How To's

Control Options
These are just some of the various control options you can use for an Rov, there are many more options available these are just some of the ones I have used or looked into.
The most basic option available is to used simple switches with a pair of wires going to each thruster. To achieve Forward and Reverse of the thrusters you need to use a 3 Position 6 Pole Center Off type switch, I like to use a Momentary Flip Switch type so when you release the switch the motor will turn off.
The above drawing shows the crossover hookup which allows for the forward/reverse of the thruster. Using plain switches is probably the easiest and cheapest method of control but it does have its draw backs. You only have basic on/off control (no speed control) and each thruster requires 2 wires in the tether multiply that by the number of thrusters and this means a thicker tether. The longer the tether the thicker the wire needed because of line loss or voltage drop, you could compensate with more power but I'm not going to get into the particulars of that. Overall this set up is good for shorter tethers.
This is a Vellman K8023 10 Channel 2 Wire Remote Control Kit. This kit allows you to control 10 channels over just 2 wires at long distance. (I've tested this setup up to 300' and have heard of guys pushing it to 1000') Using this kit will greatly thin out your tether, power would still have to be sent over the tether but with only 2 wires for control the power wires could be thicker. (Another option would be to run on board batteries.) Inputs can be switches, push buttons, or open collector outputs from another device.
Older Arcade Joysticks are a good option for inputs on the K8023, they usually have 4 simple push button switches inside. You can use 2 sticks and set them up like a tank, push both forward would turn on 2 thrusters to go forward, one up, one down would make you turn ect. ect.
I like to use one joystick for steerage and the other for depth control. I set one joystick up so its mounted 45 degrees off center, this way pushing forward turns 2 switches at once which still turns on 2 thrusters at once. Left (in the case of the Seafox Rov) would be strafe left and Diagonals are turn left and right.
The downsides are its still only basic on/off control and the kit only has 10 channels. For forward/reverse of 3 thrusters that would use 6 of those channels and you will need to run relays. This drawing shows a simple hook up of 2 relays to handle forward and reverse. The relays I used were DPDT type.
This is a great little relay I like to use for a lot of project requiring forward and reverse. This relay consists of two 225 ohm coils and two sets of contacts, this makes for an easy hook up and a smaller package then using two separate relays. Here is the Data Spec sheet for this relay it can be purchased from the Electronics Goldmine Item Number : G14951
Interface boards are another option, This one is a Phidgets USB interface board which I am experimenting with for my new Rov. There are several makers and variety of boards, some have digital, analog, and PWM functions it all depends on the Manufacturer. This one is only digital so its still only basic on/off control but it does have inputs. Some of these boards are serial and some are USB. This one is a USB type so I have to use USB extenders to control it over the tether. To run an interface board also requires a computer with means a laptop for in the field use, they also require you to write your own custom software.

You can see my HBR Design 3 Page for more info on this
Another option I looked into but haven't tried myself yet is Serial Servo Controllers. This one is a popular one, it is a Mini SSC II and can be controlled by any computer with serial-output capability, such as Laptop or even Parallax BASIC Stamps. They can control standard R/C servos and speed controllers which allows for full analog control, again you will have to write your own software. The downside to using these are the speed controllers can be expensive. 3 thrusters = 3 speed controllers. I was thinking of trying one of these and using one speed controller to set the speed of all the thrusters and then using servo switches to turn them on and off but I'm not really sure if that would work and my budget doesn't allow it yet.
There are other options out there such as Basic Stamps, Vex Controllers, ect. but I don't have much experience with any of them so I can't really get into them yet maybe in the future.
If you have any other questions I didn't cover feel free to E-mail me.
©2008 - Steve Thone