Active Spoiler

Hi all,
I am totally new to this so I appologise for my lack of knowledge.
I am wanting a solution to a small automotive project that I am working on.

I am making an active spoiler for a car resto project. An active spoiler is a small rear wing that goes up and down according to the speed of the car.

I have 2 hinges from a Chrysler Crossfire that I am using. I was thinking of using 2 stepper motors with an 8mm shaft that will have to run in sync( Makeblock 57BYG Stepper Motor SKU: MB81057 ) on each side. I’m guessing I need and Arduino Thingy of some sort, and a GPS speed sensor.
The function i’d like is as follows. Start car, the spoiler opens about 25mm. As the car gets to 60km it should open approx 60%. At 100km it should open 100%. When stopping, it should close to it’s 25mm position. Also a manual over ride allowing it to be fully opened or closed.
Am I on the right track?
My question is, Will the stepper motors hold their position? Which components would you suggest?
The weight if the wing is only 2 KGs. The down force shouldn’t be that much.
Your help will be greatly appreciated.

Hi Carl,

With regards to the mechanical design, that’s something that you’ll need to experiment and test with. It’s very hard to work out exactly what you’d need as it’s so specific to your application. I’d recommend building the mechanism, and testing out how much force is required to bring it up and down.

As for the electronics, all you’d need to do is connect your Arduino up to a stepper motor driver board, then write your program to receive the speed data via your sensor, and adjust the stepper motor position accordingly.

Here are our maker favourite stepper motor drivers:

Thanks Sam.
I’ve been reading a little more on the stepper motors and some people are saying that if more torque is needed it may be better to use servos. Will a stepper hold its position? When the mechanical hinge is fully open, it has a detent and will lock in position but not in the halfway position.
Also, as for the electronics, can you give me a link to a GPS speed sensor as there are so many? Which Arduino board do you recommend? Is this the driver that will run 2 motors?

Thanks for your help. I will send a mockup of the mechanics soon.


Either one could be used, it all just depends on how you gear the mechanism. Pretty much any Arduino board will do the job, it’d be best starting off with a Uno if this is your first Arduino project as it’s the most common board with a ton of community content out there for it. Here are the components I would recommend:

As for the motor driver, there isn’t much point choosing a motor driver before you have the motor. So you need to decide which way you’ll go with that. My advice would be to use stepper motors with high reduction gearing, as it’ll probably still end up being cheaper than an appropriately spec’d servo motor.