Autonomous Helicopter Project

[codyspraker]

Currently I am part way through designing a helicopter that can perform basic tasks such as maintaining level flight without a user. To do this, I took apart the controller that was used to pilot the helicopter and did some tinkering with the potentiometers to see if I would be able to send voltage signals from my micro controller to the potentiometer pins as if I were piloting it. I have successful had my code send pulses to the rc controller where the potentiometer used to be and have the helicopter respond to the commands. However, like the original potentiometers purpose was supposed to do, my microcontrollers changing voltage is not causing the helicopter to change speed. The original voltage that when through the potentiometer was 5 volts. The potentiometer would then act as a variable resistor to the that 5v causing a change that could be interpreted by the controller and sent to the helicopter in the form of motor speed instructions. To mimic this I bypassed the potentiometer and tried to send my own signal between 0 and 5 volts hoping that any value I send to the signal pin between these two values would result in a corrosponding power signal to be sent to the helicopter's motor. However the helicopter always spins at the same speed regardless of the voltage I put through the signal pin on the controller. Does anyone have any suggestions for why it might be doing this? Or possibly any other solutions to the problem? Thanks for any help!

[Soeren]

Hi,

[...] To mimic this I bypassed the potentiometer and tried to send my own signal between 0 and 5 volts hoping that any value I send to the signal pin between these two values would result in a corrosponding power signal to be sent to the helicopter's motor. However the helicopter always spins at the same speed regardless of the voltage I put through the signal pin on the controller.

I guess that you generated the signal by PWM and forgot to integrate it coming from the controller, so, instead of a varying DC level, you just send the raw PWM pulse train (which, with just a little circuit capacitance will be peaked to close to 5V, no matter the duty cycle)?

You could test it by an external variable supply (be careful not to go over 5V!) and wires of the same length that you used with the controller. I guess it will work, but if not, the wires either picks up noise (making the receiver ignore those pulses), or have too much inductance (twist the wires, or at least let them run close in parallel).


For autonomous flight and with the controller interfacing the transmitter, you'd need another transmitter (in the chopper), to return sensor data to close the loop, but it would be better placing the controller on-board, saving you the extra transmitter and receiver.