Robot Pet

Hi,
I am new to robots and this is my very first build. I am aiming to build a 4 wheeled rover that zooms around the house. So far I have chosen the sensors, micro controller, motor controller, motor, and wheels.

robotshop.com/vex-omni-wheel.html

Those are the wheels I want to use. The only problems is that the centre ring of the wheel is1 square and my motor has a circular shaft (robotshop.com/productinfo.aspx?pc=RB-Ban-239&lang=en-US)
Is there any way I could attach the wheel to this motor? Or will I have to get a new motor or wheel altogether?

Another Question, on tiled surfaces, will that omni directional will have enough grip on the surface to move properly or will I have alot of wheel spin?

Thanks,
Rohan

Hi,
There is a final problem,
My bayteries are 12V and my sensors run at 5v each, because I only want one set of batteries, I chose this vvoltage regulator (robotshop.com/en/lm78m05-voltage-regulator.html), is this a good voltage regulator? Is there anything else I need for this voltage regulator to work?

Hi,
I provided a summary in my last post…

Is there anything else I need to add?

Awesome, thanks for all your help!

Well,
The 5th motor is really just in case I the differential drive system doesn’t work exactly how I want it to. Because this is my first robot build, I only have a slight idea how well it will suit my needs. If it doesn’t exactly suit my needs, I will put a wheel at the back of the robot, and use some sort of servo motor to turn the wheel left and right, therefore steering the bot. That is only if the differential drive system does not work…

Apart from that, I am running an Arduino Uno Microcontroller, 2 or 4 Devantech SRF02 UltraSonic Range Finders (robotshop.com/en/srf02-ultrasonic-range-finder.html)…

I decided I am most likely going to build the chassis myself, as I can build it to better suit my specifications. The wheels on this chassis wont be omni directional, and their size will most likely be 100mm

Finally,
I will be running these batteries (robotshop.com/en/bat-06-12-0v-2800mah-ni-mh-battery-pack.html)
, and I will be using this charger to charge them (robotshop.com/en/nimh-nicd-smart-charger-1025.html)

That is pretty much everything that will be going on this robot.

Ok, so what batteries would you recommed I use?
I would like the robot to last a fair amount of time.
Also, do you know of any omboard chargers I could use?

So when looking for a battery, I just have to get them to suit the motors voltage? Or do I have to take other things into consideration, such as sensors, and microcontrollers?

My motors nominal voltage is 12v, and im running 4 of them.

robotshop.com/en/bat-06-12-0v-2800mah-ni-mh-battery-pack.html

Would this battery pack be best suited to run the whole robot?

So if im running sensors and a microcontroller, and maybe a 5th motor (for a turning wheel at the back) will I need anything extra?

Well I was thinking of using lipo batteries, simply because of their high capacity.

robotshop.com/en/lipo-energy-shield-arduino.html

or

robotshop.com/en/seeedstudio-usb-charger-power-booster-lipo-rider-pro.html

would this charge the bot effeciently??

Hi Sorry for the late reply,

I have been considering some other options. It would be fantastic if the robot could zoom around and make some good curves, and I don’t really think omni wheels can create such curves (Please say so if im wrong!!!).

As for which omni wheel set to choose. As I said I am really new to all this and have no idea how much the average price for a single omni wheel is. I am also not too sure about the weight, although I plan on using either one of these 3 pre built chassis’ (
robotshop.com/4wd1-robot-aluminum-kit-2.html
robotshop.com/lynxmotion-a4wd1-autonomous-rover-kit-botboarduino-2.html
robotshop.com/dagu-4wd-thumper-mobile-platform-black-75-1-2.html)

For such sweeping curves I was thinking of adding a wheel at the back that is turned left or right by a motor. If you reckon this would work and effectively turn the robot, how would I go about attaching it to a motor? I am guessing I need to get a Hobby Servo Motor, but what else would I use?

Thanks soo much in advance

Rohan

Hi,

Are there any omni wheels which are cheaper??

Thanks,
Rohan

Hi,
Sorry for constantly changing my ideas, as I said I am really new to robotics. I was thinking of running this outdoors as well, because to some the idea of a dog chasing a medium sized robot around the house may not seem too appealing. Would omni wheels run affectively outdoors or would I have to rub my own steering system?

If I need to run my own steering system, how would I go about doing it?

Thanks,
Redmug

So, you mean both wheels spin at the same time, and then to make it turn, one set of wheels turns slower than the other?

Would this be the best way to achieve a turning system?

The problem is, I want this robot to be dynamic and fast in its turns. I needs to be able to change direction quickly, thays why I was wanting to go for omni wheels at the start. Is there any turning system like the omniwheels that can be used outdoors?

Would something like a caster work?
How about a 3 wheeled system?
I need a steering system that is suitable for both indoor and outdoor environments. I read that differential steering is great for outdoors, but can have its flaws indoors. I also read that car type steering is great for indoors but can have its flaws outdoors.
youtube.com/watch?v=uaT7M3Nwj7c - Something like that would be perfect! Is it possible to get that kind of technology? Would casters do pretty much the same job?

Hi,
I plan to use 4 of these motors (robotshop.com/banebots-rs-555-12v-7750-rpm-brushed-dc-motor.html)
Will that be able to turn quick enough?
You have to imagine a dog chasing this thing around. The bot sees and obstacle, and must be able to change direction quickly, before the dog gets it

Hi,
I used this tool to find my motor. Are you sure 30 oz in of torque per wheel is not enough?

With a 4.1 gearbox ratio, what would my new torque and rpm become? The problem is, I need high rpm for high speeds, but I also need torque for quicker takeoffs and better performance outdoors. Will the rpms after applying the gearbox still be enough to generate speed that can outrun a dog?

Ahhh, I understand now,
Can you recommend a good 4:1 gearbox, or could I even go for a higher ratio? Maybe 6:1?