Looking for help with a school project, don't understand ESCs
02-10-2011, 08:20 PM
#1
Looking for help with a school project, don't understand ESCs
I'm in science olympiad and I'm trying to make a remote controlled sumo bot. I figured there would be some smart people on this forum website to help me.
The sumo bot that I'm building, i figured, would be pretty similar to an r/c car, but it's going to be moving a lot slower and it only two minutes of runtime. I did a little research with the motors, but not much. I'm looking at the 550 hpi gt motor since it seems to be the strongest motor I could find that fit in the competition restrictions of 14.4 v. The part that really confuses me though is the ESC. I have no idea which one I would need for this motor. Googled some but all of the ones that i saw were really expensive... except for one. I was hoping someone could tell me if it would work with it. I also know that there's the dual esc made specifically for it, but I only need it for one motor and I'm trying to save money.
The esc is a Parkflyers 301450 Parkflyers 30 Amp Brushed Esc. The specs that I found were:
30 amp brushed speed control. Stock ESC for Cessna 182 Pro Deluxe#44; Decathlon#44; Edge 540T Brushed and Begin-Air. Specifications:Input voltage: 5v-14.4v#44;Output currency: 30A/50A (Max)#44;BEC: 5V/1A#44;Auto cut-off voltage: 5V#44;Starting: throttle in min (starting point: 1.0-1.5ms)#44;Dimension: 21*32*10mm#44;Weight: 15g
All that i need to know is if they'll work together. And if not, what sort of esc would I need to get?
Any help would be appreciated, thanks.
The sumo bot that I'm building, i figured, would be pretty similar to an r/c car, but it's going to be moving a lot slower and it only two minutes of runtime. I did a little research with the motors, but not much. I'm looking at the 550 hpi gt motor since it seems to be the strongest motor I could find that fit in the competition restrictions of 14.4 v. The part that really confuses me though is the ESC. I have no idea which one I would need for this motor. Googled some but all of the ones that i saw were really expensive... except for one. I was hoping someone could tell me if it would work with it. I also know that there's the dual esc made specifically for it, but I only need it for one motor and I'm trying to save money.
The esc is a Parkflyers 301450 Parkflyers 30 Amp Brushed Esc. The specs that I found were:
30 amp brushed speed control. Stock ESC for Cessna 182 Pro Deluxe#44; Decathlon#44; Edge 540T Brushed and Begin-Air. Specifications:Input voltage: 5v-14.4v#44;Output currency: 30A/50A (Max)#44;BEC: 5V/1A#44;Auto cut-off voltage: 5V#44;Starting: throttle in min (starting point: 1.0-1.5ms)#44;Dimension: 21*32*10mm#44;Weight: 15g
All that i need to know is if they'll work together. And if not, what sort of esc would I need to get?
Any help would be appreciated, thanks.
02-11-2011, 03:30 AM
#2
Tech Regular
iTrader: (2)
Hi,
If the sumo bot is more like an R/C car you may not need 14V at all. Seeing it's going to be slower you could probably make do with a motor/esc combo out of an RTR (ready to race) that someone is not using or has upgraded. A lot would depend on the size of the bot and how much power you will need. Don't worry about run time, even with cheap batteries you will still do 2 mins pretty easily.
There is a brand new set in the for sale section from a Losi SCT that may suit your needs.
http://www.rctech.net/forum/r-c-item...i-xxx-sct.html
The ESC you mentioned is for a plane and is not really suitable for ground use. 540 is the standard motor size and 550 is bigger so normally requires a higher rated ESC to handle the extra power. As well as motor size there is the brushed and brushlesss thing to consider but if it's for a school project and cash is limited then you don't need the fanciest gear out there. Even for the R/C unit you can get away with cheap Chinese gear which is pretty good value for money.
How big is the sumo bot? What does it have to do? How heavy will it be? Many factors like that will determine what is best suited for you.
Feel free to ask more questions if you need to, there are lots of knowledgable people on this site. Most of all, have fun
If the sumo bot is more like an R/C car you may not need 14V at all. Seeing it's going to be slower you could probably make do with a motor/esc combo out of an RTR (ready to race) that someone is not using or has upgraded. A lot would depend on the size of the bot and how much power you will need. Don't worry about run time, even with cheap batteries you will still do 2 mins pretty easily.
There is a brand new set in the for sale section from a Losi SCT that may suit your needs.
http://www.rctech.net/forum/r-c-item...i-xxx-sct.html
The ESC you mentioned is for a plane and is not really suitable for ground use. 540 is the standard motor size and 550 is bigger so normally requires a higher rated ESC to handle the extra power. As well as motor size there is the brushed and brushlesss thing to consider but if it's for a school project and cash is limited then you don't need the fanciest gear out there. Even for the R/C unit you can get away with cheap Chinese gear which is pretty good value for money.
