I want to build an active-aerodynamic spoiler using my Arduino Uno.
I would like to use this to sense car motion, only one axis... Under braking, I want to spoiler to go full-up for maximum downforce and braking. Under steady speed or acceleration, I want to spoiler to move to flat or no-drag position.
For position sensing, I would use this Sparkfun rotary encoder. I could also use just contacts and simple on-off, since it's only two-position, but the more elegant solution would use the Arduino brain, since I could adjust behavior with code only.
For servo/actuator, I was thinking the strongest, cheap unit would be an automotive 12V window motor. This should be strong enough with some lever advantage... Not super fast, but would probably do it.
Thoughts?? Will this be easy to do for a relative novice? (Only a few tutorial-type projects under my belt...) Anybody care to help a brudda out with some code/advice?
I would start with the mechanical stuff (servo, spoiler, etc). Then you may drive full speed and while breaking go spoiler full-up with a simple switch. When still alive I would continue with the code
Do you mean if I'm still alive or the project? I was assuming I'd do each little bit of the project and test individually as I went along. Flipping the switch while driving at 120MPH isn't something that's going to be feasible. Too many other things to worry about. I'm better at racing than at electronics...
I also thought about just making it with a spring and tying it in to the brake lights, just have the motor pull it down until the brake lights come on, then pop it up with a spring. But where would the fun in that be?
I think I'd try to implement a purely electrical solution. Make/buy an inertial switch which closes a circuit when longitudinal deceleration exceeds your threshold. Design a mechanical solution using your window lifters, wiper motor or whatever you prefer, with limit switches for the up and down positions. Design a control circuit so that deceleration caused it to be powered upward until the upper limit was reached, and when the deceleration ceased it was powered in the down direction until the lower limit was reached. I expect you should be able to achieve that using simple switches and relays.
You do also have the option of using the switches as inputs to a microcontroller and having microcontroller outputs which control power to the motor, but that's a much more complex, fragile solution.
I have got such active spoiler on my veyron, and the mechanical part seems to me 98% of the problem when I watch how it operates (it shifts in 0.4sec full). The forces are huge with my spoiler, about 300kg of downforce at 180mph, so a simple mechanical solution may not work That is high-tech..
pito:
I have got such active spoiler on my veyron, and the mechanical part seems to me 98% of the problem when I watch how it operates (it shifts in 0.4sec full). The forces are huge with my spoiler, about 300kg of downforce at 180mph, so a simple mechanical solution may not work That is high-tech..
Your Veyron? :smiley-you-cant-be-serious:
I do agree that the mechanical aspect would be the hardest part, and that OP should try to achieve that first.
IMHO the most straightforward way of introducing automatic control for the spoiler would be with a two-axis accelerometer. It will tell you when there is heavy acceleration or braking of the car (you want downforce then, right?) or when the car is making hard left/right turns. Interfacing is pretty simple if you use an analog accelerometer; not a whole lot of precision needed in an application like this.
Seriously? You have a Veyron? I'm familiar with the Veyron system, not the specifics, but I'm sure there are VERY expensive actuators involved. They probably cost more than my entire race car. This is mostly a fun project, not sure how useful it will actually be. I do like the idea of an inertial switch and not bothering with the microprocessor, and could even do some type of pneumatic, high-pressure system to create those types of speeds/forces. We are not talking about Veyron speeds (or forces) here, though. Also, it could be done mechanically in a way that the forces exerted are applied to the structure, not the actuator.
I was assuming the roll (left/right) wouldn't be important, only the longitudinal (front/back). If you're turning, you are either accelerating through a turn or have already done all of the braking. The physics of driving a race car are such that you never do any quick turning without already having done the vast majority of the braking. The car's weight swings far forward during braking, so you get a double effect from an active spoiler (I'm speculating). A drag effect, complementing braking, and a downforce effect, keeping more weight on the rear wheels and thus also complementing braking of the rear wheels. Normally, the rear wheels are only able to provide a small percentage of the braking power because of the weight shift.
You could also eventually get clever and do active yaw or left/right aero assist, similar to a rudder, on the ends of the spoiler, but I'm not doing that now.
I really think this problem be broken down into longitudunal G's >=0 flap down, G's <0, flap up. From what I can see looking at components, pure mercury-type switches will be somewhat bouncy and unreliable, unfortunately, and the accelerometer would give perhaps better results.
A drag effect, complementing braking, and a downforce effect, keeping more weight on the rear wheels and thus also complementing braking of the rear wheels.
The rear spoiler air-braking works fine with speeds over 200mph. If you copy veyron's system your spoiler shall flip into a 60% angle in 0.4secs, while creating an additional air-breaking deceleration of 0.7G. That is huge. The rear spoiler assembly costs $70k, afaik.
I think you'll want to keep the downforce through the turn. And, you really don't want the downforce turning-off suddenly in the middle of a corner when you back-off the brakes.
It would be easy to test the Arduino/accelerometer with an LED before you build the mechanical stuff, but I don't see any reason why the electronics won't work.
For developing & testing the electro-mechanical part, I'd start with a simple switch. If you want to wire it to your brakelight, that would be OK.
Airplanes use use hydraulics. I don't know how DRS in Formula 1 works, but I wouldn't be surprised if it's also hydraulic.
In most forms of auto racing, I believe a moving wing/spoiler is illegal...
Flipping the switch while driving at 120MPH isn't something that's going to be feasible.
F1 drivers have a DRS button and a KERS button, and a whole bunch of other buttons on their steering wheel!
I was assuming that since I'll be using el-cheapo motors for actuators that the turning-off will be slow and gradual, enough time for us to get through the corner.
The type of road racing I'm doing encourages this type of foolishness, so illegality won't likely be an issue.
Excellent point on the F1 steering wheels. I was thinking about a toggle on the dash. Wiring up to a removable, 720-degree-rotating steering wheel will be a trick on the cheap, though. Plus, I'm not Kimi Raikkonen!
DVDdoug:
In most forms of auto racing, I believe a moving wing/spoiler is illegal...
That's certainly true in the UK:
J5.20.10:
Any specific part of the car influencing
its aerodynamic performance must:
a) comply with rules relating to coachwork.
b) be rigidly secured to the entirely sprung part of
the vehicle.
c) remain immobile in relation to the vehicle.
I want to build an active-aerodynamic spoiler using my Arduino Uno.
I would like to use this to sense car motion, only one axis... Under braking, I want to spoiler to go full-up for maximum downforce and braking. Under steady speed or acceleration, I want to spoiler to move to flat or no-drag position.
For position sensing, I would use this Sparkfun rotary encoder. I could also use just contacts and simple on-off, since it's only two-position, but the more elegant solution would use the Arduino brain, since I could adjust behavior with code only.
For servo/actuator, I was thinking the strongest, cheap unit would be an automotive 12V window motor. This should be strong enough with some lever advantage... Not super fast, but would probably do it.
Thoughts?? Will this be easy to do for a relative novice? (Only a few tutorial-type projects under my belt...) Anybody care to help a brudda out with some code/advice?
Thanks in advance...
This is something I've been looking at doing myself and mechanically I've been looking at linear actuators that work via a potentiometer (i.e. varying resistance dictates the relative position from retracted to extended.
F1 drivers have a DRS button and a KERS button, and a whole bunch of other buttons on their steering wheel!