Testing H bridge on bench with out snorkel

[nextelbuddy]

I would like a way way to successfully test the H bridge on the bench without having to have a snorkel mainly because I don't have one anymore.

For the flap control there is flap power and then there's flap positioning basically a tps sensor.

Is it safe to assume that even if you don't have the snorkel with the flap, you could wire up a TPS sensor. This way the DME sees the flap control position sensor and as long as it sees it, it will send power to the flap motor.

Wondering if I should just purchase a stand-alone flap motor from eBay like I did last time and wire that up with a TPS sensor

But I'm pretty sure you'll get a error message if the flap motor gets power, but the flat position doesn't change because it doesn't have the flap in place.

Just spitballing or seeing what other people are doing to test H bridge on a bench without the snorkel.

I would love just to be able to use a voltmeter and test flap power output whenever I run the flap actuator test in tool32. I assume it's getting 12 volts on output/trigger?

[heinzboehmer]

Wondering if I should just purchase a stand-alone flap motor from eBay like I did last time and wire that up with a TPS sensor

I would do this or build a quick circuit to mimic the motor/TPS behavior. Essentially just a load that looks like the motor to the DME and an active portion that behaves like the TPS would in relation to motor input.

I don't know exactly how the DME controls the flap, but an oscilloscope should answer that question quickly.

[karter16]

I don't know exactly how the DME controls the flap.

With a lot more code than you might expect for something seemingly straightforward lol. I haven't figured it all out yet but will post on it when I do. Looking at what the outcome is with an oscilloscope will definitely be the quickest way to find out.

[heinzboehmer]

With a lot more code than you might expect for something seemingly straightforward lol. I haven't figured it all out yet but will post on it when I do. Looking at what the outcome is with an oscilloscope will definitely be the quickest way to find out.

Any idea what the basic control strategy is like? Is the motor spring loaded and the DME outputs a voltage, then uses the TPS for positional feedback? Or something entirely different?

[karter16]

Any idea what the basic control strategy is like? Is the motor spring loaded and the DME outputs a voltage, then uses the TPS for positional feedback? Or something entirely different?

With the caveat that I haven't figured it all out yet and what I say here is subject to change based on what more I learn...

• It appears that the motor is not spring loaded/does not have a default return to zero.
• It appears that during PDR (pre-drive routine) the flap goes through an adaption process where the motor forces the flap open, and max position is measured by the potentiometer. Then closes and min position is measured.
• This appears to then be used to inform a software controller (can't say yet whether it's PID, etc.). It has a bunch of logic built in to give the flap a big kick when it starts moving, and then the motor starts actively slowing down as it approaches the learned max position. and vice versa for closing.
• There's a bunch of hysteresis logic, a stack of diag/error logic, etc. From memory (without the disassembly in front of me) it's in the order of 30-40 functions in total which makes it one of the larger modules in the software.

[heinzboehmer]

With the caveat that I haven't figured it all out yet and what I say here is subject to change based on what more I learn...

• It appears that the motor is not spring loaded/does not have a default return to zero.
• It appears that during PDR (pre-drive routine) the flap goes through an adaption process where the motor forces the flap open, and max position is measured by the potentiometer. Then closes and min position is measured.
• This appears to then be used to inform a software controller (can't say yet whether it's PID, etc.). It has a bunch of logic built in to give the flap a big kick when it starts moving, and then the motor starts actively slowing down as it approaches the learned max position. and vice versa for closing.
• There's a bunch of hysteresis logic, a stack of diag/error logic, etc. From memory (without the disassembly in front of me) it's in the order of 30-40 functions in total which makes it one of the larger modules in the software.

Wow, that's significantly more complicated than I expected. Thanks for the info!

Kinda crazy to pour so much engineering time into a component that is effectively an on/off switch.