How do more motors effect a bots overall power? How about mixing motors?
rwgast_logicdesign
Posts: 1,464
So ive been working a ton of math to size motors wheels etc, just been doing alot of overall research about motors themselves, and how to get more power from motors. The one thing i havent been able to find out is how more motors will effect your robot. So lets say you have a 4 or 6 motor differential drive bot, all motors matching, this obviously allows for better traction but how about a bigger load than 2 motors (I would think so). If more motors means a bigger load how much does each extra motor effect the load weight or pushing force?
Also would it be feasible to use two different sets of motors in a 4wd bot, bigger ones in back smaller ones in front and just use encoders/pwm to help make the back motors run at the same speed as the front then if you get stuck or something give all 4 motors full force?
Also would it be feasible to use two different sets of motors in a 4wd bot, bigger ones in back smaller ones in front and just use encoders/pwm to help make the back motors run at the same speed as the front then if you get stuck or something give all 4 motors full force?
Comments
You could mix motors but you're going to make things way more complicated than they need to be. Why would you want to mix motors? If I were building a 4 wheel differential drive base with conventional wheels (not omni wheels) my preferred method would use on motor on each side (with matching motors) or you could used four matched motors one on each wheel. Unless you have a very specific reason for mixing motors it would be nothing but a headache. Or as some would say one big PITA.
There are so many different ways to build a motorized base and those can be sized differently depending upon the size of your finished robot. Unless you are basing your platform on known combinations that work well then you'll have to do some experimenting to determine of your motor/base combination will work. Expect some of your first attempts to not work out so well. That happens and you can learn from it. I can tell from many of your posts that you are trying to do this on a budget but keep in mind that trying to go too cheap and cut corners may end up costing you more overall. Don't fall into the trap of buying all sorts of random parts because your design keeps changing before you've gotten anything together.
You've been asking some good questions and obviously are putting a lot of thought into this which is good. Keep working on your project and you'll eventually get something together and rolling around.
For now, just try to get a base together and mobile without dealing with the encoders. Just getting the mechanics can be a challenge. Once that is working you can add encoders to help control the motors and movement better. Beyond that add sensors and have fun.
In regards to the base there are wide ranges on what people consider small, medium, and large. For small modified servo's rule. For medium the $10 DC gearmotor with wheel that I posted earlier can't be beat. They are one of the cheapest ready to use combos that works very well. I made a BAXTER robot clone (out of a trash can) with these and printed custom encoders to stick on the wheels. Power is from a single 12V 7Ah battery. For medium robots the Wheelkit that the Stingray uses work well but that will cost you a bit more. For larger robots the expense can go up dramatically. You'll probably be looking at heavy duty DC gear motors or something like the Parallax Wheel kit $300 or wheel chair motors. Larger H-bridges and motor controllers for these motors can add quite a bit of cost as well.
I figured getting 4 gear motors would be the easyiest option, but its not cheap.. then i found thos faulhaber/micromo 141:1 motors with encoders for 3 bucks it was a god send. then i realized they were really slow and small the current on these is 10% of the motors i have now. so i canceled that order.
i need enough speed to outrun a dog (not a fast one lol see my avatar) and enough torque to get across sand not rough terrain just regular desert sand some softer some hard.
the reason i ask what adding more motors does is becuase im curious if i use 4 motors what will that do for me over two? im thinking a 5lb bot based on the micromos may work at 10v (add says they do 18 review says the get hot after 10) if i had 6 of them. these are really nice motors and im ordering a pair reguardless. if this sounds to rediculous for these motors i still need to know the advantages of more motors as this will effect my final motor desicion and number of motors. electronic gm also has 6v screw driverz for 2 bicks thats a motor and planatery gearbox and a way to chuck the axels bit im afraid they will be slow as molasses
i also dont know what 10 dollar motor wheel combo your talking about i guess i missed it, but i wouldnt be able to get four right now anyway.
i need enough power for a custom prop pcb, a custom motor controller, 3 hbrige boards, a rasberry pi, some sort of camera, emic 2 speech board, two pan tilts, 6 pings, bluetooth, wifi bridge. thats just bear minimal planned electronics no batterys charging board or chasis/wheel weight. the wheels i want at the rc shop are 4inch with stubble on the rubber but for now i was gonna settle for the 4 inch 1 dollar set on electronics goldmine.
im really thinking about the 6v screw drivers but thats a Smile shoot too there is no specs not to mention idk if there built in a fashion where i can usevthe motor/gear box/chuck and trash the rest, the gears could be built into the acual screw driver casing