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Offline jman571Topic starter

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Building a remote control robot- need some guidance
« on: February 06, 2008, 08:26:43 PM »
Hello everyone. First off I'd like to thank Mr. Palmisano for the excellent site, and the very informative tutorials located here. So, I've begun planning a remote-controlled robot that I will eventually need built for my computer engineering class. I think I have at least 4 months to do it, and Iím starting wayyy early, so in case I fail miserably I can always just buy a RC car and mod it or somethingÖTo be more specific, the robot will have to compete in a race around a track, the track has 2 levels, with at the most a 100 incline to get up a ramp to the 2nd level. Then, the robots will face off in a race to the opposite sides of the track, and you can meet in a center platform with no walls, and push your opponent off the track  ;D The track is really low friction, made out of sheet aluminum, and there's a couple bridges of plexiglass.

I started off with some lofty idea of building a 4-wheel differential drive bot, with a weapon of some sort, but I think the repeated mantra of KISS on this website finally kicked into my brain, and now Iíve decided to just design & build a 2-wheel differential drive bot, that uses DC motors, with a castor, and no weapon. I want it to be powerful! Also it should have speed control (able to increase/decrease motor speed gradually). I was also considering to make the internals (i.e. reciever, motors) entirely enclosed within a shell, so as to protect the robot.

Iíve read the relevant tutorials a couple times, especially these:
http://www.societyofrobots.com/robot_tutorial.shtml
http://www.societyofrobots.com/remote_control_robot.shtml
http://www.societyofrobots.com/actuators_dcmotors.shtml
http://www.societyofrobots.com/materials_aluminum.shtml
http://www.societyofrobots.com/materials_hdpe.shtml
http://www.societyofrobots.com/mechanics_dynamics.shtml
http://www.societyofrobots.com/mechanics_chassisconstruction.shtml
http://www.societyofrobots.com/mechanics_gears.shtml

And I read these, and a couple of other threads, mostly concerning the construction of a basic R/C car:
http://www.societyofrobots.com/robotforum/index.php?topic=2944.0 (Soldering Guide)
http://www.societyofrobots.com/robotforum/index.php?topic=3139.0 (Basic R/C car help)

So Iíve done most of the research, but now I feel a little lost. Iíve done a preliminary 3D design in Google SketchUp, which is to scale, but I still want to do a few more iterations of my design before I begin to layout the parts separately in SketchUp in a 2D environment. I've attached a few JPGs of it, and here's the link to the uploaded model: http://sketchup.google.com/3dwarehouse/details?mid=a96a26a82a8aa3c29e57317b9baa0505
I was then going to do the following in order:

1.   Purchase enough HDPE (1/4Ē for the main body, and perhaps some other thicknesses)
2.   Purchase a 3-channel receiver and transmitter
3.   Based on the weight of the above parts, better estimate the weight of the robot, and using this: http://www.societyofrobots.com/RMF_calculator.shtml Figure out what motor I will need to purchase.
4.   Buy a High Power Motor Driver/ Speed controller.
5.   Figure out what my power requirements are and buy some batteries.
6.   Assemble

I have a couple of questions. One, I was wondering what tools I need to connect the wiring, I checked out this guide: http://www.societyofrobots.com/electronics_wire_connector.shtml but is this method all-encompassing or will soldering be required?

As you can see I really wanted to make this as simple as possible, and build it without a microcontroller, is there any essential task that this will provide that my remote-control robot will need, or can I do without one, if I get a speed controller?

Finally when using HDPE, what is the best method to connect the pieces? I read the VELCRO, TAPE, AND ADHESIVES tutorial, and it recommends E-6000, which I've never heard of before in my life  ???  I went to the plastics store today, and the guy said that adhesives don't really work that well too, so what is the way to go here?

I just wanted to make sure I am doing this right, and wonít be halfway through building it in a few weeks, realizing I had no real idea what I was doing all along. Any help is appreciated. Just keep in mind, that you can reference parts online, but I don't think I'll be doing online ordering, just buying parts in stores that I find.

