Whats up, my name is Will. Im 25 and live in Huntsville, Alabama, engineering capital of the US. Im doing a project for a couple of mechanical engineers that work for Boeing, and this one is going to be tough. I'm doing the design side using software called Pro Engineer, or Creo elements Wildfire 5.0. For those of you who aren't familiar with this particular software, it is in my eyes the best 3-D design software on the market. I wont go into it but users have endless possibilities to design anything and everything to a "T". So here's the project - short sweet and simple. I have to design a "go kartish" size vehicle that has 4 brushless motors from scratch. Yes, you guessed it, one brushless motor per wheel. Now I've never been into go karts that much, and don't know much about the way a brushless motor works, but have 2 close friends who are FREAKS over RC cars and have 5000 dollars a piece invested in RC cars and know what they are talking about. My problem seems to lie in the controllers. I would love some input on how to design this go kart with a brushless motor per wheel, frame and everything included for discussion. I appreciate it very much. Hope to here from some of you guys soon!!
I'm new with a hard project ahead...help!
- Thread starter Addictlon
- Start date
- Status
the-cyborg
New member
This ain't gonna end up on a future episode of Rocket City Rednecks is it ?
FlatFootRacing
Speed Freak
To run four electric motors to each wheel you may want to look into a 4 wheel independent suspension type design. using cv axles and coupling them to the motors you will be able to have a steerable vehicle! what type of servo system are you looking into?
FlatFootRacing
Speed Freak
Look into four wheel drive four wheelers they use the type of suspension I am refering to.
AndI would look at electric golf karts for inspiration for control systems for the drive motors!
AndI would look at electric golf karts for inspiration for control systems for the drive motors!
Doc Sprocket
*********
Umm, FlatFoot... Why is suspension needed for steerability?
If y'all don't mind- I'm going to move this over to the Electric forum, you'll attract more (related) help over there.
If y'all don't mind- I'm going to move this over to the Electric forum, you'll attract more (related) help over there.
No, it won't haha thats funny you've seen the show.
Flatfoot, the servo system I have no clue about....like i said, im doing the design part of the project so as of the hardware being used im not sure. I just need help with what will and will not work. I found a video here of a guy putting 3 big brushless motors on a go kart. Let me know what you think about this. http://www.youtube.com/watch?v=vwODx028_Jw
Need more info. Budget, performance requirements, available tools, etc.
How about adapting a hub motor like this one:
http://www.ebay.com/itm/Brushless-H...ltDomain_0&hash=item35b847e26c#ht_5014wt_1116
Four of those would be roughly equivalent to a golf cart in terms of power.
Buy why are you starting off with requiring 4 brushless motors to begin with? Seems kind of arbitrary. Is there some kind of performance requirement driving this?
How about adapting a hub motor like this one:
http://www.ebay.com/itm/Brushless-H...ltDomain_0&hash=item35b847e26c#ht_5014wt_1116
Four of those would be roughly equivalent to a golf cart in terms of power.
Buy why are you starting off with requiring 4 brushless motors to begin with? Seems kind of arbitrary. Is there some kind of performance requirement driving this?
jman231994
New member
I dont have much knowledge of this and you may already know, but you might want to look into using some sort of microprocessor to control individual speed controllers for each motor. Set the microprocessor up so that it controls the power distribution in order to create an effect similar to what a differential does in a car. This way you will probably increase the efficiency and get better tyre wear.
Also I have heard of some electric concept cars using a brushless motor per wheel so that could be a place to check out aswell. The motors could be mounted into the wheel hubs themselves to eliminate the need for cv shafts altogether. And if it may be of interest how self propelled lawn mowers drive the wheels, the axle turns a gear that meshes with the toothed inner edge of the wheel, this gives a gear reduction in a very small space and may be perfect for what you're attempting.
Keep us all updated on how this goes. It sounds awesome
Also I have heard of some electric concept cars using a brushless motor per wheel so that could be a place to check out aswell. The motors could be mounted into the wheel hubs themselves to eliminate the need for cv shafts altogether. And if it may be of interest how self propelled lawn mowers drive the wheels, the axle turns a gear that meshes with the toothed inner edge of the wheel, this gives a gear reduction in a very small space and may be perfect for what you're attempting.
Keep us all updated on how this goes. It sounds awesome
FlatFootRacing
Speed Freak
Because you will need to use a cv style joint to be able to steer with a motor atached. I guess you wouldnt have to have 4 wheel suspension....but the steering knuckles are readily available for them and would make for a much nicer ride!
If you use hub motors then you don't need CV joints or even a transmission. The motor is integrated into the wheel so all you need to run is power. If you really must go with a 4 motor design driving 4 wheels then i think that this is definitely the way to go. I still don't get why you need to go this way though. A conventional setup with single motor driving the rear wheels would probably be much cheaper for nearly the same performance. Only reason I can think of to go with hub motors is efficiency.
FlatFootRacing
Speed Freak
The hub motor s are a good idea too! Didnt think of that one!
Doc Sprocket
*********
That's funny- 'cause I was ASSUMING that's what was being used! (Now you see why I couldn't understand your suspension/steering comment?)
I would think that you could just give each motor it's own controller and then split the throttle signal to each one. Do they need to communicate together to know what each wheel is doing?
These controllers are "fairly" basic. They take a single DC input, split it to three switching ICs, and then pulse those ICs so that it simulates a variable 3-phase electrical circuit. To add complication, you can monitor feedback from the motor to get an idea of it's RPM and load and can adjust power based on that.
Many of the newer home appliances are switching to these types of motors because they are more efficient. Even with the process of converting 120 V ac (single phase) to ~170 V DC to the variable 3 phase circuit.
These controllers are "fairly" basic. They take a single DC input, split it to three switching ICs, and then pulse those ICs so that it simulates a variable 3-phase electrical circuit. To add complication, you can monitor feedback from the motor to get an idea of it's RPM and load and can adjust power based on that.
Many of the newer home appliances are switching to these types of motors because they are more efficient. Even with the process of converting 120 V ac (single phase) to ~170 V DC to the variable 3 phase circuit.
If you use brushless motors then each motor will need it's own controller. Each controller has to know the position of the motor to commutate the windings. But hub motors can be made with brushed motors so there's no reason that they can all run off the same controller. Some brushless hub motors have integrated controllers so all you need to run is power and throttle position.
Powersupplyguy
New member
torque mode
It will be easier to run torque mode. Gas pedal is actually controlling torque in an auto. Just keep in mind if one wheel loses traction, the controller will try to drive it to infinate speed. Just limit the frequency differential between all 4 motors.
Basically you just need to control the current in a DC motor in order to control the torque. Torque is the cross (or is it dot) product of the armature current and the magnetic field. So if you use the same torque command to drive each of the 4 motors then you will have very nice performance. Going around corners will be awsum with the right rubber.
regards,
Powersupplyguy
It will be easier to run torque mode. Gas pedal is actually controlling torque in an auto. Just keep in mind if one wheel loses traction, the controller will try to drive it to infinate speed. Just limit the frequency differential between all 4 motors.
Basically you just need to control the current in a DC motor in order to control the torque. Torque is the cross (or is it dot) product of the armature current and the magnetic field. So if you use the same torque command to drive each of the 4 motors then you will have very nice performance. Going around corners will be awsum with the right rubber.
regards,
Powersupplyguy
osso12
Kartman
- Status