Author Topic: General questions (newbie)  (Read 1935 times)

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Offline you eat wafflesTopic starter

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General questions (newbie)
« on: February 19, 2010, 11:14:14 PM »
I'm new to robotics and such. I want to make just a simple rover with 4 wheels, but it's no fun if you have a cord attatched to it. I don't have a controller or a transmitter and i'm not very rich, is this a good starter? http://www.robotmarketplace.com/products/0-SPM5500.html . I get alot of the electronics portion but just have never done radio control, what transmitter would I need? is it hard to hook up, is there any programing? Is there a better transmitter for the same price? Can it control servos? Thanks for your help, I really appreciate it  :) Oh I also have been looking around the fourms for a good starter kit, What items should I purchase that I will need time and time again. (I feel very inquisitive today lol) :D
« Last Edit: February 20, 2010, 07:56:09 AM by you eat waffles »

Offline RobotBits

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Re: General questions (newbie)
« Reply #1 on: February 20, 2010, 04:53:35 PM »
It largely depends on what you are trying to achieve with your robot?

Radio control works well if you building an inspection or surveillance robot - all you need to add is a wireless video camera system, so you can pilot your robot remotely, and you're away - no programming necessary.

If you are looking to build an autonomous robot the requirements are quite different - you'll need a choose a programmable controller (such as an Arduino) to carry out tasks such as navigation, line following and obstacle avoidance. In this case some programming will probably be required.

If you can be a little more specific about your objectives, we'll try and help out where we can.
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Offline you eat wafflesTopic starter

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Re: General questions (newbie)
« Reply #2 on: February 20, 2010, 06:03:28 PM »
I am looking at makeing basic ground rovers (I want to make one with tracks attatched to a platform and maybe put a servo controlled camera on it later) can I use that one I want a little expansion room). Thanks

Offline RobotBits

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Re: General questions (newbie)
« Reply #3 on: February 21, 2010, 03:08:07 PM »
OK, great .... there is already a thread discussing tracked chassis options at:

     http://www.societyofrobots.com/robotforum/index.php?topic=10395.0

So have a look at that first.

Once you have chosen your chassis you need to choose a motor driver with an R/C interface that is capable of delivering enough current to your motors. You can't really go wrong with the 'Sabertooth 2x5 R/C' from dimension engineering which will deliver 5 Amps to each of your motors. If necessary Dimension also do higher rated drivers. For more details visit:

    http://www.dimensionengineering.com/Sabertooth2X5RC.htm

Next you'll need an R/C transmitter and receiver. I'm not familiar with the one you mentioned in your first post but it looks like good value and should do the job just fine. 

Finally, as you have spare R/C channels you can easily add a pan & tilt camera mount. There are a few of these around from different manufacturers such as Lynxmotion. For more details of the Lynxmotion mount visit:

   http://www.lynxmotion.com/Product.aspx?productID=287&CategoryID=61

I hope this helps ... have fun!

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Offline you eat wafflesTopic starter

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Re: General questions (newbie)
« Reply #4 on: February 21, 2010, 08:45:32 PM »
Do I need a driver? are they hard to use? I want to buy things now that have plentty of more room for expansion later would this extra $15 help at all? http://www.dimensionengineering.com/Sabertooth2X10RC.htm

it doubles the amperage. I guess I don't know how many amps a descent size motor draws.....

These drivers are just for the motors right? what do I need for servos? are the 3 cables with the 3 wire connectors on them, connected to the reciver?

I hate to be the new guy and ask what is needed electronically and electromachanically to make an r/c rover but....... my understanding of it is I need a transmitter, a reciver on the robot connected to a motor driver which is connected to a battery, and a motor? what about servos?
Thanks I appreciate your help.

Offline RobotBits

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Re: General questions (newbie)
« Reply #5 on: February 22, 2010, 06:02:53 PM »
You need to match your driver to the motors in your chosen chassis. Once you've decided on your chassis the current requirements of your motors should become much clearer.

Always size you drive so that the peak current of the driver is sufficient for the "stall current" of the motors as this is the peak current that the motors require if/when the motor stalls in the event of a collision. Similar high currents are also seen at start-up and during quick changes in direction.

The driver discussed above is only for the main motors - the servos will connect directly to the R/C receiver. The power for the servos will also come from the receiver which in turn comes from the battery.

The best option here is to use the BEC "Battery Elimination Circuit" built into the Sabertooth driver, this will provide power to the receiver and servos from the main battery that is used to drive the motors - eliminating the need for a second battery just to power the receiver and servos. Full details of how to connect things up are in the Sabertooth manual.

