"Nissan 370z synchrorev" with an arduino

Hi There!
I tryed to post this last night but I got an error because of an url I inserted and lost all the thread, only today I got the pacience to write it again :wink:

I’m sure lots of car lovers will find this interesting.

Ok, so the thing I’m looking into is to build a device that does the same as the 370z Synchrorev. Basically what id does is when you downshift on the manual transmission, the system matches the revs so that when you release the clutch the engine is already at the desired rpm. It an automatic “heel and toe” shifting :smiley:

The programing is fairely basic, and the only inputs/outputs are:

  • A sensor for the clutch pedal (so it can know when the clutch is engaged)
  • Sensors on the gear level base (so it can know which gear is engaged)
  • Taping the speed sensor on the car (knowing the current speed)
  • Installing a servo to pull the accelerator cable (to increase/decrease the engine rpm)

The calculations involved would be just to look at the current speed and calculate the desired rpm for the selected gear. The the servo gets the engine to that rpm.

What do you think? :slight_smile:

Sorry if this was not the best place to post this…
Btw- first post, and I still don’t have an arduino :stuck_out_tongue:

Link for a video of the synchorev working:

Cheers!

Sorry for my post not being informative and on topic, but I just want to say, that if you pull this up I will personally make sure that those Arduino bashers at avrfreaks.net will apologize in public here. They have this thing about Arduino guys:
http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=87838&postdays=0&postorder=asc&sid=564a39edce276b9f3e435d83793d809f

And on topic - have you researched some PID algorithms? There is a nice PID library for the Arduino…

Well, I’m going with arduino because a friend as shown it to be and it seemed simple enough for me :wink: Also hack a day site has LOTS of projects using this, and I’m not talking about flashing lights, real world usefull stuff :smiley:

I was not thinking about programming anything too complex… but, as soon as the hardware is installed anything is possible! :smiley:

Sidenote: You don’t mention what car you intend to mod, but cars made in the last 5-10 years lack totally an “accelerator cable”. They have a full drive-by-wire acceleration. The “gas” pedal drives a potentiometer, which in turn is read by the car’s ECU.
Don’t know if you know that but if you don’t you have to do some research on your particular car…

Anyway - modifying a car without the knowledge to do it might get you, or worse - others, injured or killed.

The car has a cable :wink:
By-wire systems would be much dificult to do this, some have a cable as a backup system though.

Anyway, the level of cable pull by the servo would be very small (I’d say about 20% of the total acelerator travel). You don’t need much power to make the engine rev when desengaged.

Is danger envolved? Of course, it’s a car, and a diy system is controling the friggin’ accelerator! :wink:
(If skynet becomes a reality I’m doomed for sure!)

Edit: I’ve just remembered, I can test the whole thing on my Logitech G25. It has everything I need, gear selector and clutch sensors, I just have to take a speed reading from the simulator (this can be done in LFS racing simulator), and install the servo on the accelerator.

G25:
http://www.gamespot.com/users/MorkkiTH/show_blog_entry.php?topic_id=m-100-25314490

LFS simulator:

Drive by wire certainly wouldn’t be difficult. It would just need some investigation of the voltage range produced when pushing the accelerator. This made even easier as this data is available via the EOBD socket and a laptop. One slight fly in the ointment is that there 2 sensors in the pedal mech. The outputs are compared by the ECU and if the vary too much the car throws an error code and goes into limp home mode for safety. It would only be a case of ensuring both sides get the modified signal however. By far the hardest part of your project will be reading the current gear… Perhaps it would be possible to just use a generic blip for all shifts?

I would use 6-7(depending on how many gears the car have) hall sensors, mounted around the gear lever(under the gaitor).
And if the car has DBW(Drive by wire) the gas pedal potentiometer would most likely be 5 volt, so its sends a voltage to the ECU, thats from 5v to about 1v, acording to how much the throttle is engaged.
If you connect it over the DBW system, then you can make it find the “right” rpm, both on up and down shifting.
There are 2 ways, of finding out what rpm the engine needs to rev to, either by knowing the ratio on the gears, or by having a “map” hardcoded in to the arduino(This can actually be recorded by the arduino if you lets say is in 4 gear 2000 rpm push a button on the arduino, changes to 3, and keep the speed in 3 gear, push the button again, to let the arduino know when to “record” the data.)
By having these numbers, you can calculate the ratio.
If your car have cruise control, then it will allready have a clutch sensor, and also most likely DBW.
If the car dont have cruise control, then you can easily add it, because you allready have all the sensors.

Hmm, that was a lot of info, well just ask if you need some more info, i work as a auto mechanics.

I also though about that generic blip, that would be a much simpler idea, the problem is the system needs a way to know when to do it, this is, when downshifting…

I though about putting 2 sensors only, one in the brake and other on the clutch pedal.
The blip would happen only if both where pressed, and in a specific order, first brake and then clutch. (I’m thinking on the braking and downshift when aproaching a corner on the track)
Problem is that it would blip when stopping on a red light too… :stuck_out_tongue:

It could be done by checking the current speed, and only bliping when the speed is above a certain value…

Zeecue: I didn’t think about the cruise control… all the hardware for synchorev do the CC as well. Nice idea! :wink:
Also the hall sensors should be easyer to install then the simple switches I was thinking about…

btw- my car as a cable operated throttle