Hi Peter, I'm sorry if we are over-complicating things for you - its in our nature to come up with unique solutions and improve on whatever we are working on.

Although I can see the reason for keeping the electronics as simple as possible, using an Arduino or other micro controller (MCU) will likely be simpler than just trying to do it with relays. By having each input (buttons & switches) and each output (the actuators) monitored & controlled separately by the Arduino, you get more flexibility to fix problems and get the system working the way you intended. Even without all those accelerometers and encoders, an MCU is still the best solution.

Looking over your posts, you have eight inputs: three switches per actuator, brakes and a button. There could be one or two outputs and I would advise two so you can control each actuator separately to overcome any speed/position differences. As well as these basics, I'd recommend one or two extra outputs to give the driver some feedback - he would definitely want to know if the wing was stuck in brake mode! The system only has three states. That is a really easy situation for an MCU and would be handled by a small logic table, which we can work out for you if you are not sure about it. You mentioned safety was a big issue and an MCU can help by monitoring and reporting faults (maybe just a failure light on the dashboard).

Those actuators might not be what you expected. Looking at the specs, the 31mm/sec speed is with no load. From experience and reading other spec. sheets, the actual speed at about half it's rated load with be much slower. Have a search for higher-end actuators and you will often find graphs showing their speed VS load - its pretty disappointing sometimes! If you look at the GLA4000 actuator, it mentions a 40% speed reduction at full load and it probably has a much higher gear reduction than the GLA750s. I'd expect the GLA750s to slow down by a larger percentage under load.

Actuators usually state a duty cycle rating and its often quite low. If the wing is moving frequently, you might find the actuators overheat.

The 550 motors may not be reliable under heavy loads and they are definitely not weatherproof, so the trunk will need to be. They could also be a fire hazard as the brushes produce a lot of sparks and the open cans will allow fuel vapour in. The type of sealed motor on the GLA4000 is what you probably need. I realise the GLA4000 doesn't meet your other requirements, but that construction style and IP65 environment rating is the way to go.

After looking at the drawings and your comments, I have a couple of questions:

What part of the car are the wing supports mounted to; the trunk lid or the body?

You mentioned up to 2000N force. Is that the total on the wing or on the point where the actuators attach? This is a class 3 lever arrangement and if the 2000N is considered to be applied on the trailing edge of the wing, you will need considerably more force to elevate the wing into brake mode. I know nothing about aerodynamics, thought I'd better ask.

Are you up for some mechanical work? Would modifying an actuator to get what you want be possible?

What about the electronics work? Could you solder a few components together of do you need everything to be plug & play?