Bitcraze Forums

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

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.

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.

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.

Could you please start a new forum thread for your question?

Done here: viewtopic.php?t=5362

Thanks!