Advice on best motors for small robot

Using Arduino Motors, Mechanics, Power and CNC
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Hi

I am relatively new to the world of Arduino but very new to the world of steppers and continuous servos. I am trying to build a small 4 wheeled robot that has decent torque so it will be able to climb over soil and mud in gardens etc.

The first attempt was made using Stepper motors which were great to control, but got very hot and had a high current drainage.

I decided to try continuous rotation servos/motors and chose the FS5106R servos. I have tried controlling directly from the Arduino board (with a seperate power supply and common earth) and also using the PCA9865 but whatever I try to do, I can not get a consistent rotation speed between the wheels.

  1. Am I barking up the wrong tree try to use Continuous roattion servos for this job? They seem to stay cool, have good torque and low power drain.

  2. If I am wrong, what should I use? If steppers, how to you keep them cool or does that not matter?

  3. If I should use the FS5106R's or equivalents, how can I get them all to turn at the same speed in either the same direction or, as two are facing the other way, two forward and two backward all at the same speed?

Pearls of wisdon greatfully received.

Andrew

2

Continuous rotation servos are nice for some applications and less so for others.
Accurate speed control is not one of their features.
Forward, stop and reverse are all doable. And some level of speed control is likely available. But because you are using servo electronics which are designed for quick positional movements, accurate speed control is often not going to happen.
If the mechanical gearbox and motor fits your requirements, you might consider removing the servo electronics and replacing with a proper H-bridge.
You also might consider adding encoders so you can monitor the actual movement of the wheels and adjust the speed on the fly.

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