How big is the sumo bot? What does it have to do? How heavy will it be? Many factors like that will determine what is best suited for you.
Feel free to ask more questions if you need to, there are lots of knowledgable people on this site. Most of all, have fun
02-11-2011, 11:38 AM
#3
The idea with the sumo bot competition is to push out you opponent from a 5ft by 5ft ring, so I figured that the most powerful motor would be best (anything wrong with excessive power?). It can't weigh any more that 2kg and must fit within a 40cm by 40cm by 40 cm cube. Max of 14.4v.
My plan was to build the inside first and then cover it in a shell that I would use to push the other bot out. I'm planning to have 1 motor for each wheel (so an ESC for each motor) so that I can maneuver around the ring easily.
Also, I found that the RPM for a 550 hpi gt motor is about 33700 rpms, so I figured that a 1:72 gear ratio would be needed to make it go slow enough. Is a 1:72 ratio resonable? I honestly don't know.
My plan was to build the inside first and then cover it in a shell that I would use to push the other bot out. I'm planning to have 1 motor for each wheel (so an ESC for each motor) so that I can maneuver around the ring easily.
Also, I found that the RPM for a 550 hpi gt motor is about 33700 rpms, so I figured that a 1:72 gear ratio would be needed to make it go slow enough. Is a 1:72 ratio resonable? I honestly don't know.
02-12-2011, 02:09 AM
#4
Tech Regular
iTrader: (2)
Thanks for more info.
RPM alone is not an indication of how much power a motor will produce. You also need to think about the amount of torque that the motor will give. Torque will be much more valuable than RPM for what you are trying to achieve. 33,000 RPM seems high but in reality it is not. A brushless 3.5T will produce 70-80,000 RPM but will be total overkill for your project. A 55T Crawler motor will be slow and have low RPMs but will have more torque where you need it. A 1:72 ratio will not be suitable for the bot, You will want a big spur and smaller pinion. A lot of it is about getting power to the wheels, not how much power you have.
Trying to put a motor on each rear wheel will lead to lots of problems and make the bot quite difficult to control and set up with 2 esc's because one motor will be working in reverse. With only a 5ft by 5ft ring you really need to think what will work best in a tight space. A tank like drive train would be the most suited but would weigh too much. Something that is smaller and more maneuverable will be more suited than something larger (unless it HAS to be). Being able to turn the rear wheels like a forklift will also work and give you a very very small turning circle.
How much scratch building do you need to put into the bot? There are many parts you could scavenge off an old R/C car that would be quite useful (and save time/building costs). The type of surface you will compete on will determine the best kind of tyres to use. Having the weight down low will also help the CG immensely. Think about the truck at the airport that pushes the planes off the terminal gates. It's very low with big tyres and doesn't weigh anything near as much as a fully loaded 747 but pushes it with easily.
Using R/C batteries you wont really need 14.4V. The extra weight of the 2nd battery could be used elsewhere. For the body a very simple wedge shaped one will be the easiest and if the bot is low enough then other bots will simply go over the top rather than push you out of the way. A door wedge works in exactly that way. Remember that you want the weight LOW so a sheet of aluminium would be enough
Here are a few pages for you to look at. Please read them as they have some useful information that can help you. Planning and design is very important but can be fun too.
http://www.howstuffworks.com/gears.htm
http://www.howstuffworks.com/auto-pa...sus-torque.htm (it's for towing but the principles are similar)
http://users.telenet.be/elvo/ (general R/C stuff)
http://www.lynxmotion.com/c-5-sumo-robots.aspx (sumo robot site)
http://en.wikipedia.org/wiki/Robot-sumo (has some other good links)
RPM alone is not an indication of how much power a motor will produce. You also need to think about the amount of torque that the motor will give. Torque will be much more valuable than RPM for what you are trying to achieve. 33,000 RPM seems high but in reality it is not. A brushless 3.5T will produce 70-80,000 RPM but will be total overkill for your project. A 55T Crawler motor will be slow and have low RPMs but will have more torque where you need it. A 1:72 ratio will not be suitable for the bot, You will want a big spur and smaller pinion. A lot of it is about getting power to the wheels, not how much power you have.
Trying to put a motor on each rear wheel will lead to lots of problems and make the bot quite difficult to control and set up with 2 esc's because one motor will be working in reverse. With only a 5ft by 5ft ring you really need to think what will work best in a tight space. A tank like drive train would be the most suited but would weigh too much. Something that is smaller and more maneuverable will be more suited than something larger (unless it HAS to be). Being able to turn the rear wheels like a forklift will also work and give you a very very small turning circle.