Finally, for anyone in the Toronto, Canada area I found a GREAT plastic supply store called Plastic World, here's their site: http://www.plasticworld.ca Looks like they have quite a selection...

Offline cooldog

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Re: Building a remote control robot- need some guidance
« Reply #1 on: February 06, 2008, 08:40:15 PM »
okay

put spacers at the back to help hold the roof

make it only as big as needed- you can stack circut boards and batterys ontop of each other to save space. this helps with weight. make it more arodinamik.

get some high friction aircraft tires

for HDPE you can use cutting boards

for connecting HDPE you can use screws

make it look cool! ;D

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Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #2 on: February 06, 2008, 08:54:32 PM »
okay

put spacers at the back to help hold the roof

make it only as big as needed- you can stack circut boards and batterys ontop of each other to save space. this helps with weight. make it more arodinamik.

get some high friction aircraft tires

for HDPE you can use cutting boards

for connecting HDPE you can use screws

make it look cool! ;D



Oh, lol. I just realized that people will assume I'm leaving the backs and sides open. I just left it like that, so people can clearly see the internals. I think I'm going to enclose the entire thing, then put a hinge on the top, so I can open the "roof" of the bot, to change batteries, turn it on, etc.

Sorry, but could you explain what you meant by using "cutting boards" for the HDPE?

I noticed that the plastics store has cornicopia of selection (http://www.plasticworld.ca/index.asp?pid=3). Given the option, should I go with Lexan or Plexiglas instead?

Also, I read the tutorial that mentions the use of a capacitor and was wondering if I should include this in my circuit to improve the efficency and longevity of the motor.
« Last Edit: February 06, 2008, 10:13:26 PM by jman571 »

Offline cooldog

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Re: Building a remote control robot- need some guidance
« Reply #3 on: February 07, 2008, 06:22:28 AM »
plastic cutting boards you can get from the dollar store are made from HDPE
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Re: Building a remote control robot- need some guidance
« Reply #4 on: February 17, 2008, 02:26:13 PM »
Quote
you can see I really wanted to make this as simple as possible, and build it without a microcontroller, is there any essential task that this will provide that my remote-control robot will need, or can I do without one, if I get a speed controller?
You can do all this without a microcontroller. In fact, it would be really hard to accomplish any of those tasks with a microcontroller! If you use DC motors, you will need an ESC (electronic speed controller). If you use servos, you won't.

Quote
the guy said that adhesives don't really work that well too, so what is the way to go here?
It has a lot to do with the materials you plan to bond, and forces involved. Double sided sticky tape and velcro bond very well to HDPE . . . but you should use screws to be more professional/reliable ;D

Make sure you include screws in your CAD . . . trust me on this.

Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #5 on: February 20, 2008, 02:01:41 PM »
Thanks for all the help. However I'm now back with even more questions  :o

I am now using the RMF Calculator to try and determine what kind of motor I should purchase. I'm pretty unhappy with any of the physical stores that sell these kind of things in my area, as in the only store in my area...I'm a little surprised, I live in a big city (Toronto, Canada) and have only found a few R/C Hobby stores (the ones which cater more towards the gasoline-powered racing cars) that even sell some of the stuff I'm looking for. However I'm currently browsing for motors on http://www.servocity.com and am happy with their selection, and may order everything from them.

Here's my problem. I've picked out this motor:
http://www.servocity.com/html/69_rpm_gear_motor.html

It has the best torque to RPM ratio that I can see (as the RPM increases...the torque decreases  :'() However this gives me an RMF of 0.232 lb*ft*rps.

However I want at the very least 0.25 ft/s of speed. I think this is really slow even for my purposes, but I'm willing to compromise. I tracked down the weights of my various parts (i.e. 8 AA batteries (12V), 0.941 g/cm3 HDPE, motors, reciever) and decided that the worst case scenario my bot would weight 3 pounds. I also have to make it up a 100 incline.

