How difficult is it for the average joe to implement a 3 phase motors to work with an ardiuno and reciever for scaled down version of construction equipment? Is there any benefit to 3 phase over dc power? Maybe efficiency? To avoid all the headaches maybe better to just use stright dc power?
I'm guessing "3 Phase" is the same as what is commonly referred to as "brushless"?
Brushless motors are very common in the hobby robotics world but generally we use off the shelf ESCs to control the brushless motors. These hobby controllers are controlled with the same sort of signals used to control hobby servos.
I think larger brushless motors use different controllers but I imagine these can also be controlled without too much work using a microcontroller. I think the hard part of using a brushless motor is the driver. One can use a simple relay to control a brushed DC motor but a brushless motor requires fancy electronics which is beyond most hobbyist. If you're using a brushless controller made by someone who knows how to do this sort of stuff then I don't think there's a problem controlling it with hobbiest gear.
Russell Cameron (aka OddBot) designs robots for Dagu. He recently made some "dancing lions" which I believe used large brushless motors. I think the motor shown in this video is one of these brushless motors but I'm not sure.
These lions used to be documented on Let's Make Robots but the new owners (RobotShop) of the site deleted massive amounts of material on the site when (former) members didn't agree to the new terms of service. Russell didn't agree to the new terms so all his stuff was deleted. IMO, it's a huge loss to people wanting to make robots.
You might be able to find hints about controlling the motors on Russell's YouTube channel. Russell now posts information about his robots on RobotRebels.org. Hopefully he'll add information about controlling the large brushless motors sometime.
I'm sure there are other sources of information about controlling large brushless motors. I'd think the lack of brushes would be a big advantage in many applications. I can't see why one couldn't control large brushless motors with an Arduino provide you had the right drive circuitry.
DuaneDegn:
I'm guessing "3 Phase" is the same as what is commonly referred to as "brushless"?
A brushless DC motor (BLDC) can be 3-phase - but it doesn't have to be such; most are, though.
Typically, though, when talking about "3-phase" - you are talking about an AC motor, with 3 independent AC (sine) line level phases, spaced 120 degrees offset to each other, that power the motor.
IIRC (don't quote me here!) - typical hobby-grade BLDC motors use a 3-phase signal, but the phases are square-waves, IIRC (?) - like I said, I am probably wrong.
EDIT - hmm - sorta kinda was wrong:
http://dcacmotors.blogspot.com/2010/03/waveform-of-brushless-dc-motor.html
Brushless motors generally have a better power to weight ratio and can easily be controlled using easily obtainable ESC.
Example i have a motor 2in long and 1/12 in dia which can put out 800 watts.
If you need a reversible motor you need a reversing ESC.
They are easy to control with the servo library.
They can require a high current , so a lipo or LA is pretty much needed.
DuaneDegn:
Russell Cameron (aka OddBot) designs robots for Dagu. He recently made some "dancing lions" which I believe used large brushless motors. I think the motor shown in this video is one of these brushless motors but I'm not sure.
Thats a brush motor.
A brushless motor that size could probably drive a tank.
Or similar tracked vehicle ....... 
Also brushless motors have more torque compared to brushed and torque does not drop off like brushed motors.
Its one of the reasons dentists use electric motors these days instead of air turbines.
Its possible to build a driver on a eurocard with hobby skills but with 20 A ESC available from hobby king the size of a postage stamp its probably not worth it.
Boardburner2:
If you need a reversible motor you need a reversing ESC.
It should be possible to reverse a brushless motor with an appropriately heavy duty DPDT relay. Since switching any two of the three wires of a brushless motor will reverse its direction, a DPDT relay would make it possible to swap the wires under control of a microcontroller. I think it would certainly be a good idea to stop the motor before reversing it.
Of course an ESC which allows reversing would be a lot easier to use but I've often wanted to try the DPDT idea.
DuaneDegn:
It should be possible to reverse a brushless motor with an appropriately heavy duty DPDT relay. Since switching any two of the three wires of a brushless motor will reverse its direction, a DPDT relay would make it possible to swap the wires under control of a microcontroller. I think it would certainly be a good idea to stop the motor before reversing it.Of course an ESC which allows reversing would be a lot easier to use but I've often wanted to try the DPDT idea.
Sounds like a way to burn out an ESC - they do not fare well if only two phase wires are connected.
MarkT:
Sounds like a way to burn out an ESC - they do not fare well if only two phase wires are connected.
The third wire would be left permanently attached. The two wires connected to the relay would (hopefully) only be switched when the motor has stopped.
Theoretically there would always be three wires connected when power is applied.
Standard ESCs and RC brushless motors are designed to push propellers, and do not work at low speed.
You probably want to stick to motors and ESCs using hall-sensors for commutation, they work at
any speed and can be used to reverse direction under load.
Sensorless ESCs require a minimum rotation speed to sense the motor position for commutation, and
have to run open-loop when starting up, which is much less usable torque.