Differential drive robot with bicycle front wheel hub motors?

Dear All,
I would like to build a wheeled differential drive robot based on two 28’’ bicycle front wheels with ordinary hub motors and a small free running tail wheel. The main application will be weed treatment in agriculture.

The whole system will weigh about 100kg, it is meant to run slowly (1m/s) but precisely and provide high torque. Slopes are below 20 degrees.

I have seen hub motors for mountain bikes with internal planetary gears with high torque which could do the job.

My questions:

  1. Most common bicycle hub motors have typically 250W or 500W power and a voltage of 36V to 48V. Which (dual?) electronic speed controller (esc) would be appropriate?
  2. If I decided to use worm gear motors instead, which motors would you recommend?

Thank you,

If you don’t already have the setup, consider opting for a more complete e-bike starter kit solution which includes all of the electronics:

  • Two hub motors
  • Controller
  • Battery
  • Wiring

If the battery becomes difficult to ship, get the specs of the motors and the battery. The e-bike hub motors are not designed for very slow speeds, so they might not be very efficient running as slowly as 1m/s.

In regards to a worm gear - can you explain the setup? Would you use a BLDC motor and connect it to a worm, or you’d opt for a motor + gear setup which is already together?

Can you provide a sketch of what you think it might look like?

Dear Coleman,

thank you for your answer and sorry for my late reply.

That is what I thought but I have not found and e-bike / pedelec kit with a dual controller for good synchronization.

There is a very interesting, well designed and mature commercial system available but I would like to go for much larger wheels (in diameter) to improve performance in pastures with rough texture caused by cattle trampling. It seems to me that they are using (BLDC?) motors with gears. Worm gears seem to be advantageous to me because the system would not roll on slopes while not powered.

There are hub motors with planetary gears integrated, such as in this video. I think they are used for mountain biking revealing higher torque than usual.

Another alternative might be hub motors for wheel chairs.

Just a few random examples from Alibaba:

I still would have to mount larger 28’’ rims to the motors somehow …

What about the dual channel motor driver from robotshop? Do you think I could use them with the hub motors? Aren’t the hub motors not BLDC? What about reverse rotation?

It’s rare that a DC motor cannot rotate in both directions, but good to ask if you’re not certain. You can opt for a worm gear system, and although RobotShop does not carry a wide selection of these yet, you can find them online. The controller must be suitable to the motor, so not sure about which dual channel motor driver you are referring to. The BLDC with worm gear option seems interesting in your case.