help with my RC robot

[trickyotool]

firstly i am sorry because you are going to think i am a idiot  but i have hit a road block in my path. my aim is to build a RC robot for speed i decided to go with your kiss thing and choose a differential drive system with a caster. i plan to try and find a low resistance Castor and high resistance big wheels at the back (maybe some sumo wheels from active robots) is this right for my whole speed idea ? I have found an old 6 channel receiver and a remote control transmitter from an RC airplane i crashed on its maiden flight (it was never repaired) which i plan to use. for the motors i was thinking of using the 12V Gear Head 595 RPM
(http://www.active-robots.com/products/motorsandwheels/gearhead-motors.shtml)
the main reason i thought this motor would be good is it is light and it has a high RPM. With those motors can you use this motor mounting bracket i am pretty sure you can but i want to make sure before i spend money on it as with all this stuff.
(http://www.active-robots.com/products/motorsandwheels/easy-roller.shtml)
with the speed controller i got a bit confused but i think this one would work well with the two motors is that right ?
(http://www.active-robots.com/products/motorcon/md32-details.shtml)
 
my main query is with the battery's (i tried to use the calculators but it didn't go well and probably left me a bit more confused)with a little help from my granddad i think the 2 motors need a combined wattage of 49.2 watts i take it it is impossible for you to get this in 1 small battery pack. Now i would like to keep it down to as few battery packs as possible but i think it has to be at least 2. so what about this GP TC206 3900mAh Powerpack
(http://www.active-robots.com/products/power-supplies/sanyo-3600ma-batterypack.shtml)
which gives out 28.08 watts so two of these packs give me 56.16 watts will this work or am i talking rubbish. i also have no idea if i should put these battery packs in series or parelel what do i need more volts or more current again i have no idea ?

also i am currently not sure about what wires to get to wire it all up. it may seem a little dumb but i am pretty sure you cant get any old wire to connect the motor to the speed controller for example. probably my main question is will all these parts work together and will it be fast ?

anyway i think that is it for the time being any help will be much appreciated

Thank you           

[ALZ]

Hi:
Since no one seems to want to help you, I'll throw in my 2 cents. You may want to buy a "VEX" kit on EBAY when you can find a low price.  If you still want to build it from the parts you listed, here are some tips:

You can not use the "MD23" because it has no R/C radio input. Also it will not work at 7.2 volts which is the battery you wanted to use. If you put two batteries in series that would give you 14.2 volts which is a higher voltage than the "MD23" can take.
Their "AX500" has a R/C radio input and takes 12 v to 24 v

The 49.2 watts for the two motors are only if the motors are "locked shaft". That means if the motors can't turn. A good guess would be the 2 motors together would take about 800 ma under a load.

You have to wired the 2 batteries in series to give you enough voltage to run the "AX500"

You are a little off on your thinking when it comes to the batteries. The "56.16 watts" is what is called "watt hours" It means that the batteries can give you 56.16 watts for 1 hour. It can give you more power than 56.16 watts but for a shorter amount of time.

firstly i am sorry because you are going to think i am a idiot  but i have hit a road block in my path. my aim is to build a RC robot for speed i decided to go with your kiss thing and choose a differential drive system with a caster. i plan to try and find a low resistance Castor and high resistance big wheels at the back (maybe some sumo wheels from active robots) is this right for my whole speed idea ? I have found an old 6 channel receiver and a remote control transmitter from an RC airplane i crashed on its maiden flight (it was never repaired) which i plan to use. for the motors i was thinking of using the 12V Gear Head 595 RPM
(http://www.active-robots.com/products/motorsandwheels/gearhead-motors.shtml)
the main reason i thought this motor would be good is it is light and it has a high RPM. With those motors can you use this motor mounting bracket i am pretty sure you can but i want to make sure before i spend money on it as with all this stuff.
(http://www.active-robots.com/products/motorsandwheels/easy-roller.shtml)
with the speed controller i got a bit confused but i think this one would work well with the two motors is that right ?
(http://www.active-robots.com/products/motorcon/md32-details.shtml)
 
my main query is with the battery's (i tried to use the calculators but it didn't go well and probably left me a bit more confused)with a little help from my granddad i think the 2 motors need a combined wattage of 49.2 watts i take it it is impossible for you to get this in 1 small battery pack. Now i would like to keep it down to as few battery packs as possible but i think it has to be at least 2. so what about this GP TC206 3900mAh Powerpack
(http://www.active-robots.com/products/power-supplies/sanyo-3600ma-batterypack.shtml)
which gives out 28.08 watts so two of these packs give me 56.16 watts will this work or am i talking rubbish. i also have no idea if i should put these battery packs in series or parelel what do i need more volts or more current again i have no idea ?

also i am currently not sure about what wires to get to wire it all up. it may seem a little dumb but i am pretty sure you cant get any old wire to connect the motor to the speed controller for example. probably my main question is will all these parts work together and will it be fast ?

anyway i think that is it for the time being any help will be much appreciated

Thank you           

[trickyotool]

thank you for taking the time to reply. firstly the vex kit looks good but i would still like to build my own from separate parts. also i did think about the beo-bot kit but i want to build a remote control robot first.  and then move on to autonomous robot (maybe even customize this one to be autonomous) and to start that off i will probably buy one of them kits. can you even call what i am planning a robot or is it just a remote control vehicle?