Check this link for my calculated minimum RMF:
[img=http://img444.imageshack.us/img444/9554/motorspecsks6.th.jpg]

Btw, we normally use Metric here in Canada, but because of the prevalence of the imperial units on these R/C supply websites I'm going to use imperial, so bear with me if I made any conversion errors.

I'm just struggling to find some motor that can match this RMF, am I being too ambitious with my speed? Or is my robot just too heavy?

Any more help would be appreciated.
« Last Edit: February 20, 2008, 02:04:08 PM by jman571 »

Offline paulstreats

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Re: Building a remote control robot- need some guidance
« Reply #6 on: February 20, 2008, 06:12:37 PM »
Hi,

 For bonding the hdpe, i would use some kind of acetone / celluslose based paint thinners applied to both surfaces and then pushed together. This melts the plastics on contact, when they are pressed together, the thinners evaporate causeing the two surfaces to bond as if one piece of plastic. It takes about five minutes to set to a point where you can leave it, but after 24hours it usually sets to about 75% strength of the material that you use. Definately try to reninforce parts with holding screws if you can.

 As with choosing the motors, if you use the calculator to determine how much force you need to move your robot, this will be sufficient but unfortunately it wont take into account the fact that you would need to push another robot out of the way, you would want resulting torque to be at least 250% of the value that you get in order to counteract the forces produced by puching the other robot/ car out of the way.

 When it comes to speed, this can be achieved using effective gearing which is where you really need to look for your speed/ torque requirements.

Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #7 on: February 20, 2008, 07:35:22 PM »
As with choosing the motors, if you use the calculator to determine how much force you need to move your robot, this will be sufficient but unfortunately it wont take into account the fact that you would need to push another robot out of the way, you would want resulting torque to be at least 250% of the value that you get in order to counteract the forces produced by puching the other robot/ car out of the way.

 When it comes to speed, this can be achieved using effective gearing which is where you really need to look for your speed/ torque requirements.

The thing you said about needing 250% more torque is completely true! I didn't even think about that, well that's why I came here...Thanks. :D

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Re: Building a remote control robot- need some guidance
« Reply #8 on: February 23, 2008, 01:57:00 PM »
Have you considered doing 4 wheel drive (four motors)?

What RMF do you desire?

Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #9 on: February 24, 2008, 05:58:21 PM »
Have you considered doing 4 wheel drive (four motors)?

What RMF do you desire?

Hi Admin, Thanks for the reply.

When I started thinking about this project, yeah I did consider having a 4 wheel drive bot. I was being ambitious. But after reading the tutorials I decided it would be realistic for someone like me who's never really done this before to instead attempt to build a 2-wheel drive with a castor.

It's also got a lot to do with my budget. As it is, I think I'm going to be just over it. The maximum I'm willing to spend on this venture is $200, and if the final tally goes a little over that, then that's alright, but in the end, this is just a school project, and many other groups (I'm working on it alone) are probably purchasing robot kits, or moding an existing R/C car for less money.

I would consider bringing another person on board to split the costs, but this is still up in the air for me. I haven't ordered any parts yet and when all is said and done, my robot may be a complete failure, and I'll have to rush and buy some kit of some kind...So money isnít a real issue, but given the probability of failure, I'm not willing to spend much more than $200 just to have it all go to waste.

Now...as for my Motor RMF, so I've been throwing around some variables, and I'm willing to compromise on the speed, which would be around 0.25 ft/s but what I haven't determined is my final weight, the numbers I have are all estimates. It's the weight of the batteries, that are really messing up my numbers at this point, I initially just added the weights of 8 AA batteries (12V) to low-ball a total robot weight of 2.73 lb, with a motor RMF of 0.420 lb*ft*rps minimum. But after shopping around for some battery packs, especially some high-capacity NiMH, I think a more realistic total weight is 3.88 lbs, which I rounded to 4 lb for a max estimate. Given this weight, I got a motor RMF of 0.616 lb*ft*rps. So I'm shooting for something around that. The thing is, not a lot of motors are even getting close, and so I think I may be doing some bad estimating. Like when I see a motor all I look at is its specs. I don't have the requisite knowledge to tell whether it's a "powerful" motor or not. I consulted a friend who does build little robots and projects in his spare time (i.e Wii-mote controlled R/C car) and when I was looking at motors, he was saying "these are all more than enough for a tiny robot".... :-[

So I don't know whether I should be consulting the RMF Calculator like its some all-powerful motor deity :o, or go with my gut, and just buy some motors that are close to my RMF, and look "powerful" in comparison to others.

