Looking at building an underwater ROV for maximum depth 120 feet, controls is where I am starting. I plan on having 3-4 thrusters, a camera and possibly some other devices. I am interested in the PS2 controller, (PlayStation 5A Servo Motor Controller (Kit) Product code : RB-Ima-34). So what I am thinking is, using direct burial Cat 5 cable as tether, I send video signal through one twisted pair, use on-board battery for powering thrusters and camera, use the PS2 board to actuate servos for camera position, use output from board to control speed controllers (used in RC models) for thrusters. Now the one question I have is, seems the control card has a design which works with servo positioning, however if I hook up speed controller will this work or will the system detect servo going out of range, this apparently sets off the rumble function of the controller and shuts output down to save servo.
Now another important design of the control system is the use of the Cat5 cable to transmit RF signal, my plans are to possibly hack the PS2 RF receiver on board the ROV which is connected to the circuit board then use one of the lines through CAT5 as an antenna, then topside the PS2 controler should be able to send wirelessley to the on-board circuit board. I have studied what people do on these home built ROV’s and the common control is using RC remote controls, in this same manner, using one line of CAT5 cable as antenna, makes it very simple. Any suggestions or help would be greatly appreciated.
See diagram, the video signal travels up a twisted pair, the RF signal comes from the playstation RF input module which is plugged into the playstation servo controller within the ROV, RF signal travels up one conductor, used as antenna. This is a very common method used with radio controls designed for model aircraft in homebuilt ROV’s, it keeps it cheap. The signal does not travel through the water.
Well the ps2 controller requires 7 conductors and the CAT5 has 8 conductors, leaving me short one conductor, also the controller would require a power signal from the PS2 servo card, the line being 120 feet, would this signal reach the controller, then have to be sent back, I would think it would degrade over that length, so the RF would make sense since we are not transmitting voltage just RF. I guess a small micro controller would work but then I have to learn the comunications protocols find the proper equipent then develop the controller for topside then do the hundreds of lines of programming which would allow the controller to control the rov, seems very complicated. I am open ears though if there is an easier way but my thoughts are that over 120 feet we must keep to communications protocols rather than voltage commands since they will degrade over the distances.
Okay done a lot of reading appears like the scenario I came up with someone else tried and had troubles with, not sure if they just did not know where the antenna output was on the PS2 rf module. I did however find a nice site where someone is working on the use of two arduino boards and developing software for ROV purposes, code.google.com/p/rov-suite/ a very interesting site. I think the use of the arduino’s may be the best solution as controls could be endless and the addition of inpust such as pressure and direction could be accomplished. I will do some more reading.
The 5A servo controller is certainly an option if you use a wired PS2 controller. Note that the signal can only be sent so far before you will need to amplify it once again. As you indicated, to get the length you need, a CAT 5 cable is an option. The video feed would ideally be separate. You can hook up a motor controller with R/C input to the servo controller to control DC motors. The same works with ESCs with R/C input. Not sure what you mean about the antenna.
Where does the video signal go?
That’s what I suspected. If you have the video feed going to the robot via cables, why do you need the controller to be wireless as well? It would be far more reliable if it was permanently connected. If you’re going to have the robot tethered, then try to offload as much as you can.
When the video feed reaches the surface, would it be sent wirelessly? Does that mean there’s a transmitter in the sub? Can you create a simple diagram?