How much scratch building do you need to put into the bot? There are many parts you could scavenge off an old R/C car that would be quite useful (and save time/building costs). The type of surface you will compete on will determine the best kind of tyres to use. Having the weight down low will also help the CG immensely. Think about the truck at the airport that pushes the planes off the terminal gates. It's very low with big tyres and doesn't weigh anything near as much as a fully loaded 747 but pushes it with easily.
Using R/C batteries you wont really need 14.4V. The extra weight of the 2nd battery could be used elsewhere. For the body a very simple wedge shaped one will be the easiest and if the bot is low enough then other bots will simply go over the top rather than push you out of the way. A door wedge works in exactly that way. Remember that you want the weight LOW so a sheet of aluminium would be enough
Here are a few pages for you to look at. Please read them as they have some useful information that can help you. Planning and design is very important but can be fun too.
http://www.howstuffworks.com/gears.htm
http://www.howstuffworks.com/auto-pa...sus-torque.htm (it's for towing but the principles are similar)
http://users.telenet.be/elvo/ (general R/C stuff)
http://www.lynxmotion.com/c-5-sumo-robots.aspx (sumo robot site)
http://en.wikipedia.org/wiki/Robot-sumo (has some other good links)
02-12-2011, 05:58 PM
#5
why would having 2 motors make it harder to maneuver? i was planning to have only two wheels, that way I could have a differential drive which I figured would make it easier to control. I don't understand what sort of problems it would make.
02-13-2011, 07:59 AM
#6
Tech Regular
iTrader: (2)
From a regular r/c car point of view it would be a nightmare because of the way the equipment is designed, Its not impossible though. The easiest way using regular r/c ESCs is to use two of them and a stick controller. Basically one channel will be for one ESC and the one channel for the other. The biggest issue you would have is that r/c car ESCs go forward/brake/reverse rather than forward/reverse (it's to protect the ESC). With a Dual Serial Motor Controller that would be less of an issue.
For a two motor setup you should be looking more at the design of r/c tanks because thats basically how they work without the tracks. Before spending money on the real parts I suggest you have a look at the link that follows. It's too small for what you need but it is pretty much spot on with your twin motor idea.
http://www.pololu.com/catalog/product/61
For a two motor setup you should be looking more at the design of r/c tanks because thats basically how they work without the tracks. Before spending money on the real parts I suggest you have a look at the link that follows. It's too small for what you need but it is pretty much spot on with your twin motor idea.
http://www.pololu.com/catalog/product/61
02-14-2011, 07:59 PM
#7
The twin motor gearbox was great but yes, it was too small. I wasn't really able to find any larger ones, but I think that one of the teachers at my school will be able to help me make one.
So I have a new shopping list for the electronic parts of my project. I just wanted to ask you if these would work:
This motor-
cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270464590222
This ESC-
cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260663295709&hlp=false &rvr_id=210424829952&crlp=1_263602_304652&UA=WVI%3 F&GUID=dbd4f3291260a0aad441c441feb19608&itemid=260 663295709&ff4=263602_304652
And this remote- robotmarketplace.com/products/0-GWS24TR.html
I think they'll work, but i'm not sure.
Thanks Renjie for all your help, I've learned a lot.
p.s. sorry, i'd post the sites as hypertexts, but I'm a new user.
So I have a new shopping list for the electronic parts of my project. I just wanted to ask you if these would work:
This motor-
cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270464590222
This ESC-
cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260663295709&hlp=false &rvr_id=210424829952&crlp=1_263602_304652&UA=WVI%3 F&GUID=dbd4f3291260a0aad441c441feb19608&itemid=260 663295709&ff4=263602_304652
And this remote- robotmarketplace.com/products/0-GWS24TR.html
I think they'll work, but i'm not sure.
Thanks Renjie for all your help, I've learned a lot.
p.s. sorry, i'd post the sites as hypertexts, but I'm a new user.
Last edited by littlekid; 02-14-2011 at 08:02 PM. Reason: p.s.
02-15-2011, 07:26 AM
#8
Tech Regular
iTrader: (2)
It's my pleasure to help. This forum is the best for finding info on many types of r/c vehicles.
All those things will work but keep in mind that they are all at the bottom end in regards to pricing/quality. With the transmitter you will need a receiver as well ($10 on the drop down menu).
The larger gearboxes are used in R/C tanks. Finding one with burnt electronics and stealing the running gear would be much easier than custom building something.
Good luck with your project.
All those things will work but keep in mind that they are all at the bottom end in regards to pricing/quality. With the transmitter you will need a receiver as well ($10 on the drop down menu).
The larger gearboxes are used in R/C tanks. Finding one with burnt electronics and stealing the running gear would be much easier than custom building something.
Good luck with your project.
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