Finally, one more quick question  ;D, I will need 2 speed controllers, correct? Because I was looking at the wiring, and I think you need one for each motor. Not 100% sure though.

Thanks for any additional help! :)

P.S When I go to school on Mon. I think I'll take some pictures of the track just to give you guys some idea of where the robot is going to compete.
« Last Edit: February 24, 2008, 06:02:10 PM by jman571 »

Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #10 on: February 26, 2008, 02:40:59 PM »
I think I may have solved my motor troubles:
http://www.robotshop.ca/home/products/robot-parts/motors/gear-motors/spur-gearmotors/lynxmotion-ghm-14-gear-head-motor.html

I found this beast, that gives me an RMF of 4.43 = wayyy more than I need. But is this overkill?

Actually, for the same cost, this is a bit more feasible: http://www.robotshop.ca/home/products/robot-parts/motors/gear-motors/spur-gearmotors/lynxmotion-ghm-02-gear-head-motor.html

By getting this latter motor I can actually increase my speed to 0.5 ft/s! So I'll wait back to here your suggestions Admin, but I'll add this to my growing list of part websites.

Also I was wondering what is up with this transmitter: http://www.servocity.com/html/ranger_2n.html It's cheap, but it looks like the control stick on the right side only goes left and right...not up or down, not exactly easy to use for a differential drive bot...

One more thing: http://www.robotshop.ca/home/products/robot-parts/motor-controllers/brushed-motor-controllers/all-brushed-motor-controllers/index.html I'm a little intimidated by things that look like circuit boards because I automatically assume complicated things are associated with them, but do these motor controllers standalone or do they hook up with a microcontroller?

Because I'm looking at this one: http://www.robotshop.ca/home/products/robot-parts/motor-controllers/brushed-motor-controllers/all-brushed-motor-controllers/solutions-cubed-motor-mind-c.html

And it looks pretty good, I don't mind soldering either.

This also looks pretty good to me: http://www.robotmarketplace.com/products/0-SABER2X5-RC.html

Attached to this post are a couple pictures of the track, in the second one you can see the narrowest part of it. Notice the large octagonal platform open on all sides! Sorry for the terrible quality, I took them using my cell phone. I promise if I need help later on building this thing, you'll get the clearest 10MP shots you've ever seen...
 

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Re: Building a remote control robot- need some guidance
« Reply #11 on: March 09, 2008, 02:19:25 PM »
Quote
So I don't know whether I should be consulting the RMF Calculator like its some all-powerful motor deity , or go with my gut, and just buy some motors that are close to my RMF, and look "powerful" in comparison to others.

You don't want to go with gut feeling when the math is already done for you :P

When you do the math, you *know for certain* it will do exactly what you want. As for your friend, his small robots obviously don't have the requirements of a heavy robot or high torque that you do. ;)

If weight is an issue, find other ways to reduce it - swap materials (plastic instead of metal), change shape, shrink the body (less material). Or if batteries are too heavy, use smaller ones and just accept that the robot won't run as long. Ask yourself what the heaviest two or three parts are, reduce the weight of each by 10%, and chances are your robot will be 40% lighter.

Quote
I will need 2 speed controllers, correct? Because I was looking at the wiring, and I think you need one for each motor. Not 100% sure though.

correct

Quote
I found this beast, that gives me an RMF of 4.43 = wayyy more than I need. But is this overkill?

