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Comment by throwaway892238 | Hacker News Reader

Dumb question, kind of unrelated: In the process of building a remote controlled cart to haul small heavy loads offroad. Have no experience in engineering or robotics. Where could one go to learn what's needed, say, starting at the motor/drivetrain? (ex: what kind of motor to use, exterior or interior gearing, how to calculate motor size/voltage/gearing needed to haul X weight up Y gradient, steering geometry, actuators for remote steering, etc)

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The engineering process is always the same.

First, quantify your requirements. How much torque needs to be delivered at the wheel/ground interface, in order to get your maximum load over an arbitrary obstacle like a stone or a tree root, uphill on your maximum rated grade?

That requirement will tell you whether you can source a motor (based on the torque it's rated to deliver) or whether you need to buy a drivetrain or (RIP your budget) design a custom drivetrain.

Accounting for the weight of the motor/drivetrain will require you to iterate on that first requirement. Welcome to the pain of engineering design.

I recommend starting by looking through vendor's websites. At the end of the day if you aren't going to be fabricating your own custom motor and gearbox, you'll have to pick something out of a catalogue anyway, so check what's available and for what price. That will help you get a sense of what's possible, and then you can check that against what you want to accomplish and go back and forth until you've narrowed down something for a prototype.

Ardurover discourse and Endless sphere could be worth checking out. I've built a Ardurover rig many years ago for a bit of fun (https://agmapsonline.wordpress.com/2013/06/18/autonomous-veh...)

I have fun researching building something bigger in my spare time.

Echo much of the replies, but you have the answer in your question. Find the guy/gal nearby with a laith and some machining tools that loves the same stuff the build it, break it, figure out why it broke, if your both still working on it after iterations of brokenness its probably working out, at worst your learning and enjoying it along the way.

Robot ethics: https://en.wikipedia.org/wiki/Robot_ethics

Workplace robotic safety > Hazards, Hazards controls: https://en.wikipedia.org/wiki/Workplace_robotics_safety :

> There are four types of accidents that can occur with robots: impact or collision accidents, crushing and trapping accidents, mechanical part accidents, and other accidents [...]

> There are seven sources of hazards that are associated with human interaction with robots and machines: human errors, control errors, unauthorized access, mechanical failures, environmental sources, power systems, and improper installation.

LEGO Boost Creative Toolbox has a short mandatory safety lesson in the app.

What's a good robotics safety program?

Pybricks documentation: https://docs.pybricks.com/en/latest/

"I Put 44 Mechanisms In 1 LEGO® Machine..." https://youtube.com/watch?v=ykIYP4z-eMk&si=1hh8KvoRxCVamH4y

"Lego Technic Gearing Ratio Calculator Tool" https://youtube.com/watch?v=yUcNnj5NClY&si=hKB-b1pB3HuVM6ed

ROS2 docs > Tutorial https://docs.ros.org/en/iron/Tutorials.html

ROS Industrial Training > Session 1 - ROS Concepts and Fundamentals (ROS2) https://industrial-training-master.readthedocs.io/en/latest/...

MoveIt2: https://moveit.picknik.ai/main/index.html https://github.com/azalutsky/MoveIt2Docker

RoboStack > Jupyterlab-ROS, Jupyter ROS https://robostack.github.io/JupyterRos.html

Define "small heavy loads". How small is small in terms of volume? How heavy is heavy in terms of density?

I'm curious too how about some arbitrary requirements. it'd be fun (maybe useful?) to be able to pack in a cooler or a couple tires so let's say..

it should be able to carry a 0.5 m^3 cube and 70kg. maybe optimize for low cost and the ability to roll over some sporadic large cobble?

E-bike parts. Seems like a good application of something like a Bafang BBS02 (or knockoff) + thumb throttle. Chain drive, plug in a thumb throttle. Could instead use a hub motor, but their starting torque isn't great. Either way, you save having to re-invent the wheel in terms of motor control electronics integration.

geared hub motors are a start, but it's hard to find ones with large enough gearing for the torque of a load going up a steep incline (not to mention roots, mud, etc). a few companies sell powered wheelbarrow geared hubs with much higher internal gear ratios. but i need to figure out what the maximum force required is for a given load at a given grade and then figure out how to determine if a motor can provide that; and whether a custom drivetrain will be needed or if i can cannibalize a bike or other drivetrain (and how to tell if it's capable of handling the load). like someone else mentioned, i didn't think about adding the weight of the vehicle into the calculations

What I suggested is a mid-drive motor, not a geared hub motor. Can then size the drive and driven sprockets to whatever reduction meets the requirements of the build.

minimum specs: working load 300lbs, size about 4ftx4ftx4ft. that would carry 1 large adult person, and is the minimum weight for a wheelbarrow full of soil. (a load of soil can be up to 500lbs; for contractors, a wheelbarrow can carry up to 660lbs or 60 cubic feet of concrete. aware of powered wheelbarrows, want this to be remote controlled)

https://makezine.com/projects/lawnbot400/

My buddy was featured on the cover of make Magazine for building a remote controlled mower he put a wheelbarrow on and turned into a remote controlled lawnmower plus dump cart

You wont be hauling anything in a remote controlled buggy, if it was feasible military would be all over this.

Buy a used Quad instead.

How come ? We have drone that can follow you while keeping the camera on you, without any big issues. And that for a very low price. I thought we already got "autonomous" cart, following employees around stocks. So why not a remote buggy ?

Trained humans are better at carrying small loads reliably.

Wheeled recon bots are a thing, and have been back during the second Iraq war, IIRC.

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