Which Motor to use

Hello,

I am building a 3DOF system and am baffled on which motors to use.

I will be using the sabertooth 2x60 controllers.

I want to build a platform that has a weight capacity of about 500kg, I know the weight depends on many other things aswell but how many Nm would I need on the motor I choose?

Many thanks
Mitch

Hi Mitch!
500kg + inertia induced by movments acceleration give big efforts!
Maybe you should have a look on asynchronous AC gearmotors (seen on Racingfr.com)
DC motors will have very high Starting current... that may damage your Hbridges...

Hello thanks for the reply.

I am using Ians BFF plans based on DC system unfortunately.

The motor on the plans is a 9.3Nm motor and their platform is rated for 130KG.

So by using simple maths I assume a motor with 75Nm of torque would be more than sufficient? Or does it not work like that LOL!

If you are using a design with BFF plans, is there a recommend motor to use?
Usually Ian designs a complete setup with suggested motors.
What design and do you have a sketch you can show us?
Don't toss the 12v idea in the bin yet. Let's see a design of what you would like to build.

Hello,

Yep the reccomended motor is a UNITE motor which is no longer sold

So while looking for a replacement i want to get something that can handle a bigger load.

Do you think a 50Nm 350W motor from motiondynamics would be sufficient? The reccomeded one is 9.3Nm of torque but i wish to increase the load capacity?


Many thanks

As I dont know what sim you are building and I am not familiar with the design,I dont know what sort of motor will actually do it.
Do you have a sketch of the design in mind? What load capacity did Ian specify with his original design?
Do you know, or can you find the specs of the UNITE motor.
If the specs shop 9.3NM, then yes a 50Nm motor should be fine.
We need to see a sketch of the sim. Ian designed several.

Platform rated to 130KG

I plan to use a universal steering joint mounted on top of a suspension strut instead of Ians bungee cord system. Along with a full steel welded design.

The UNITE specs (Used in platform above)
- 12v
- 200W
- 9.3Nm torque
- 203 RPM with 17:1 worm gearhead. ( Ian uses additional gearing which you can see above that reduces the RPM to around 68)


MotionDynamics Motor Specs (Which I plan to use)
- 12V
- 320W
- 50Nm Torque (Or 75 If required with 40RPM? Can just gear up to 68RPM)
- Worm gearhead producing 64RPM

So the million dollar question is, do you think using the 50Nm torque motor along with the strengthened platform design will add an extra 300kg of load capacity?

I know that question cant be answered without testing & maths etc but people would have an idea from previous experiences?

Thanks

I thought the bungee system is used to counter the weight shift in roll and pitch and helps to to keep the inertia in control and not stress the motors out. Yes without doing proper calcs, I can not recommend you removing the cords, they are in this system for a reason, they are needed.
Plus I think they also help the motors to return the platform back to its centre plus at those low rpms it will only be suited for flight as per its actual design.
Ian put a lot of time and research into these systems , its why they work well. I wouldn't change them.
I personally would find an equivalent and build the frame from light steels to lessen the platform weight so you can put a little more weight on it, save in upper platform weight will be equivalent to being able to put a little more on top it.

Not sure if you will get it to 500kg that's half a metric ton or half a small car.