Nice find! So your RMF is .6 but that motor gives 4.4? (I'm assuming you did the calculations both in english units?)

Quote
I'll add this to my growing list of part websites.

Those were already in my list :P
http://www.societyofrobots.com/robot_parts_list_motors_servos.shtml

Quote
Also I was wondering what is up with this transmitter: http://www.servocity.com/html/ranger_2n.html It's cheap, but it looks like the control stick on the right side only goes left and right...not up or down, not exactly easy to use for a differential drive bot...

One is meant for throttle and the other for direction. It'll work, but will be annoying to use.

Quote
One more thing: http://www.robotshop.ca/home/products/robot-parts/motor-controllers/brushed-motor-controllers/all-brushed-motor-controllers/index.html I'm a little intimidated by things that look like circuit boards because I automatically assume complicated things are associated with them, but do these motor controllers standalone or do they hook up with a microcontroller?

Make sure in the datasheet that it says specifically that it can accept an RC signal. Some of those drivers can be used with microcontrollers as well as RC. The dimension engineering ones can do all of the above, and some can do two motors.
Oh and just buy them from the manufacturer - much cheaper. Robotshop.ca does resale and marks prices up.

Quote
Because I'm looking at this one: http://www.robotshop.ca/home/products/robot-parts/motor-controllers/brushed-motor-controllers/all-brushed-motor-controllers/solutions-cubed-motor-mind-c.html

And it looks pretty good, I don't mind soldering either.

It can do RC, but you will need one for each motor. Also, are you sure 2.25A is enough for your motors?

Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #12 on: March 11, 2008, 11:18:23 AM »
Wow, thanks Admin that post was great! I'm on vacation right now 8) so I'll get back to whole robot project when I return, but now I at least know what to look for. I did find an additional store that may sell parts in Toronto, so I'll check it out when I get back.  ;D


Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #13 on: March 26, 2008, 07:58:53 AM »
Quote
Quote
Because I'm looking at this one: http://www.robotshop.ca/home/products/robot-parts/motor-controllers/brushed-motor-controllers/all-brushed-motor-controllers/solutions-cubed-motor-mind-c.html

And it looks pretty good, I don't mind soldering either.

It can do RC, but you will need one for each motor. Also, are you sure 2.25A is enough for your motors?


Ya it looks like even 1.5A is enough, I wanted to get the monster motor I linked to, but it's simply too big for my robot dimensions!

Even if layed them end to end, they would be too long. So instead I'm going with this one: http://www.robotshop.ca/home/products/robot-parts/motors/gear-motors/spur-gearmotors/lynxmotion-ghm-02-gear-head-motor.html

Which is also a very good motor, looking at the specs. sheet it says (http://www.robotshop.ca/PDF/rblyn06_spec.pdf) it's max. current draw is 1.5 A at 12V stall current.

I'm most likely going to go with this dimension engineering motor controller: http://www.dimensionengineering.com/Sabertooth2X5.htm

Thanks for the recommendation to go through the manufacturer, their shipping is really cheap. This motor controller actually supports 2 motors, and even has a power supply for the receiver. It's going to bring this robot together (literally :D) and seems worth the price for me (compared to most other motor controllers I've found the price is low).

Thanks for all the help, I should be ordering parts soon.

Actually, while I was going to go and order batteries from http://www.all-battery.com/ if anyone can recommend a better place to buy, it would be appreciated, I was going to just purchase a single 12V battery pack to simplify things, but I'm not averse to putting a couple 6V packs in series, etc.
« Last Edit: March 26, 2008, 08:02:28 AM by jman571 »

Offline cooldog

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Re: Building a remote control robot- need some guidance
« Reply #14 on: March 26, 2008, 02:05:42 PM »
Actually, while I was going to go and order batteries from http://www.all-battery.com/ if anyone can recommend a better place to buy, it would be appreciated, I was going to just purchase a single 12V battery pack to simplify things, but I'm not averse to putting a couple 6V packs in series, etc.


