Omnibot 2000 Best Way To Move The Wheels

 
#1

Im starting my Omnibot 2000 conversion. I took it apart and when I got down to the base where the wheels are I started thinking about the best way to make the wheels work. I was first thinking of gutting the wheel bay and attaching four 360 deg. servos one to each wheel and that would be it. Now when I opened EZ-Builder to add a Modified Servo Movement Panel it only lets me control 2 servos. My first question is, can I splice the two left servo's to one 3 wire connector and plug it into the ez-b under d0 and do the same with the other 2 on the right and plug it into d1 and it will work?
I'm open to suggestions. I'm also concerned about the weight on the wheels and if the standard 360 servos (x4) would be strong enough to move the bot around at a nice speed. I gutted it really good, removed all the 80's tech wires,tapedeck etc. to make room for the 7" android tablet for the front display. So if anyone can help I would be so grateful. thank you in advance. Im also cgi artist so if anyone needs and interface gui graphics and animation hit me up. The 7" tablet that will be installed on the front panel of the omnibot will have a cgi version of the orignal look. I enclosed a pic of the gui WIP.
User-inserted image

User-inserted image

#2

When I started Melvin I was looking at using Modified Servos to control the wheels, then I realised that Modified Servos probably wouldn't be the best thing to drive a robot of his size - he is smaller than the 2000, he is a Hearoid base which is an Omnibot 5402 with a different head basically.

Your best bet in my opinion is to use a H-Bridge to drive the original motors (or upgraded motors).

However, if you really want to try Modified Servos, look at Testbot's project, he uses 4 Modified Servos controlled with a custom Movement Panel which has script commands to move four servos. However you can also combine 2 servos to one port if you wanted to do it that way too.

P.S. I love those front panel graphics. If you had come on 6 months earlier I know I would have used them on Melvin.

#3

Hello , I would love to see more pics of your build. So as far as moving around I highly recommend just keeping the original gearbox. Modified Servos would need to be very high torque to move you robot. He weights In at about 18 pounds when you remove the main board, tape deck and rear weight. My Omnibot will weight in at 55 to 60 points and I have the original gearbox and upgraded the motors themselves. Then just keep it in low gear for the highest torque and your Omnibot will move fine. Be sure to lubricate your gears and you may want to cover it with dynamat to keep the noise down.

#4

Here's low gear example which is the slowest on 12. I used 40 pounds of weights on the base and added maybe 5 pound between the wood , fiberglass and bigger motors.
https://www.youtube.com/watch?v=viq18XPdSIg&feature=youtube_gdata_player

#5

High gear video. This is what I recommend to use then just use pwm to dial back speed. When its not running wide open its not as loud either. https://www.youtube.com/watch?v=nqclPdG5FcY&feature=youtube_gdata_player
https://www.youtube.com/watch?v=Q5w6XiU_3Ho&feature=youtube_gdata_player

#6

I could give you a pair of these motors that are higher torque at the same voltage. They have the same shaft I believe as your existing ones meaning you can pull your pinion off the originals and swap them. I'm happy to send you a couple.
User-inserted image

#7

ok I appreciate the really fast info you guys. Now, I like the H-bridge ide as so I can use the original motors. My question is...How does that work exactly? I know the original motors have only pos and neg wires. The servos have the same with the 3rd wire being the signal wire. So how does this work? Also here are some early picks of the build and mock ups.
User-inserted image

User-inserted image

User-inserted image

#8

Have a look through the support pages in the menu at the top, there is plenty of info on all controls there.

This is the H-Bridge. I'm sure that explains it as well, if not better than I could.

EZ-Builder has native controls for H-Bridges so it is very easy to use. There are also many examples for using them. I would say most, if not all of the larger projects in the showcase use a H-Bridge.

Basically, the motor connects to the output of the H-Bridge. The EZ-B to the input. Depending on the state of the signal wires (high or low) will vary the motor behaviour. If you want to get very basic, think of it as though the H-Bridge sets the polarity of the motor. Connect a motor up to a battery one way and it spins clockwise, swap over the terminals and it spins anti-clockwise (counter-clockwise), disconnect and it stops.

#9

And FYI, that is one good looking robot!

#10

So is some of your pictures edited to show how you want the concept to look? I'm a big fan of the omnibots so I'm sure I will follow this closely. Smile

So far most people who did a Omnibot 2000 used a L298N Hbridge which is sold in the eZ robot store. As long as you keep your robot very light and give the motors a 12 volt diet you should be able to use the L298N. However you sound like you are going to be adding equipment so you may want to consider a 2x5 sabertooth 59.99 http://www.dimensionengineering.com/products/sabertooth2x5

This is recommended for robots up to 25 pounds which should be right up your alley. We have tutorials to hook them up when you get one.