Adding motor drive to generate downward thrust

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zhanghaijason
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Joined: Fri Jul 28, 2017 9:07 pm

Adding motor drive to generate downward thrust

Post by zhanghaijason »

Hello,
I am wondering if downward thrust can be generated if I add motor drives to control the four motors. Thanks
tobias
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Location: Sweden

Re: Adding motor drive to generate downward thrust

Post by tobias »

It depends on what you mean. There are two possible solutions.
1. Reverse the direction of drive of the propeller. This requires a H-bridge driver which the Crazyflie does not have. Would be possible to build on a expansion deck though.
2. Using variable pitch propellers (as on helicopters). I have not seen any design that is small enough for the Crazyflie. It would also require new drive since both the propeller speed and pitch needs to be controlled.
zhanghaijason
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Joined: Fri Jul 28, 2017 9:07 pm

Re: Adding motor drive to generate downward thrust

Post by zhanghaijason »

tobias wrote: Mon Nov 12, 2018 12:32 pm It depends on what you mean. There are two possible solutions.
1. Reverse the direction of drive of the propeller. This requires a H-bridge driver which the Crazyflie does not have. Would be possible to build on a expansion deck though.
2. Using variable pitch propellers (as on helicopters). I have not seen any design that is small enough for the Crazyflie. It would also require new drive since both the propeller speed and pitch needs to be controlled.

I guess H-bridge would be the solution since most of the time, upward thrust is used for normal flight and downward thrust is needed not very often.
dastonge
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Re: Adding motor drive to generate downward thrust

Post by dastonge »

Hello!

We also have a small research project going on for which we'll need to get bidirectionnal control of our Crazyflies motors. We managed to do it, for larger models, using the ESC+Bolt setup, but we now want to control the tiny Crazyflie motors with a dedicated custom deck. We plan to populate our deck with 4 H-bridges, such as https://www.digikey.ca/en/products/deta ... R/15286883. We will hook them to the PWM signals (as it is done on the BigQuad deck https://github.com/bitcraze/hardware/bl ... rev-c1.pdf), and several digital pins (ideally 2 are required for each H-bridge to get sleep and brake features). Do you have any other recommendation on the H-bridge chip or does anyone have tried this before?

Our current options for the digital inputs are:
- get 4 available digital outputs from the CF expansion pinout to control the Hbridge direction (forward and reverse have opposite signal - we lose the brake and sleep features);
- add an I2C chip to manage all of the H-bridges inputs;
- use different PWM frequencies for forward and reverse and detect the frequency change on our deck to swap the H-bridge control inputs.

Note that we also plan on using the flow deck v2 with z-ranging and maybe the LPS deck too....

Thank you for your support,
David.
kimberly
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Re: Adding motor drive to generate downward thrust

Post by kimberly »

Could you please start a new forum thread for your question?
dastonge
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Re: Adding motor drive to generate downward thrust

Post by dastonge »

kristoffer
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Re: Adding motor drive to generate downward thrust

Post by kristoffer »

Thanks!
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