Alright i have scrapped the MD23. the AX500 looks good but it cost 3 times more. i don't mind buying that if i have to but i am going to try and look for something a little cheaper. saying that i will probably go for this one anyway. If afterwards i was going to build an autonomous robot can i reuse this part for that?

so with the motors using 800ma two motors will use roughly 19.2 watts but one of their battery's gives out 28.08 watts so i can get away with using 1 battery pack. except for the one battery pack is only 7.2V and the AX500 needs at least 12V is this right? two of the battery's with the 56.16 watts seems to me like a bit of an overkill am i right? so i started to look at other batteries the GP TC201 1600mAh Powerpack 2 of them gives 30.72 watts and a total of 19.2V where as the 6.0vdc 2800mAh Powerpack 2 of them gives out 33.6 watts and 12V. (http://www.active-robots.com/products/power-supplies/sanyo-3600ma-batterypack.shtml)

personally i am going towards the GP TC201 1600mAh Powerpack. it is roughly the same (watts and voltage) but weighs a little less. so i put two of them in series is that ok or would it then bring the voltage above 24V?

i know what you said about watt hours and i am sure i can get smaller battery packs that will work fine for this. yet i think they are a good size for this and other future projects. also this is a bit irrelevant at the moment but do you think a little mini spoiler would help. to push the tires down and give me a bit more speed or is that just pointless (i have been looking at drag cars for inspiration).

i am also making an actual size cad model on google sketch but without the wires and screws i will post that as soon as i have finished it

Thank you for any help

[Darkbluestar]

For the motor controller you can get a cheaper alternative. Your motors use 2A at peak while the AX500 can output 15A. It isn't bad, but if your only going to use the motor controller for small to medium robots then the AX500 is overkill. I would suggest something like the Sabertooth from dimension engineering the 2x5 would work for your application. It can output 5A continuous. I personally own 2 of these and I love them.

http://www.active-robots.com/products/motorcon/sabertooth.shtml

[ALZ]

Hi trickyotool:

By all means shop around. I assume that you picked the web site you did because you don't live in the U.S.

"If afterwards i was going to build an autonomous robot can i reuse this part for that?"
Yes

"so with the motors using 800ma two motors will use roughly 19.2 watts"
No, the 2 motors will use a total of 800ma or 9.6 watts.

"so i can get away with using 1 battery pack. except for the one battery pack is only 7.2V and the AX500 needs at least 12V is this right? two of the battery's with the 56.16 watts seems to me like a bit of an overkill am i right? "
Yes

"I have found an old 6 channel receiver and a remote control transmitter from an RC airplane i crashed on its maiden flight (it was never repaired) which i plan to use. for the motors i was thinking of using the 12V Gear Head 595 RPM"

May I ask what happen to the servos? You know you could use them to make your 1st robot. It may not be fast but it would save you lots of money. 

"also this is a bit irrelevant at the moment but do you think a little mini spoiler would help. to push the tires down and give me a bit more speed or is that just pointless (i have been looking at drag cars for inspiration). "

 You know the motors you want to use have no oz. per in. specs. I can tell you at 400 ma the motor is not going to be a power house.

[trickyotool]

thanks again for the help. you are right i live in the uk and would like to keep the number of websites i order from to a minimum. for the body i was going to use HDPE and i wanted to know if anyone has a good uk website to use or if they have tried this website:
(www.directplasticsonline.co.uk)

now for the motor controller i am not going to go with the AX500 anymore. it looks good but i think that it would be better if i went for a smaller and cheaper one for now (its not like i am planning on building massive robots at the moment). i am planning to get the sabertooth 2X10 although i will not reach the 10A limit, there is only a £10 price difference from the 2X5 and if i brought the 2X5 and my next robot needed 6A it will cost me another £47. what do you guys think about the 2X10? another query i have about the 2X10 is will it power the receiver or do i need a ParkBEC or another power supply? i dont think i do but i want to make sure.

May I ask what happen to the servos? You know you could use them to make your 1st robot. It may not be fast but it would save you lots of money. 

i have got 2 but 1 does not work. i thought you needed a micro controller to get them to rotate the full 360 degrees. at the moment it rotates 90 degrees. i was planning on cutting of there leads to connect the receiver to the motor controller. or at least cut the lead of the one that doesn't work.

i decided to use 1 powerpack now that the motor controller can run with just 6V. i am going to go with GP TC206 3900mAh Powerpack again. i think it will work well. my robot can run for a decent amount of time and its a good choice to use with future robots. to connect it to the motor controller can i use this Heavy Duty Wiring Harness or the Tamiya Wired Connectors:
(http://www.active-robots.com/products/power-supplies/sanyo-3600ma-batterypack.shtml)
Also i need to start looking a battery chargers i do not want a slow charger. yet i don't know which one to get between these two the Pro–Peak AC Delta Base Fast Charger or the Wattage Fast Charger
(http://www.active-robots.com/products/power-supplies/sanyo-3600ma-batterypack.shtml)

with wiring the whole thing up i am pretty sure i know how to do it, but i am not sure what wire to get to connect the motors to the motor controller?

