Hello all,
I’m planning to build an airplane capable of carrying payload under its wings (one under each wing), and considering to use PX4 to autonomously control the aircraft. A typical mission involves picking up and delivering these payloads at multiple locations, and there’s no guarantee that both the wings are equally loaded all the time. There are scenarios when there’s a payload under one wing while the other wing is free (asymmetric loading). Consequently, the CG of the aircraft moves along the lateral axis with some movement also along the longitudinal axis which causes a large rolling moment.
In this regard I have the following questions.
a) Is there a way to input the true CG location to PX4?
b) If the answer to the previous question is NO, then is it possible for PX4 to handle CG movement in flight without performance degradation.
Any input/ suggestion is appreciated.
Regards,
Shashank
Hello …
a) Is there a way to input the true CG location to PX4?
Yes you can do it
b) If the answer to the previous question is NO, then is it possible for PX4 to handle CG movement in flight without performance degradation.
Yes you can do it
To have good location and landing or to do drop off you need RTK GPS pixhawk & IR-LOCK Sensor - Pixhawk
Hi Danial,
Thank you for your response. I was looking at the parameter list and could find parameters for modifying sensor locations with reference to CG, and not find parameters specific to modifying the CG location itself. Request you to help me understand how the CG offsets/ movement needs to be taken care of.
Regards,
Shashank
hello why you need to change parameter list there is no need to change sensor parameter location you can use mission planner to do your delivery
Danial,
Let’s consider two cases -
a) CG at the geometric center of the aircraft.
b) CG to the right of geometric center due to payload only on the right wing.
In case b), the aircraft always tends to roll right. Therefore, trim values/ parameters are to calculated with the shifted CG position such that these trim values allow the aircraft to fly straight and level in spite of the CG offset. While PID loops have robustness which can account for CG movement, if there’s a way to input the possible CG locations and determine trim apriori, the performance of the attitude control loop can be greatly improved.
Regards,
Shashank
You’re better off just testing this since if the aircraft is trying to roll right whether it is heavy on the right or drag, the autopilot would simply counter this. I’d be more concerned with takeoff and landing than level flight but for the most part we’ve tested what you’re talking about and it doesn’t pose an issue unless truly extreme and in a crosswind while taking off.
