I'm trying to write a simple quadcopter simulation. It doesn't need to be 100% accurately simulated and I don't intend to write an actual drone controller, it's just supposed to "look" right in the simulation, and I'm trying to get a better understanding of PIDs. As such, I don't need to worry about sensors, or an accelerometer or gyroscope, I get all of the information from the simulation directly.
I'm new to quadcopter physics and PIDs, so there are a few things I'm a bit unclear on. I'm not asking for concrete solutions, I'd just like to know if my ideas go in the right direction and/or if I'm missing anything.
1)
Let's say the quadcopter has the world coordinates Q(0 -50 0) (y-axis being the up-axis) and I want it to fly to O(0 0 0). The velocity I need is O -Q, so I need to accelerate the drone until I reach that velocity (Correcting it every simulation tick). To do that, I need a PID, with the setpoint being the desired velocity O -Q, and the process variable being the current velocity of the drone (both on the y-axis), and 1/4th of the PID output is then applied as force to each rotor (Let's ignore the RPM of the rotors and assume I can just apply force directly). Is that correct?
2)
The drone is at the world coordinates Q(0 0 0) and should fly to P(100 0 100). It also has the orientation (p(itch)=0, y(aw)=0 and r(oll)=0). I want the drone to fly to point P, without changing its yaw-orientation. How would I calculate the target pitch- and roll-angles I need? I can work with euler angles and quaternions (not sure if I need to worry about gimbal lock in this case), I just need to know what formulas I need. Of course I also want to make sure the drone doesn't overturn itself.
3)
I want to change the drone's orientation from (p=0, y=0, r=0) to (p=20, y=0 r=0) (With positive pitch pointing downwards). To do so, I'd have to increase the force that is being applied by the front rotors, and/or decrease the force of the back rotors. I can use a PID to calculate the angular velocity I need for the drone (similar as in 1) ), but how do I get from there to the required forces on each rotor?
4)
Am I correct in assuming that I need 6 PIDs in total, 3 for the angular axes and 3 for the linear axes?
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