I have completed a build of a Tarot 650 Ironman, but during initial test flights, I'm experiencing random twitches and surges from the motors. I've asked for help on this and the DIY Drone forums with no advice. I've reflashed the flight controller, redid all the calibrations, including the ESCs but nothing has helped. I was about to give up and just hang the aircraft on the wall, when I decided to make one more attempt at fixing the problem.
I have pretty much taken the aircraft apart and done a careful visual inspection of all solder joints and bullet connectors. I touched up two solder joints on the MATEK power distribution board I'm using and I've decided to replace all of the ESC lines going to the motor - I've mounted the ESCs underneath the center chassis plate in order to minimize switching effects to the ESCs on the battery side). The reason for replacing the wires on the motor side is I want to twist them to see if there are any unwanted RF effects that might be responsible for the behavior I'm seeing and if twisting the wires will help.
I've searched elsewhere about doing this but haven't found any definitive comments that this helps. So, I'm asking if any of you have any comments/suggestions.
Should definitely help. And here's a great article on electromagnetic interference and how to properly go about reducing it. It's important to note that it's not just about twisting your wires, but how to do it properly.
In an electric model, the possibility of the electric power system interfering with the radio control system has been greatly reduced by improvements in receiver technology in the last decade. However, interference can still happen, especially if care is not taken in installing both systems...
I finally put the aircraft back together - replaced a bullet connector on two motors that had questionable solder connections. I also lengthened the ESC/motor leads and twisted them. I took it out for a short flight and the problem persists - now I suspect an ESC synch issue. I am going to replace the ESCs with T-Motor AIR 40A EScs - I will be able to flash firmware and change parameters if necessary
So, I replaced the ESC's with some T-Motor AIR 40A ESCs that I found at a reduced price on ebay. I flew the Tarot and found that the surge problem seemed to be better but the aircraft would not maintain altitude during either Loiter or Alt Hold flight modes. A check of the dataflash logs showed BARO-0, BARO-1 errors, so thinking that I have a faulty barometric sensor, I ordered a new APM flight controller - 2.8. After it arrived, I decided to open up the two controllers, and discovered that the 2.6 controller I was using had no covering material over the sensor which is sensitive to wind and light, while the 2.8 controller has a small piece of dark sponge material.
So, I installed the APM 2.8 on the Tarot but when I tried to do the compass calibration, I was getting "Bad GPS" warnings. After doing some searching on the internet for APM 2.8 pinouts, I discovered that the pinouts on the 2.8 seem to be reversed. I guess I was feeding power to the GPS ground pin and vice versa. Thinking that I've damaged my GPS module, I've ordered a new on, but will have to measure the polarity of the pins before I plug it in.
So aggravating! Why can't manufacturers maintain the same interfaces???? The Pixhawk has a six pin port for GPS while the older APMs have 5 pin ports, even though both only have four wires, power, Tx, Rx, and Gnd.
Well, after all the technical issues I finally had two successful test flights! I resolved the Bad GPS warning problem - I had to plug the GPS into a port below the compass port.
I also programmed the ESCs for Intermediate Timing, which seemed to resolve my motor surge issues.
The first test flight was short - just exercised the flight controls and exercised the GPS/compass by putting it in Loiter - all went well. The second flight was a simple waypoint mission that lasted only three minutes or so, but it gave me confidence that all is working. Click here.
This will be my last post on this subject. I have had several successful test flights and today I flew a waypoint mission - a little over three minute flight but it was flawless. I don't know if twisting the wires did anything, but the aircraft seems to fly well. Here is a video of today's flight Click here.