I'm currently building an autonomous UAV. I've been having issues with PID control and I've tried to increase the frequency of my control loop as I thought that would be the source of my problems.
I can get my control loop and sensors to operate in the 200Hz+ region. However, the electronic speed controllers I have (pentium/plush 18A) have an update frequency of 50Hz. Is this too slow? I've been trying to flash them and reprogram them to work in the 400Hz region but that may be too difficult to accomplish.
Would a 50Hz update frequency on my ESCs doom my UAV in terms of stability?
ESC's should handle it no problem. I have tested cheap ones to 650 Hz. It's older analog servos that can't handle high update rates. I think Arducopter runs at 400 Hz to the ecs's, not a problem.
You're saying I can operate my ESCs at higher frequencies without reflashing them?
I suppose I should reiterate my question. I've been sending a 50Hz PWM signal to my ESCs but that means I can only update my ESC 50 times a second. I'm using the Turnigy Pentium/Plus 18A ESC.
I tried reflashing them to support higher speeds.
1) Is a 50Hz update speed of my motors too slow for a reasonable PID loop?
2) Can I increase my PWM frequency without reflashing?
Some/most ESC's are auto-ranging, which means that they can adjust their frequencies to match whatever reciever they're connected to.
Standard PWM have a 1 to 2ms positive voltage and the rest zero'ed out. Look up "Turbo PWM" for more infos.