DESPERATELY Need Help for creating a wireless sumo robot

[rippa911]

HI there. I'm new to robotics. I started research for a RC controlled sumo bot a while ago and I'm having lots of questions.
 I live in a third world country and its really hard to get components and stuff.
So I've decided to compete in a state level RC controlled robot sumo competition.
I've decided not to use a microcontroller to keep the cost down and its not really required (amirite?)
Anyways here are the rules:

Objective

To design and build a robot which pushes another robot off from the round table of diameter 1.5 m. The robot can only push other robot by contact and not by impact.

Machine Specifications

1. The Robot should fit within a dimension of 20 cms by 20 cms by 20 cms.
2. The maximum weight of the robot should be within 2.5 kg.
3. The robot should be controlled by a wireless remote.
4. Principles of capacitance and magnetism are to be avoided.
While designing the robot, flames, smoke or any liquid or chemical cannot be used as defensive mechanisms
5. The maximum volts at any point should not cross 12v.
6. No external power supply is allowed
7. A description of machine should be sent and verified before building to xxx This e-mail address is being protected from spambots. You need JavaScript enabled to view it before xxxx.
8. The Robot cannot fly in air.


Judging Criteria

1. Time required to defeat the other robot
2. Design
3. Cost

So here are my question

Open questions:

I can't find a RF remote controller for this thing. Is it a good idea to use these and create my own remote control?
http://triindia.co.in/shop/product_info.php?cPath=44&products_id=72
http://triindia.co.in/shop/product_info.php?cPath=44&products_id=73
http://triindia.co.in/shop/product_info.php?cPath=44&products_id=100

Will I be able to control the speed with which the motor goes?
Will I be able to fully utilize differential drive so that I can actually MOVE while turning?
What happens when I push two or more buttons on remote controller simultaneously?
How many channels do I need?
How can I be sure that the remote controller does not interfere with the opponents robot and vice-versa?

[cooldog]

Will I be able to control the speed with which the motor goes?
Will I be able to fully utilize differential drive so that I can actually MOVE while turning?
What happens when I push two or more buttons on remote controller simultaneously?
How many channels do I need?
How can I be sure that the remote controller does not interfere with the opponents robot and vice-versa?

you have to get speed control, or use servos: there slow but strong
you can use differential drive but i don't know what you mean by moving while turning
those actions will be preformed depending on what you connect them to
two channals is enough for the wheels but you need more if you want it to do something other then driving
you have to get a crystal and make sure your oppent doesn't have the same one or get a couple and change them


look at this
http://www.societyofrobots.com/robot_sumo.shtml
it uses two servos but it is controlled by a microcontroller buty you can easily convert it to RC

[HyperNerd]

That encoder/decoder chip looks like a pretty good thing to have lying around - I might see where I can get some of those here in the UK... 8 inputs/outputs plus encoding/decoding on 1 chip !

Building your own remote control is a good idea, as you can configure it to whatever you need for the project. However, if you need speed control, you will have to go with buying a remote, and use servos on the robot. This option is more expensive, but will allow you greater control over the robot's speed and direction.

For your remote controlled robot, you could build a remote with 8 buttons arranged in whatever configuration you need; one of the chips configured as an encoder; and an RF transmitter module connected to an antenna. Then have an aerial on the robot connected to another one of those chips, configured as a decoder, with four of the outputs connected to 2 H-Bridges, driving the motors.

To answer your questions:

Will I be able to control the speed with which the motor goes?

Yes, but only if you buy a pre-made controller and use servos (expensive option), or a DC Motor speed controller (even more expensive)

Will I be able to fully utilize differential drive so that I can actually MOVE while turning?

If you mean move one wheel faster than the other so the robot sort of goes in an arc shape, then you will have to use speed control, as if you make your own controller, the motors can only spin forward/backward at 1 constant speed.

What happens when I push two or more buttons on remote controller simultaneously?

If the two buttons are connected to the same H-Bridge and therefore the same motor, "Your circuit explodes into pretty sparks", quoting Admin's H-Bridge tutorial. You can prevent this by buying a remote with joysticks, or making the two opposite buttons on the home-made controller on a 'rocker', so only one button can be pressed at a time.

How many channels do I need?

You will need two for driving, plus one more if you wanted say, a flipper on the front of the robot. Note that on the home-made controller, each channel requires two inputs/outputs, for forward, off and backward.

How can I be sure that the remote controller does not interfere with the opponents robot and vice-versa?

That chip you listed has an 'address' setting. I'm presuming this means that the transmitted data is encoded with that address, so the encoder and decoder have to have the same address for the communication to work correctly. If you connected the four 'address' pins on the chips to a DIP switch, you could configure the address on the day, and change it if necessary.

Hope this helps and good luck at the competition !

 -HyperNerd

PS. I could make a schematic for you if you wanted, showing you how to do the things I have suggested

[Admin]

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

[rippa911]

That encoder/decoder chip looks like a pretty good thing to have lying around - I might see where I can get some of those here in the UK... 8 inputs/outputs plus encoding/decoding on 1 chip !

Building your own remote control is a good idea, as you can configure it to whatever you need for the project. However, if you need speed control, you will have to go with buying a remote, and use servos on the robot. This option is more expensive, but will allow you greater control over the robot's speed and direction.

For your remote controlled robot, you could build a remote with 8 buttons arranged in whatever configuration you need; one of the chips configured as an encoder; and an RF transmitter module connected to an antenna. Then have an aerial on the robot connected to another one of those chips, configured as a decoder, with four of the outputs connected to 2 H-Bridges, driving the motors.

