Homebuilt ROVs Forum

Most of the hobby ESC's are for brushless, but you can also find them for brushed motors... but they are harder to find...

This ESCs in this thread are for brushless motors.

Thanks!

Still having start-up problems using these ESCs. Problem worse when run in water. Sometimes good other times not so good. Have trouble starting up, then remove power from ESC (control signal from micro still running into ESC input) and power up again and then suddenly much better??? One solution may be to put a big FET in circuit so ESCs can be powered up and down to achieve reset by the microcontroller. Good idea to have this anyway, no matter what sort of ESC is used.
Plenty of thrust so I will be limiting the ESC power output as was my intention and changing the micro code to automatically give a short burst of "fast" to start the motors, then drop back to desired speed. The ESC and motor combination starts up much better when given more throttle. Once moving happy to go very slow. Video link below for your entertainment http://youtu.be/RzD0jTJPu9U

Rossrov are all your ESC/motors connected to a common battery or are each on its own battery? How are you powering each ESC? Via a BEC circuit?

Thanks for questions Biker. ESCs are running off common battery. They have internal BEC for their own logic, and I am running the camera and microcontroller off a separate 2A switchmode supply (in-car USB adapter). Recently swapped the worst-behaving ESC for the spare I had, and is improvement. Seems like they are all operating on the limit of easy-starting - hence some better than others (component tolerance etc??). Possibly these particular ESCs would work OK with lower power motors or inrunners, more turns on the motor windings giving a stronger feedback to the ESC sensing inputs. Just a theory. Will eventually buy some other ESCs to see this part of the project through and maybe hack the Trackstar 18As for the FETs. What ESCs and motors are you using please? (save me going through all the posts)

Ross

Motors

http://www.rctimer.com/index.php?gOo=go ... oodsid=123

ESC's

http://www.hobbyking.com/hobbyking/stor ... verse.html


ESC programmer

http://www.hobbyking.com/hobbyking/stor ... r_ESC.html

The programmer is supper simple to use and makes setting the soft start, brake and other features a must.

Cheers. The ESCs and programmer are now on my HK shopping list. I think I've got the present setup as good as it's going to get, so planning a second salt-water test before opening the ROV up and replacing the ESCs.

rossrov wrote:Cheers. The ESCs and programmer are now on my HK shopping list. I think I've got the present setup as good as it's going to get, so planning a second salt-water test before opening the ROV up and replacing the ESCs.

Just curious but did you program your ESC's for soft start, minimal braking, high timing etc.. ?

Punch limiting disabled - high limiting made motors very slow to start. May re-try the midway settings. Again.....
Timing set to lowest, setting higher gave no improvement.
Drag brake disabled, brake amount minimum

Traditionally servo PWM signals from the receiver "refresh" 50 times per second (50 Hz, 20mS), so 50Hz is what I used to control the ESCs. Having now learnt more about the current servos, ESCs and radio control systems, it's clear that refresh rates up to 400Hz are now common. So, altered the refresh from 50 to 400Hz, and now the Trackstar 18As are working very well. Still doesn't explain why one of my 4 Trackstars worked well on both 50 and 400, possibly that one had different firmware or even a different microcontroller. Hope this helps others that may be having trouble getting reliable starts.

Cheers,

Ross