try www.onlybatterypacks.com
« Last Edit: March 26, 2008, 07:14:41 PM by cooldog »
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Offline airman00

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Re: Building a remote control robot- need some guidance
« Reply #15 on: March 26, 2008, 04:51:52 PM »
Actually, while I was going to go and order batteries from http://www.all-battery.com/ if anyone can recommend a better place to buy, it would be appreciated, I was going to just purchase a single 12V battery pack to simplify things, but I'm not averse to putting a couple 6V packs in series, etc.


try www.onlybatterypack.com



its try www.onlybatterypacks.com
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

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Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #16 on: March 27, 2008, 09:36:13 PM »
Thanks for that site recommendation, I may just go with them.

So, I'm about ready to order my parts, but I have a final round of questions. But first, here's my growing major parts list:

Part
Transmitter
Reciever
Motor
Battery
Battery Charger
motor controller
Name
75Mhz 4-channel Radio System
75Mhz 4-Channel Pico Receiver - Horizontal Pins - Futaba-Style
Lynxmotion 12VDC 120RPM 123.2oz-in GHM-02 Spur Gear Head Motor
12v 2600mah NiMH 10 cell AA Pack
12v DC 300mAh Battery charger
Sabertooth 2X5 dual 5A motor driver for R/C
Link
http://www.robotmarketplace.com/products/0-GWS-GWT4A.html
http://www.robotmarketplace.com/products/0-GWR4PII75HF.html
http://www.robotshop.ca/home/products/robot-parts/motors/gear-motors/spur-gearmotors/lynxmotion-ghm-02-gear-head-motor.html
http://www.onlybatterypacks.com/showitem.asp?ItemID=11128.37
http://www.onlybatterypacks.com/showitem.asp?ItemID=10084.12
                                                   
http://www.robotmarketplace.com/products/0-SABER2X5-RC.html

Now...the questions.

I'm still considering what kind of wheel to go with. I was considering going with these: http://www.robotshop.ca/home/products/robot-parts/mechanics/robot-wheel-track/off-road-robot-tire.html But it seems mounting hubs are also required, meaning they'll cost me almost $40 in total.

This wheel is another pricey, albeit cheaper, alternative: http://www.robotshop.ca/home/products/robot-parts/mechanics/robot-wheel-track/lynxmotion-sumo-tire-lyn-16.html

Keep in mind the surface of the race track is sheet aluminum, and the robot must make it up a 10o
incline. I was considering going with foam wheels, they seem to be the cheapest, but I have qualms about their ability to grip the track and provide enough traction. As well, the motor shaft diameter is 6mm, so the wheel/hub would have to be that size or smaller (I could always drill a larger hole). Any decent wheel recommendations?, I am looking for something in the 3-5" diameter range.

My next question concerns my battery source. For a reliable connection I was either going to go with a Deans Ultra connector(http://www.onlybatterypacks.com/showitem.asp?ItemID=10069.14) or a BEC connector (http://www.onlybatterypacks.com/showitem.asp?ItemID=11417.14). When ordering from www.onlybatterypack.com they do give you the option of using any connector, but does this still mean I would need to do some soldering to affix the connector to a bare lead, or is everything already attached? Or perhaps I should go with Admin's tutorial and use the connection method used there (http://www.societyofrobots.com/electronics_wire_connector.shtml) which requires a crimper and pins?

Many thanks for any recommendations of where I should proceed from here. I really do need to order all the parts soon, I was hoping as soon as tomorrow if possible, because I think shipping could take quite some time.
« Last Edit: March 27, 2008, 09:51:41 PM by jman571 »

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Re: Building a remote control robot- need some guidance
« Reply #17 on: March 28, 2008, 05:27:18 AM »
for wheels  would go with the sumo tires they have great traction

also the BEC connector is a god niversal connector

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Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #18 on: March 28, 2008, 08:09:40 AM »
for wheels  would go with the sumo tires they have great traction

also the BEC connector is a god niversal connector



Ok...but they do not have a tread, which concerns me.

