VEX problems
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orangeltr456
- Posts: 20
- Joined: Jul 5th, 2013, 10:44 am
VEX problems
So. i am using a VEX cortex micro controller ( a teacher donated a bunch of vex for me to use) this is nice because I can easily program the controls to do just about anything I want. The problem arises when I try to send the pwm signal over 150 ft of tether. All my servos start to spaz out due to interference I believe. Any way of fixing this. Or would it be easier to somehow use the vex to communicate with an arduino connected to another arduino via data link. ( i have read some things about that, not sure how to do it tho) any help would be appreciated!
Re: VEX problems
So in good trouble-shooting fashion...
The controllers behave OK at say 10', but just not at 100'+, correct? What type of wire is being used? I know in general what VEX is and their lineup but have never worked hands-on with it - does it use twisted pair for the control signal(s)? Is the normal supplied cable shielded or in some way different from your long one?
For best case interference, can you run ONLY the control signal cable over 100' without it being close to any other cable? Doesn't solve anything but could tell us the cause is not the PWM signal getting lost, but rather it being bashed by some other power or noisy cable laying next to it, etc.
Another question, but just where is the 100' tether? I assume you have joystick controller - VEX controller board - maybe speed controllers like a Jaguar - servo.
If the long cable is between speed controller and servo, I tried once to make some long extensions from a typical RC Radio receiver to the servo and they wigged out at only 12'. I don't think plain PWM is made for much distance.
There are indeed several Arduino to Arduino based layouts in construction around these forums. Search on Arduino or 485. Should be straightforward to go VEX to Arduino - long tether with RS485 or similar - 2nd Arduino - speed controllers - servo motor.
The controllers behave OK at say 10', but just not at 100'+, correct? What type of wire is being used? I know in general what VEX is and their lineup but have never worked hands-on with it - does it use twisted pair for the control signal(s)? Is the normal supplied cable shielded or in some way different from your long one?
For best case interference, can you run ONLY the control signal cable over 100' without it being close to any other cable? Doesn't solve anything but could tell us the cause is not the PWM signal getting lost, but rather it being bashed by some other power or noisy cable laying next to it, etc.
Another question, but just where is the 100' tether? I assume you have joystick controller - VEX controller board - maybe speed controllers like a Jaguar - servo.
If the long cable is between speed controller and servo, I tried once to make some long extensions from a typical RC Radio receiver to the servo and they wigged out at only 12'. I don't think plain PWM is made for much distance.
There are indeed several Arduino to Arduino based layouts in construction around these forums. Search on Arduino or 485. Should be straightforward to go VEX to Arduino - long tether with RS485 or similar - 2nd Arduino - speed controllers - servo motor.
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orangeltr456
- Posts: 20
- Joined: Jul 5th, 2013, 10:44 am
Re: VEX problems
Vex mostly uses 3 wire ( red+ black - white PWM) and yes im using a 888 motor controller, but it is all the same for servos or the 330 series motors. My goal is to have the wirless joystic controller and cortex above water and signal ran down to the motor controllers and servos,
So for the cable I am using cat5e, The PWM will power all the way down 150' But only 1 signal wire. If I add a second or 3rd they all go crazy. even if i put my hand in the coil of wire things start to make noise and move. I cut the wire down to 50' and still get the same result. right now I have 3 motor controllers L R Up 3 servos pan tilt and gripper. so i will have 6 PWM and a common ground and power + 12 gauge power wire ran.
So for the cable I am using cat5e, The PWM will power all the way down 150' But only 1 signal wire. If I add a second or 3rd they all go crazy. even if i put my hand in the coil of wire things start to make noise and move. I cut the wire down to 50' and still get the same result. right now I have 3 motor controllers L R Up 3 servos pan tilt and gripper. so i will have 6 PWM and a common ground and power + 12 gauge power wire ran.
Re: VEX problems
I would search around on the MATE site. Plenty of ROVs there are built with either VEX components, or by people who had previous experience with VEX. There is a Harmony school in Houston I know just did one, but I could not find them via search.
But my basic guess, is the Cortex needs to live on the ROV (close to the controllers/motors).
http://www.marinetech.org/tech-reports/
But my basic guess, is the Cortex needs to live on the ROV (close to the controllers/motors).
http://www.marinetech.org/tech-reports/
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orangeltr456
- Posts: 20
- Joined: Jul 5th, 2013, 10:44 am
Re: VEX problems
So the problem with the cortex on the rov is no wireless signal will go 150 feet underwater and I don't think I can extend a USB that far. Plus USB gets rid of my wireless functionality. I'm guessing my ideal way would be to interface the vex with 2 arduinos . More than I really wanted to wire up. And not knowing if it is going to really work.
Any ideas on running brushless motors in sea water . Obviously water proofing is necessary but how. I eventually want to have enough power to fight currents at 150 ft. In the Chesepeek bay. Right now I'm using 1200 gph pumps . Check out my design under the introductions topic . Titled Maryland says hi.
Any ideas on running brushless motors in sea water . Obviously water proofing is necessary but how. I eventually want to have enough power to fight currents at 150 ft. In the Chesepeek bay. Right now I'm using 1200 gph pumps . Check out my design under the introductions topic . Titled Maryland says hi.
Re: VEX problems
Never used VEX myself, but just had a look at some VEX stuff on the net. They have a UART in them. So looks like you could have the handset talking WiFi with the topside VEX, and that talking to the ROV VEX via their UARTS and the RS485 converters.
Maybe also consider using the RS485 converters to send the PWM down to the ROV. Will need 1 pair for every PWM signal
More hardware but less software and one less VEX.
Use the forum's search tool to look for corrosion motors re your salt water question. Oil-filled or magnetic couplings would be my choice
Maybe also consider using the RS485 converters to send the PWM down to the ROV. Will need 1 pair for every PWM signal
More hardware but less software and one less VEX.Use the forum's search tool to look for corrosion motors re your salt water question. Oil-filled or magnetic couplings would be my choice
Re: VEX problems
VEX microcontrollers accept input from VEX potentiometers, maybe an arduino could simulate this signal