To answer your questions:

Will I be able to control the speed with which the motor goes?

Yes, but only if you buy a pre-made controller and use servos (expensive option), or a DC Motor speed controller (even more expensive)

Will I be able to fully utilize differential drive so that I can actually MOVE while turning?

If you mean move one wheel faster than the other so the robot sort of goes in an arc shape, then you will have to use speed control, as if you make your own controller, the motors can only spin forward/backward at 1 constant speed.

What happens when I push two or more buttons on remote controller simultaneously?

If the two buttons are connected to the same H-Bridge and therefore the same motor, "Your circuit explodes into pretty sparks", quoting Admin's H-Bridge tutorial. You can prevent this by buying a remote with joysticks, or making the two opposite buttons on the home-made controller on a 'rocker', so only one button can be pressed at a time.

How many channels do I need?

You will need two for driving, plus one more if you wanted say, a flipper on the front of the robot. Note that on the home-made controller, each channel requires two inputs/outputs, for forward, off and backward.

How can I be sure that the remote controller does not interfere with the opponents robot and vice-versa?

That chip you listed has an 'address' setting. I'm presuming this means that the transmitted data is encoded with that address, so the encoder and decoder have to have the same address for the communication to work correctly. If you connected the four 'address' pins on the chips to a DIP switch, you could configure the address on the day, and change it if necessary.

Hope this helps and good luck at the competition !

 -HyperNerd

PS. I could make a schematic for you if you wanted, showing you how to do the things I have suggested

Can you please make the schematic for me.  I'll be glad to have it. ..

[arixrobotics]

In a competition where RC robots are used, I think its best to use standard off-the-shelf RC equipments. This is because the organizer might want you to change frequencies so that it won't match your opponents or other robots' frequencies.
Better check it with the organizer.

[HyperNerd]

The schematics are finally done!

Sorry for the long wait, but I have been studying for my Maths GCSE virtually non-stop, so not much free time.

The 2 schematics are for the Transmitter and Reciever circuits. The board file is for the transmitter only. I could not make a board design for the reciever as it will change depending on what you connect to it.

The designs were made in CadSoft's Eagle, which is free for non-profit use. You will need this to view the schematics and board design.

In the schematic, I mention buttons 1 - 8; these are the 8 digital inputs on the encoder chip, and therefore the 8 control buttons for the robot. If you look at the transmitter schematic/board, you will see that I have arranged the buttons in a joypad style layout, as I believe this is the most flexible. Feel free to change it if needs be. So you know which buttons are which, they are arranged like this on both the schematic and the board designs:

        1      |       5
     2     4  |    6     8
        3      |       7

 -HyperNerd

[SmAsH]

wow hypernerd! those look relativly easy to make? have you made one yet?

[Razor Concepts]

Trying to find the actual ICs... here is a promising list:
http://www.holtek.com/english/products/remote_4.htm

[superchiku]

what do u mean 3rd world country dude...everything u need is available and even more...u havent searched in the right place... loook into www.nex-robotics.com, www.robokits.org....and it may be enev available in ur local market so stop complaining and start searching..

[SmAsH]

what do u mean 3rd world country dude...everything u need is available and even more...u havent searched in the right place... loook into www.nex-robotics.com, www.robokits.org....and it may be enev available in ur local market so stop complaining and start searching..

dude, chill out! by 3rd world country he means that they dont have all the things that we have. he mightn't even have a local electronics store. and hes tight on money. superchiku i dont want to sound mean but please leave this guy alone

[superchiku]

look at the site he told...it proves he is from india...and by far i know we got more electronics and robotics store than u can ever need of...

[HyperNerd]

I haven't made one of these yet because I don't have any of the encoder/decoder ICs (can't find a source in UK )If anyone finds a source near UK (France / Germany is acceptable), then please let me know, and I will stock up!

I think I figured out a way to solve the problem of pushing two buttons at once and blowing up the h-bridge. Take a peek at my attached image.
Basically, the two inputs are connected to an XOR gate, and the output of the XORis connected to the bases of two NPN transistors, which switch on the outputs. This could be applied to the reciever circuit I posted, so if you pressed two buttons at once, the robot would stop, not explode.

 -HyperNerd

PS. Razor, good luck with the searching!

[rippa911]

I haven't made one of these yet because I don't have any of the encoder/decoder ICs (can't find a source in UK )If anyone finds a source near UK (France / Germany is acceptable), then please let me know, and I will stock up!

I think I figured out a way to solve the problem of pushing two buttons at once and blowing up the h-bridge. Take a peek at my attached image.
Basically, the two inputs are connected to an XOR gate, and the output of the XORis connected to the bases of two NPN transistors, which switch on the outputs. This could be applied to the reciever circuit I posted, so if you pressed two buttons at once, the robot would stop, not explode.

 -HyperNerd

PS. Razor, good luck with the searching!

Can you please update the layout with the new one? I dont have much knowledge in electronics..

[HyperNerd]

I will, but I don't know if my solution will work yet, so I posted it here to see what other people thought. So far though, no one has responded

As soon as I know that it will work I will update the diagram, but I don't want you to build it to find that it doesn't work.

 -HyperNerd

[Razor Concepts]

Isn't the transistor on the input/output 2 wired the wrong way? If input 2 was high and 1 was low, current would try to flow from output 2 to input 2    Other then that it looks okay.

[HyperNerd]

You're right there Razor...

Must have been lazy and forgot to mirror the part on EAGLE.

 -HyperNerd

[Razor Concepts]

Just got 2 HT12E and 2 HT12D in the mail... got em all on ebay for about 10 shipped. Will see how they do.