Alright...I ordered everything...yay!
« Last Edit: March 28, 2008, 09:34:53 PM by jman571 »

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Re: Building a remote control robot- need some guidance
« Reply #19 on: March 30, 2008, 10:04:43 AM »
Quote
But it seems mounting hubs are also required, meaning they'll cost me almost $40 in total.

Pretty easy/cheap to just make your own.

Quote
Keep in mind the surface of the race track is sheet aluminum, and the robot must make it up a 10o
incline. I was considering going with foam wheels, they seem to be the cheapest, but I have qualms about their ability to grip the track and provide enough traction. As well, the motor shaft diameter is 6mm, so the wheel/hub would have to be that size or smaller (I could always drill a larger hole). Any decent wheel recommendations?, I am looking for something in the 3-5" diameter range.

Foam wheels can grip a 10 deg surface no problem. If you are really worried about traction, you can add rubber to your wheels:
http://www.societyofrobots.com/robot_ERP.shtml#changes

Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #20 on: March 30, 2008, 01:06:30 PM »
Quote
But it seems mounting hubs are also required, meaning they'll cost me almost $40 in total.

Pretty easy/cheap to just make your own.

Quote
Keep in mind the surface of the race track is sheet aluminum, and the robot must make it up a 10o
incline. I was considering going with foam wheels, they seem to be the cheapest, but I have qualms about their ability to grip the track and provide enough traction. As well, the motor shaft diameter is 6mm, so the wheel/hub would have to be that size or smaller (I could always drill a larger hole). Any decent wheel recommendations?, I am looking for something in the 3-5" diameter range.

Foam wheels can grip a 10 deg surface no problem. If you are really worried about traction, you can add rubber to your wheels:
http://www.societyofrobots.com/robot_ERP.shtml#changes


Ahh thanks Admin, that's a very neat idea. So everything is good so far except for my motors  >:( It seems RobotShop had only one left in stock, and the manufacturer (Lynxmotion) is also out of stock, so it will be "several weeks" until more are available. Realistically, I could wait that long, I made sure I'd have more than enough time in shipping delays, but I'd like some motors sooner, because they're important to finalizing my design. So now to find something else, maybe I WILL go with that motor with an RMF of 4.43...

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Re: Building a remote control robot- need some guidance
« Reply #21 on: April 21, 2008, 08:37:46 PM »
OK so I felt it was time for another update. I've received all my robot parts and I feel like I'm ready to make some substantial progress. I may decide to open up a Flickr account, to showcase some of my build photos, because I won't be able to host anything here.

EDIT: Just to make this easier, and to have the pictures dispersed among the text, I set up the flickr account. http://www.flickr.com/photos/12017635@N07/

I however have some more stupid n00b questions for you guys... :-[

Ok first off, I realized I needed a couple more things than I had originally planned out for. The first being, wires that actually connect to my motor leads  :o So I was just going to go and solder some on...sound good, I thought so....I have some random wire that I found in my basement, and on a positive note, I also found a mini switch...which I'm so psyched to use, so I'll include that in my circuit...somewhere.


Next off, I also have a battery for my transmitter, that is 9.6V and thus, seems to be compatible with the battery charger that I bought. However I don't think the connectors match up..or do they? Because I'm looking at the charger, and there seems to be 4 wires running from it, 2 for the tamiya/kyosha connector (which connects to a deans ultra via another piece of wire...don't ask why I decided to have all these different connectors...) and another 2 wires leading to a Red BEC, which leads to this strange piece:


I was just wondering what this is?



OK, so in the next picture the green battery on the left is the 9.6V transmitter battery, and it uses a Red BEC connector, and the strange piece connected to a BEC as well, so by removing the strange piece, can I now connect my transmitter battery? Will it even charge using this wire? Or will I need to get ANOTHER adapter wire for the tamiya/kyosha connector (which seems to be the primary way to charge a battery).