Have fun ....
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Offline you eat wafflesTopic starter

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Re: General questions (newbie)
« Reply #6 on: February 22, 2010, 10:26:29 PM »
I would build one and scavange the expensive parts such as the motor driver for the next one, can it hurt to have the extra 5 amps per output?

Offline SmAsH

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Re: General questions (newbie)
« Reply #7 on: February 22, 2010, 11:14:43 PM »
can it hurt to have the extra 5 amps per output?
Nope, its a good thing to have some room (:
Howdy

Offline you eat wafflesTopic starter

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Re: General questions (newbie)
« Reply #8 on: February 22, 2010, 11:27:52 PM »
Ya I'm not exactly the richest kid on the block,I can't afford to have an arsenal of expensive robots; I don't want to buy a new driver for every robot. Oh do I need this if my first robot is gonna be under like 5 lbs.? I want to start in the ant-beetle wieght class. I want it to be semi powerfull terrain wise, I think I'm going to buy a cheap chassis kit Like this one http://www.robotmarketplace.com/products/0-70108.html as my first rc robot (I would upgrade to a double ger box and put a reciver on it, I plan to after that build my own with better treads and made for beaten paths in the woods and stuff( prolly more than 5lbs) do I need this driver? Thanks

Offline RobotBits

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Re: General questions (newbie)
« Reply #9 on: February 23, 2010, 04:53:40 AM »
If your going for a lightweight chassis, another option is to replace the motor(s) with 2 continuous rotation servos.

These can be connected directly to the R/C receiver so there is no need for a motor driver at all!

Servos also have lots of torque - great for driving over obstacles!  ;)
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Offline you eat wafflesTopic starter

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Re: General questions (newbie)
« Reply #10 on: February 23, 2010, 07:37:56 AM »
hmm I will have to pick up a few of those ;D but I think on the next one I make I want it to go kinda fast and have a little bit og a bigger motor. Do I need the driver even for these little guys? http://www.robotmarketplace.com/products/0-COPAL50-SH.html
http://www.robotmarketplace.com/products/0-RM3.html

This is the one I will be useing because it's made for the treads http://www.robotmarketplace.com/products/0-70097.html Do I need a driver for this?

I want to also get a good starter battery that I can use on general sized robots so I think the most I am willing to put down for a battery is around $50, I think I will just get the largest NiMH I can get will this one work? http://www.robotmarketplace.com/products/0-TRI20134.html
Or this one? http://www.robotmarketplace.com/products/0-VNR1547.html
Which on would you take? Again the idea is for me to buy things oversized right now instead of buying more stuff later.

I appreciate all of your guys's help. :)

Offline RobotBits

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Re: General questions (newbie)
« Reply #11 on: February 23, 2010, 08:27:19 AM »
Any standard brushed motor (such as those you list) will require a driver if you want bi-directional control. All the motors you suggest will be OK with the 2x 5Amp driver discussed earlier in this thread.

As for batteries, for general use I would tend to keep a little 'headroom' and use a 7.2V battery - as your motor/gearbox will tend to last longer. If you need to squeeze every last ounce of power out of the motors go for 8.4V.
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Offline you eat wafflesTopic starter

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Re: General questions (newbie)
« Reply #12 on: February 23, 2010, 04:03:46 PM »
Ok sounds good, 4600mAh is good right, any little robot will run for an hour or 2 right? I have heard that I can't use the same battery for the reciver as the motors; is this true? or should I just throw a few larger capacitors (like a 220uf 25 volt electrolytic) between each motor? Or do I have to buy another pack? also I can't spend a ton on a charger (like $20 or lower) because of all the money that the battery drains. any recomendations, oh also can Nicad chargers also safely charge Nimh batteries? Thanks
« Last Edit: February 23, 2010, 04:12:01 PM by you eat waffles »

Offline RobotBits

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Re: General questions (newbie)
« Reply #13 on: February 24, 2010, 02:54:30 AM »
With batteries, the higher the capacity the better but do not skimp on the charger. A better charger (usually slightly more expensive) will make your batteries last longer - do not continually use a cheap fast charger as this will kill them quickly!

Check out the spec' of the charger to see if the charger is designed to work with NiMh - again using a charger that is not designed for NiMh will kill a NiMh pack quickly.

You can use your main batteries to power the receiver and servos as long as the motor drive has "BEC" battery elimination circuit.

RobotBits - Robot kits and components for fun and learning!
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Offline you eat wafflesTopic starter

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Re: General questions (newbie)
« Reply #14 on: February 24, 2010, 08:02:08 AM »
Whats a BEC? (what does it do?) can I buy it or should I make it? oh I was also thinging of useing a switching reg by dimension engineering. can that be put in too? how does it know when to switch on and off?

 


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