I am working on a automated rover. I plan on using a 24v 250W e-bike brushless motor with a 200amp esc and an APM/Pixhawk power module(28v/90A). Would this setup work when connected to ardupilot mega or pixhawk. Can you guys suggest a better method.
Just one motor? The ESC is overkill for that size motor. Make sure the ESC has over current limit. If you are only driving the one motor and the ESC has over current limit, the 90A power power module should suffice, as full load current would be about 10A.
If using more than one motor or an ESC that will not do current limiting, then get a better power module, such as a Mauch unit, at least 100A. The resistor based 90A power modules can only handle real high currents for an extremely shrt period of time. The MAUCH hall effect power modules can take their rated current continuously - your wires would melt first since they would be undersized.
Also ditch the mega. Go for a Pixhawk, or better a Cube. You will be able to run the latest code with the latest features.
Thanks for the reply! I plan on using one motor which has a planatery gear drive.
This is the esc which I plan to use:
Would I be able to control a 36v 250W bldc with the same setup.should I use a vsec then?
Go with the VESC - much superior motor controller. Not cheap but supposed to be good. Have not used one.
The Red Brick ESC has no over current protection, and you will only be able to go forward with it (without upgrading the firmware on it if possible.)
With the VESC the 90A power module will suffice provided you set the over current protection properly in the VESC.
What motors are you looking at using?
Currently my larger rover is using four 24V 450W brushed gear motors for electric bicycle conversions (MY1018-1 motor/gearbox) with two 60A 2x60A roboclaw motor controllers (each motor driven separately.) Modified the motors to add an encoder for feedback to the motor controllers. Ready to run on R/C and getting the parts together to add a cube and ArduRover to it.
Going to 36V will require going to a MAUCH power module.
What are the advantages of using brushed motors overs brushless. I have to drive my rover over rice fields. So I require lots of torque. Is the whole setup with brushed DC motors cheaper and simpler to connect with ardupilot
The motor which I am planning to use:
Sorry for so many questions I am a total beginner in this area.
This is a hub motor. It is meant to replace the hub on a bicycle wheel. Do you plan to use it in this way? A rover with a single driven wheel? I guess you will have serious traction problems, if you do it like this.
Brushed motors are much easier to use in a robot application. They only require two wires and can be connected in parallel, controlled by only one brushed ESC. There are very good brushed robot ESCs available, like the sabertooth or roboclaw series. And brushed motors do offer a better slow turning and start from a standstill behaviour then brushless motors, without additional sensors and wires.
I was planning on using a belt drive but I guess I am over complicating things. Thanks for the tip. I will look into brushed motors.
There are plenty of brushed motors for electric scooters from 100W to 1000W on ebay etc. They have either beltdiscs or chain sprockets for 25H (#25, thin chain)
or T8F (thick) rollerchains. Belt drives, even timing belts need very high tension to keep them from slipping/jumping. Chain drives are easier to build and you can cut the chain to the length you need. There are a few things to keep in mind when building a chain drive, like using sprockets where the number of teeth are not dividable, so that the same roller does not hit the same tooth everytime. For slow rovers/robots or low loads it does not matter that much, but the mechanical construction needs to be sturdy enough and you need a method to adjust the tension of the chain.
There is no right or wrong when it comes to brushed vs brushless motors. Brushed tend to be lower in cost.
HobbyKing has some very powerful brushless motors (outrunners), but still require some form of speed reduction to be useful. A brushless motor with encoder feedback to a good motor controller will provide plenty of low end torque.
A 250W motor may not move much if on rough terrain or if the vehicle has any weight unless geared way down in speed.
There are no easy off the shelf solutions unless you are using a known frame/drive train were somebody else did all the work to figure out what works/does not work… Expect to do a lot of experimenting with different drive train setups.
I use both brushed and brushless motors on different devices. It all depends what I can find that works for me and the application.
Thanks for the tips. I have decided to go with pmdc 24v 250w brushless motor with abt 20Nm of torque. I will use a sabertooth 2x32A motor driver and pixhawk.
However i am not able to find how to connect motor driver to pixhawk. Also which type of steering would work the best in muddy terrain. I am planning to use it in rice fields.
Aren’t ricefields flooded most of the time?
The drivetrain is going to suffer if used under water or in mud. Not to speak of the electronics, but they are easier to protect than moving mechanical parts.
Skid steering is much simpler to do than ackermann steering if you are building the chassis yourself. Skid steering also has less moving parts, so it should be more robust.