Sorry if this entire post was confusing as hell, that's why I hoped the pictures would help. Check out my Flickr page and I may post some new stuff tomorrow. Thanks for any info.

Offline AndrewM

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Re: Building a remote control robot- need some guidance
« Reply #22 on: April 21, 2008, 09:27:54 PM »
I took a peak on the Tenergy website and couldn't find anything on that extra little plug off the BEC that you show in the photo.  I have seen those on other Tenergy battery chargers in photos on retail websites though.  Seeing as the wire going to the connector is all black, and not a red and black pair, I would be inclined to believe it is not a battery charging circuit, but rather something else.  Perhaps it is a thermal sensor designed to sit on the battery during charging?

Either way, you would be better off making (or purchasing) an adapter to go from BEC to Tamiya.  I've had to do that in the past for my lipo batteries because the charger is always BEC, and I prefer to use Tamiya connectors on the batteries (no possible chance of plugging one in backward and unlikely to accidentally short the ends).
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Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #23 on: April 21, 2008, 09:59:59 PM »
I'm sure Admin will know what it is...he got the exact same charger as me  ;D

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Re: Building a remote control robot- need some guidance
« Reply #24 on: April 26, 2008, 05:19:47 PM »
Quote
I'm sure Admin will know what it is...he got the exact same charger as me
actually, I dont - they look similar though . . .

as for that thingy . . . hmmmm its not in the instructions that came with the charger?

what happens if you plug it in and turn it on? it looks like an LED of some sort . . .

my guess is maybe its for discharging a battery - plug it in to a battery, and it slowly drains it . . . but really I don't know . . .

Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #25 on: April 27, 2008, 01:35:53 PM »
Quote
I'm sure Admin will know what it is...he got the exact same charger as me
actually, I dont - they look similar though . . .

as for that thingy . . . hmmmm its not in the instructions that came with the charger?

what happens if you plug it in and turn it on? it looks like an LED of some sort . . .

my guess is maybe its for discharging a battery - plug it in to a battery, and it slowly drains it . . . but really I don't know . . .

lol, so it turns out the charger won't charge without that weird thing plugged in, the LED on the charger was flashing red and until I plugged in the piece it wasn't charging  :o

Also Admin, I just went back to onlybatterypacks.com to check this out. And here's the funny thing, in your other thread you complained about the charger you bought, and the the link brings you to the page of the EXACT same charger that I bought. However, it seems they shipped me something different, a Tenergy charger, not the one shown in the picture on onlybatterypacks.com. Not the same charger that you recieved. Either there was a mix-up (I hope I got a 12V charger....otherwise >:() or your complaint made them change that product  :-\
« Last Edit: April 27, 2008, 01:37:01 PM by jman571 »

Offline airman00

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Re: Building a remote control robot- need some guidance
« Reply #26 on: April 27, 2008, 06:45:46 PM »
hey

i have that charger , the Tenergy one

I have both the 4.8V to 7.2V version and the 7.2V to 12V version. I am satisfied with both they both work fine

When the LED is red its charging when its green its done charging
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Re: Building a remote control robot- need some guidance
« Reply #27 on: April 27, 2008, 09:18:29 PM »
hey

i have that charger , the Tenergy one

I have both the 4.8V to 7.2V version and the 7.2V to 12V version. I am satisfied with both they both work fine

When the LED is red its charging when its green its done charging
It was blinking red until I hooked that weird piece back in, I guess that's the LED signal for "there is a serious problemo"  ;D

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Re: Building a remote control robot- need some guidance
« Reply #28 on: April 27, 2008, 09:52:48 PM »
which wierd piece

the fuse?

but yea blinking red is problemo
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Offline jman571Topic starter

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Re: Building a remote control robot- need some guidance
« Reply #29 on: April 27, 2008, 10:05:26 PM »
which wierd piece

the fuse?

but yea blinking red is problemo

lol, guess it was the fuse? I'm not sure...look further up this thread, for when I asked about the "weird piece", there are pictures there....ahh nvm, this is what I'm talking about:

 


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