Help with engineering project
 

Hello everyone! I was wondering if anyone could help me out. I'm working on an engineering project for one of my college classes. I am building a Semi Autonomous ground vehicle that collects golf balls. Right now i'm trying to figure out the best motor to use for the build. The vehicle size is going to be 1.5ft by 2ft and im projecting it to be around 15 to 25lb max with everything onboard. I plan on using two motors at the front of the vehicle, directly connected to wheel or using a belt and motor pulley system. For turning the vehicle will be program to spin the front wheels in opposite directions. The wheels im going to use will probably be 6inch diameter with 1 1/2 in width. Which type of motor would be best for this setup? I don't need this baby going 50 or 60 mph. 10 to 25 MPH would do just fine but I don't want to buy a under powered motor either.


I've been looking at 1/5 scale motors but alot of them seem like overkill and are pretty expensive. 1/8 scale are still pricey but im not sure if they would be strong enough as i will need a lot of torque.


Does anyone have and suggestions or ideas that can help me? Unfortunately they don't teach Motors and electronics to Mechanical Engineer students hahaha Thanks!

of course they teach you motors in ME. you just need a few hints.

you know how fast you want it. look at kv ratings to determine motor speed. 1 volt = how many rpm. you know gearing and how to calculate the circumference of a wheel to determine velocity. there will be a ratio on the pinion to spur, a built in ratio to the chassis (found in a manual).

or you can find a dyno curve on here for a motor and calculate the torque you need in order to move the mass.

or you can calculate the power you need to achieve the speed and torque to do the work and as long as the math is right. take the calculate torque and rpm and put a single dot in the middle of the dyno curve and select a chassis based on that. you will lose 25-50% torque and rpm if the dyno curve is motor only and not a log from a chassis dyno.

the tough calculation is acceleration torque but if you can ballpark 2-3 times continuous torque as a limit to peak torque. or run for short bursts. or get a motor for a rc boat that can be liquid cooled and get 4-10 times continuous torque as you peak torque limit.

if you minimize rolling friction the work the motor has to do will be minimal. the acceleration will make or break the project in that case.

matching the load and power train inertia to the rotor inertia at something less than 30:1 will probably be a good starting point. just select a ratio that allows you to move up or down a little when you go to run your tests so you can tune the heat out.

most calculations are mech not electric.


https://cimg6.ibsrv.net/gimg/www.rct...a0345ed0c.jpeg
this is a trinity factor 17.5 with a final ratio of about 3.7:1 and wheel diameter of 63mm.

Just visit a robotics/battlebots shop.

I would go for a geared 775 motor

Not sure 25mph is a realistic speed for capturing balls efficiently unless your primary focus is on a new method of collecting balls. 5-10 kmh max is probably more realistic (may as well go Metric now if your going to be an engineer). 2 kmh = .5 meter per second which is about the speed of an autonomous lawn mower.

How much speed can your ball collector handle with a 100% collection rate?

+1

Banggood has a pretty good selection of battlebot parts too, another option to consider is a "Electric Skateboard" motor for under $50:
https://www.banggood.com/search/elec....html?from=nav

just an idea for you to kick around... I would be thinking to make my design scalable and adaptable... there could actually be a market for your product.. higher end golf courses could probably be persuaded to spend the money considering they wouldn't have to pay a guy $30-$60k a year to drive around in a cage which let's be honest doesn't look to classy... but a sleek robot doing the job;)... Then there is industrial lawn maintenance... potentially tons of product could spawn from your little project... Think a little more like Elon Musk or Jeff Bezos... if all you wanna do is pass your assignment just throw a couple of motors on a lawn sweeper with the brain box from an autonomous lawnmower and be done...not trying to be rude but I think you have a great idea here and I'd hate to see you waste it, just think a little bigger and long term..

Its a Job .pay aint all that bad ...its what alot of members pay for get a bucket of balls get a text from the guy you paid to tell you when ball fetcher is on range blast him lol...seen alot of guys rush over to driving range just to get a few line drives in I dont see the robot taking to many hits...

It would be nice if topicstarters would stick with one topic....

https://www.rctech.net/forum/chat-lo...l#post15684789


Beside all that, I can be wrong... but isn't is the idea that first of all school projects are based on the lessons you had? And isn't it the idea you do the project on your own or your team if there are more people and no done by others?
I know a Dutch forum where school questions are forbidden because of those reasons.

the automated golf ball gathering system has been done several ways. Ive worked with 2 or 3 startups that did it and disappeared. systems to get them from lakes or on the turf. in the end its a two part process and the most labor intensive part is not the gathering of the balls. its the sorting of good balls from bad at regular golf courses. there is more money in cleaning up a course that is not purpose built because the balls are not beater balls. dont let me discourage a perfectly good project. thats not my goal but to make it commercially sustainable it seems that doing it on a golf course is where development dollars seem to make sense.

I would consider 540 5-slot crawler motors 12 to 16 turns, simple, cheap, controllers are simple and cheap, lots of power and speed if you want it.

Heck maybe just build your rig on an existing crawler. Pre-engineered solutions for you.

You'd probably find cheaper motors outside of RC. Try finding a (mechanically) broken electric scooter, bike, golf cart, lawn mower, etc.

Another avenue to explore for parts is the powered golf pull cart market.

https://www.motogolf.com/products/Ba...4aAvHNEALw_wcB


Here's a module you can add to an existing pull cart.

http://www.intheholegolf.com/Merchan..._Code=EW-EW001

People use these in power wheels rated to carry 150 pounds of kids.

I think it has no used to help the topicstarter.

He got some reactions in the other topic and since then never came back