Go Down

Topic: Fix altitude motor controller (Read 375 times) previous topic - next topic

aneikei

Is there any way to use a pressure sensor or another form of altitude sensor to feed into an Arduino to control the output of a 12v DC motor? Basically, turning the Arduino into an autopilot to control the power output of a motor providing lift for a drone.

I want to automatically control the drone for an indoor display to have it hover at a set height.

Thank you in advance.

hammy

#1
Sep 16, 2020, 02:38 pm Last Edit: Sep 16, 2020, 02:42 pm by hammy
The problem is the change in pressure  verses altitude is small .

You could try a "vario" method where once you are at the altitude you want , any change in output from a low pressure sensor is used . For example if you have a low pressure differential pressure sensor connected to a small volume with a pin hole in it , when altitude changes you will see an instant pressure change on one port of the transducer and a delayed change on the other .

Google vario for some more ideas , but you still might struggle , maybe ultra sonic distance measurement to the ground might do it ?

Paul_KD7HB

#2
Sep 16, 2020, 06:13 pm Last Edit: Sep 16, 2020, 06:14 pm by Paul_KD7HB
Is there any way to use a pressure sensor or another form of altitude sensor to feed into an Arduino to control the output of a 12v DC motor? Basically, turning the Arduino into an autopilot to control the power output of a motor providing lift for a drone.

I want to automatically control the drone for an indoor display to have it hover at a set height.

Thank you in advance.
In my former business, we had a customer with a product that supplied and controlled oxygen for the pilot in light aircraft. They used a barometer chip, made in Korea, that could detect an altitude change of 5 ft. Would this be enough for your project? You would need to design a circuit board yourself, if you want to use the device.

Paul

PS. Checking the air pressure DOES NOT indicate altitude above a floor!

aneikei

Hi thanks for replying, yes a barometer chip might indeed work. Can you send me any information on it and how to find it online?


Paul_KD7HB

Hi thanks for replying, yes a barometer chip might indeed work. Can you send me any information on it and how to find it online?
You need to imagine the air in the room where you operate your device. While it is running, the air above the device is slightly vacuum because of the propellers. The air under the device is compressed for the same reason. Don't you imagine this will upset your use of a barometer for sensing air pressure in a room?

The air pressure will change with the speed of the propellers.

Paul

MarkT

Actually no, the moving air below the props is at a lower pressure too, due to the Bernoulli effect - moving air
always has lower pressure than the stationary ambient air in an open system.  There are pressure differences immediately around
each prop blade that contribute to lift, but much of this lift comes from momentum exchange due to the air
flow being deflected by the blades, not from the Bernoulli effect due to wing shape. (old textbooks are often incorrect on this, and can't explain why an aircraft can be flown upside down, for instance.)

The sensor just needs to be in the centre of the quadcopter to avoid any such influence.

[ If you want the real-deal on aerodynamic lift, here's a good link: http://www3.eng.cam.ac.uk/outreach/Project-resources/Wind-turbine/howwingswork.pdf ]
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

Go Up