The driver keeps his foot on the accelerator pedal. Typical behavior for dog engaged transmissions. But automatically done by the ECU and triggered by a load cell in the shift lever.

I want to use the throttle for down-shifts (throttle blip). To be able to shift faster into lower gear. The blip depends on the wheelspeed and gear which it is in and triggered by a load cell in the shift lever.

This I didn't find but never the less I would like to know if it is possible :

I would like to use the throttle to perform the pit limiter function. Throttle valve works like a PID with wheelspeed as feedback channel.

I would like to use the throttle for RPM limit when the driver revs to high. The throttle valve is controled in closed loop with rpm as feedback channel.

And of course with every change in throttle position the logic needs to follow the injection and ignition which comes with this throttle position.

Somebody did this before ? And who can give me some usefull tips and hints ?

[figgie]

well I can tell you that with DBW you can incorporate Throttle Up (closing throttle) and Throttle down (blipping throttle) with the DBW.

Under the Function > Gear Shift > Up Shift DBW position/Duration or Down Shift DBW Position/Duration

The other items. That might sound out of scope as the pit limiter function won't be a DBW item as otherwise, from a logic bases, that means cruise control of course I can be wrong and there is a way to do this "cruise control" logic which would be nice for street duties but if there is, I am not aware of it.

[MarkMc]

Yes Figgie correct, you would use the Gear Shift function for your upshift "de-blip" and your down shift "blip". The strain gauge on the gear lever is the best way to do this....is it an H pattern or a sequential box? The problem on an H pattern is how do you tell the ECU if a rise or drop in force is an up or down shift.

The pit speed would not be closed loop but you should be able to make this work quite effectively through the DBW Translation table and Compensation table. This will be fairly easy if the driver stays in the one gear coming into the pits. The RPM limiter can be done in a similar way.

Just a note on the engine damage scenario (not being a rotary expert myself), some work that was done a few years ago showed the retard for the flat shift to be a problem if you went too far....resulting in broken apex seals.

[Ben-S]

For determining blip/"deblip" you can use a clutch switch, most people will use the clutch on downshifts even if it is sequential/dogbox so they dont upset the balance of the car, you can actually make the rpms follow the exact road speed based on the best gear if you use a ton of tables so even if you have the clutch in for an extended period of time you will still have a perfectly matched engine/road speed granted this isn't built into the software but its easily possible with the number of user definable maps and i have done so successfully.

[ElsmoortelG]

In our case it is a sequential transmission. So the loadcell can do the job.

I do not understand how the DBW translation table and compensation table can do the Ref limiter and pit limiter function ? There should be a condition when it has to activate a certain table. I mean for example when the pit button is pushed then the table should be activated. Could you please clarify this a bit and also how it could work for the ref limiter ?

About the down-blip. The relation between RPM, gear and speed I can figure out with I2. But how I should implement this in the ECU manager software that is not clear for the moment. You say that with the range of the user definable maps it can be easily done. I know that the X and Y axle can be changed in all graph but the graph are all related to a certain subject. I mean fuel, ignition, auxilaries or functions. I can't see where I can find a user definable table with a complete freedom like the user conditions in the ADL2.
Can you please explain this also a bit more in detail how you did this ?

Currently we have 3 throttle valves(manual) which are connected with each other. I was thinking to put one steppermotor on the axle and have them activated with one motor at the same time.
Is this possible ? Or do I have to mount 3 electrical throttle valves and expand with a DBW4 unit ?

[Ben-S]

I do not know a way to do the ref and pit limiter function though im sure it could be done. How many axis is your position translation table currently? You can use any extra aux table to effectively add a table to your DBW position translation along with using your comp table that should give you all the feedback you need to have a throttle follower for vehicle speed, by using the clutch or default gear as one axis somewhere in there you can effectively turn the vehicle speed follow "function" on and off. Like i said its not made to do this but is possible. Doing this AND trying to build in limiter functions in the same manner could get pretty complicated and might not even be possible but either on their own should be very do-able...

As for the 3 throttles on 1 axle i would think as long as the motor had enough power to turn all 3 throttles as quickly as needed it would be no different than driving a single throttle so it should definitely work.

for the motec guys, why arent the limiter and pit speed functions dbw? this seems to make the most sense...

[Apex Speed Tech]

ref limiter and gear change ignition cut on our rotary engine.

for the motec guys, why arent the limiter and pit speed functions dbw? this seems to make the most sense...

We broke cranks on our superbikes during pit lane speed limiter. If not dbw, can we have a bit more control over the cut functions? Control of cut patterns or cut % versus target error has worked really well. Also, a retard then cut function like you do with TC might be helpful.

Another thing that works for pit limiter is to set the ignition timing to a static, retarded number when the limiter is active. This takes a lot of response out of the motor and keeps the timing from moving around if the drivers is moving the throttle a lot.

[Martin]

You can use any extra aux table to effectively add a table to your DBW position translation along with using your comp table that should give you all the feedback you need to have a throttle follower for vehicle speed, by using the clutch or default gear as one axis somewhere in there you can effectively turn the vehicle speed follow "function" on and off. Like i said its not made to do this but is possible.

Hi Ben,

Im not following here but is this what you are menaing?

DBW has Positition translation, and a Comp table....if you want more tables...can you use a unused AUX output table and set it up to generate a channel? Can you feed this generated value as an input into the COMP or POSITION TRANSLATION tables?

I have looked, you would be able to feed lets say a duty cycle of an unused output into another table, do you have other means of doing it?

Regards,

Martin

[Ben-S]

This is much more difficult to explain than it is to show someone but i'm trying. Lets say you have your regular translation table already 3d and you are using your comp table... well if you want to have 2 more things effecting that channel your out of luck right? but if you use "aux 1 output" (for example) as the 2nd axis then you have another table than you can make 3d defining your 2nd axis so even though you have only added 1 axis to the control table that axis is based on two other parameters. It sounds more complicated than it is and im sure if you mess with it some you can get it working.

[Martin]

thanks, ive figured it out