All help is much appreciate

[Webbot]

i was going to use HDPE and i wanted to know if anyone has a good uk website to use or if they have tried this website:
(www.directplasticsonline.co.uk)

I have used directplasticaonline - they were very fast turning aound the order and I would definitely use them again.

[ScorpIon]

http://www.societyofrobots.com/step_by_step_robot_british_parts.shtml

[Darkbluestar]

Straight from the Sabertooth Description "Sabertooth has a built in 5V BEC that can provide power to a microcontroller or R/C receiver. " So you should be able to power your receiver from it.

[Webbot]

http://www.societyofrobots.com/step_by_step_robot_british_parts.shtml

Yea - that's fine for the electronic components but doesn't address the 'poster's question re HDPE, battery charges etc let alone hookup wire, crimping tools and all the other stuff that a 'first time' person needs. In fact the biggest problem I've found in the UK is the Molex connector hoods (like those that come on the ends of your servo). Yes - you can buy pre-built leads at a price of $2.50 each but there must be a cheaper way. I ended up having to go via Digikey with a minimum order of $200 !!! You also have companies like RS Components who do the molex C Grid III connector but they are notoriously expensive or they want you to buy 1000 units at a time.

[ALZ]

Hi:

"i thought you needed a micro controller to get them to rotate the full 360 degrees. at the moment it rotates 90 degrees"

No, the micro controller is not what lets them  rotate the full 360 degrees. If you search on this site you will find out how to open them up and make it run 360.

Also you may want to think about getting a  motor that is gear down more. The "Gear Head 595 RPM" may be too fast without enough power.

[trickyotool]

Sorry it took so long to reply had some internet problems. now with the servo modification i did already know about that because i tried it about 3 months ago and thats how i broke the other servo. i am bit nervous about doing it again. the servo that does not work will constantly move back and forth uncontrollably

I have used directplasticaonline - they were very fast turning aound the order and I would definitely use them again.

thanks for the comment on that website i will order the HDPE from there.

http://www.societyofrobots.com/step_by_step_robot_british_parts.shtml

That link does not really help me but i probably will build the $50 robot after this one. at the moment i am happy with remote control robots.

Straight from the Sabertooth Description "Sabertooth has a built in 5V BEC that can provide power to a microcontroller or R/C receiver. " So you should be able to power your receiver from it.

sorry i missed that in the description maybe because i thought they where called ParkBEC not just BECs but thanks i was worried about that.

at the moment i am just going to order the made up molex connect hoods as i do not really want to order 1000 of them

now about the motor. i take it you do not think it has got enough torque to get up any little incline. i am a bit worried about that. i have had a look at other motors but do i need a motor that has a stall torque value? saying that i have listed 3 different motors any opinions on which one to get (or other motors) would be appreciated:

1) Gear Head Motor (12Vdc, 595RPM)        the original choice
2) Gear Head Motor (12Vdc, 253RPM)        this motor has a stall torque value. with this one does the spoiler question come back into it
3) Gear Head Motor (12Vdc, 416RPM)        and this one just has a smaller RPM
(http://www.active-robots.com/products/motorsandwheels/gearhead-motors.shtml)

[airman00]

what kind of terrain do you want this robot to go on?

if its outdoor then I would do a 4WD

[trickyotool]

it would probably be outdoors but i might still want to use it indoors on occasions. i take it with 4WD you can still use a differential drive system? now with the 4WD idea how would i do that? 4 motors 2 motor controllers or could you just connect the left side motors to the same left side section on the motor controller. if that makes sense.

what about to give it more traction i try to use 2 motors but add a tank track thing like this:
(http://www.active-robots.com/products/platforms/tri-track.shtml)
i am going to look into the 4wd idea and will get back to you

[jman571]

I'm not going to give you too much advice right now, because my own RC robot is no where near successful at this point, but I can recommend reading this: http://www.dimensionengineering.com/appnotes/simple_robot/simple_robot.htm To get a better idea of what you need to do.

I purchased the Sabertooth 2X5 R/C from Dimension Engineering, and so far I'm very impressed by it, but I have to hold out on the GO GET ER' recommendation, because my RC circuit is not working, and it is a remote possibility that the Sabertooth could be the culprit, though if this is true it could just be an unfortunate lemon, otherwise the product looks very good IMO.

[trickyotool]

thanks for the info but at the moment i have put this project on hold for a week or two while i do some fund raising and i am currently finishing off another project. when i get back to this i will start up a new page.

[trickyotool]

one more thing i read your forum post it is a good one and good luck with your rc bot