Creating a hover mode

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Magnus357
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Joined: Wed Feb 06, 2013 9:08 pm

Creating a hover mode

Post by Magnus357 » Wed Feb 06, 2013 9:32 pm

Hello,

Great to see you created a forum as I think this will be a great resource for the development community.

I just pre-ordered the 10 DOF model. I haven't done any embedded programing since college, but inertial stability and navigation has always been an interest of mine.

Something I would be interested in implementing would be a hover mode. This would be a mode that, when enabled, would altitude hold. An extension of this mode would be that any altitude changes made would hold the copter at the altitude achieved when control input returns to zero. I did some looking at the barometer (MS5611) and it appears that the resolution of that unit would be sufficient for hover at approximately 500 Hz. I have similar concerns to the team that buffeting from the rotors will create some issues with resolution/accuracy.

I'm most interested in indoor relatively low height flight. I'm thinking about integrating an ultrasonic range finder unit such as http://www.robotshop.com/productinfo.as ... lang=en-US. This unit has an amazing resolution of 4cm (claimed) up to 6m which would be plenty for indoor flight.

I guess my general question would be on a scale of 1 to 10, with 1 being trivial and 10 being as difficult as developing the stability algorithm, what is your gut feel amount implementing a hover mode with a sensor that provides effective real time altitude? I did a significant amount of embedded C coding in college, but I left the EE track once I hit the real world. I'm sure it's like riding a bike though. . .

Hogosha
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Re: Creating a hover mode

Post by Hogosha » Thu Feb 07, 2013 3:03 pm

Hey Magnus357,

I also thought about exactly these Features and I'm at a similar situation related to my programing skills.
I also ordered the 10 DOF model.

Another idea of mine was to implement a signal-lost-rescue-mode. When the hover-function is implemented, the quadrocopter could hover at a Position in air as long as the Signal is gone.
This would make it much more safely. But I think this would not be that easy, because it will claim much firmware-manipulation and that will not be that easy to do...

Hope to see some more respone here in this forum when the delivery comes closer and hope to here more information about this idea by you and other users.

Magnus357
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Re: Creating a hover mode

Post by Magnus357 » Fri Feb 08, 2013 2:56 pm

I found Arducopter online, which is an Arduino power IMU system.

They use open source code as well and have a fairly advanced altitude-hold mode. They actually use an IMU IC of the similar family as the Crazyflie. Hopefully, adapting the altitude-hold wont be overly difficult.

shnytzl
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Re: Creating a hover mode

Post by shnytzl » Mon Feb 11, 2013 7:58 pm

Hogosha wrote:(...)Another idea of mine was to implement a signal-lost-rescue-mode. When the hover-function is implemented, the quadrocopter could hover at a Position in air as long as the Signal is gone.
This would make it much more safely.(...).
I was just thinking about exactly the same, some kind of "Deadman Switch" when the connection is lost. I thought a little bit further: What about a deadmanswitch, that not only holds position when the connection is lost, but also "undoes" the last actions. Practically spoken: It flies back the route it came from, or at least a few meters, in the hope the regain the lost signal. With the accelerometer this could be done by "restoring" the actual accelerations, but with negative sign.

Just some thoughts, I just thought it's funny that some people obviously think about the same things independently.

Greetings
Marc

Indieflow
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Re: Creating a hover mode

Post by Indieflow » Tue Feb 12, 2013 9:45 pm

shnytzl wrote:
Hogosha wrote:(...)Another idea of mine was to implement a signal-lost-rescue-mode. When the hover-function is implemented, the quadrocopter could hover at a Position in air as long as the Signal is gone.
This would make it much more safely.(...).
I was just thinking about exactly the same, some kind of "Deadman Switch" when the connection is lost. I thought a little bit further: What about a deadmanswitch, that not only holds position when the connection is lost, but also "undoes" the last actions. Practically spoken: It flies back the route it came from, or at least a few meters, in the hope the regain the lost signal. With the accelerometer this could be done by "restoring" the actual accelerations, but with negative sign.

Just some thoughts, I just thought it's funny that some people obviously think about the same things independently.

Greetings
Marc
This is really interesting to read! Though to go one further what about adding GPS to better hold position in the hover, also giving the dead man switch a home position (reset at turn on position) to return to if signal lost!

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