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"GB"
The GearBox Bot

Last Update: 09/14/12
Chassis & Drive System | Brains | Sensors | Electronics | Other

GB2 - The New Plan

Overview / Goals & Objectives

This old base has been around a VERY long time having never actually been "alive". Recently my interest has once again revived in putting some type of bot together but now it's more about a mobile remote control platform than autonomy or some great brainy system.

With that in mind the GB base seems to be quite useful for a Netbook based remote controlled platform. Something simple with a camera or two, left/right/forward/backwards control, and just plain fun to drive from anywhere in the world. It would be very nice if after running a drive up charging base could be deployed allow the bot to be recharged remotely by driving up to the dock. That would keep it rather hands off once up and running as long as I get it back to it's base before the motor or PC batteries died.

I could use one of the other bases or even one of the MANY radio control cars / trucks we have around here but I'm just still kind of fond of this little gearbox and want to see if it will work for what I want it to do. So read on to see how/if this comes to light.

News and Updates

  • 09/13/2012 - Giving Up
    Every was mounted, tested offline, and functioning but the servo board would consistently hang and go away. This continued time and time again and I finally moved the board to the full LT Bot platform and it all works without issues SOOO... GB is dead again for now.. :-(
  • 09/12/2012 - Updates on motor drivers, battery

Chassis & Drive System

Actually the base will really be the same as the original intent in the "Old Plan". Using the GearBox (GB) chassis as a platform, a tail dragger format, and the old relay motor control board (for now at least) to make a borrowed Netbook move around via remote control.

Here is the old text from the old description, but it's still applicable:

On "GB", the chassis and the drive system are all in one. The gear box IS rather interesting... it is a dual motored unit with a magnetic coupler that allows the platform to run straight forward if both motors are running. If only one motor is running, the magnets will unlock allowing the unit to turn like a normal two motored robot. I found this little box in a surplus catalog for $6 many years ago with the idea of building a robot on it. Now I realize it is a gearbox from a Big-O-Trak. When I ordered it, however, I thought it was much bigger and much stronger than it turned out to be so the scale of the robot has come down.

The Brains

The "new" brains of GB will be a Netbook PC. When the original plans of my LTBot using a full sized laptop didn't really work out due to the heavy weight of the the old laptop I had available, I noticed the new Netbook sized systems a few years ago as a viable option. They are cheap, powerful enough in most cases, and have pretty good battery life. Plus they have at least one built in webcam which can be useful for a remote controlled platform. Add to that the ease of programming in a PC environment (at least for me) and the chances of something maybe working go up quite a bit.

Of course by now the LTBot chassis has been stripped of most everything except the chassis and motor and isn't really ready to run. Plus it's quite heavy itself being aluminum with large motors and feedback sensors. SO the idea came up to use the old GB box and see if it will work with the "new" netbook concept.

Software

The PC will run a simple BASIC programming language staring with JustBASIC to provide an interface for the controlling user.  JustBASIC appears to be rather easy to code in, can use graphical windows with ease and no GUI required, and supports RS232/USB use. The main purpose of the local app is to read the users input via buttons on the screen (see remote control below as to to get there), send the RS232 control signals to the servo / output controller and read back some basic sensors / status information for drive battery voltage, distance to objects, etc. Simply stuff without a lot of autonomy code loading it down.

Remote Control

Originally I had wanted to somehow control a remote control bot via a web server running on the local machine displaying the cameras and providing control. I'd thought of other options like some client / server piece but it's way over complicating it. With the advent of free / low cost remote controlled PC software like LogMeIn, it is much easier to just design the software locally and control the bot via the remote control service. LogMeIn even provides an excellent dashboard showing analytics such as memory, CPU load, drive space and more about what's going on in the PC that's controlling the bot. Pretty good for free. Security is handled as well with the LogMeIn account first and then having to log into the Bot PC as well before doing anything. One additional nice thing about using standard connectivity such as WiFi or Cell for the netbook is that the bot can really go anywhere it can drive when running from a cell signal. Upgrade the platform and it could be running wild across the fields if desired... for a little while anyhow.

Sensors

Webcams

Rear / Built In

Honestly a camera appears to be the best sensor and maybe the only needed for a remote control platform that isn't off on Mars or something with huge lag times. It provides a natural view of the remote environment and is intuitive to use. Current plans call for the Netbook to set on top of the mobile platform with the screen facing towards the back and use the integrated webcam as a rear view / interactive view. Maybe one can swing the robot around and have a video conference with the dog or something... IF the Netbook has enough power to Skype that is.

Front Cam

An additional low end Logitech webcam is mounted up front and is planned to be a little more interesting. Using an RC servo will allow up / down movement of the camera for better positioning. The robot can turn left / right so no real need to pan, just need the tilt option to look down at the floor and up at people.

MAYBE I will add another servo to actually move the Netbook display back and forth to allow looking UP or down for the rear view but that really isn't likely needed. A wide angle webcam may be more beneficial here but I'm running with what I have available for now, my $9.99 Logitech.

Webcam Software

For now at least I am just using the ability for Windows Explorer to display USB Video Devices. It seems to do a fine job, has a good frame rate, and isn't using much CPU power. I had originally planned on using third party app to read/display the camera but running two copies slows things down on the little Atom powered PC. So until something better comes along the basic view seems to work.

Someday / Maybe Sensors

Sonar Distance

I do have a LV-MaxSonar EZ1 range finder sitting in the parts bin that could be deployed for some ranging experiments. It's a narrow beam version so it may need to be mounted on a scanning servo to get a true picture of what's out there. Output is RS232 TTL so the Netbook could be reading the RS232 data back through the servo controller for avoidance enhancement.

IR Distance

I also have some IR distance sensors that provide an analog output based on shorter distances that may be useful for the blind spots around the front edges of the platform. Not sure they are needed and they will not be added unless I run into issues.

GPS Sensor

Needed? Wouldn't think so with this but maybe if running off cell connection and a larger platform. Could be useful if I decide to add some more autonomy to it. Pretty easy to so, USB GPS or RS232 converted, read the NEMA stream, update a Google map in a browser or something? Guess you could log the results as well for the heck of it.

Electronics

Motor Control

Electronics in general will be pretty limited based on current plans. A 4 x 1.25/1.5 AA battery pack for driving the motors and servos and likely the basic logic, a relay controlled by the PC to engage the pack for the controller and motors, the relay based motor controller board, and maybe a USB hub to connect other devices in the future.

09/12/2012 Update
I changed from the relay option to two standard RC Car speed controllers from ebay I found for $10 each. New, China made, but quite workable solutions. Provides easier speed control via the servo control board AND provide a Battery Eliminator Connection (BEC) to drive the other servos on board.

Also updated to a small 4.5v lead acid battery to power the motors and servos. The AA pack worked and was lighter but it just didn't have the run time I would like to have out of the bot. This battery will run much longer.

System / Servo Control - Input / Output

For Input / Output a Pololu Mini Maestro 12-Channel USB Servo Controller is planned as the controller channels can be used as wither Servo control out, digital out, digital in or even analog in. It's small 1.1" x 1.42" and can handle both USB or TTL RS232 control inputs. It even converts the USB 232 to TTL for chaining to other devices. I've used an older Pololu controller on my homebrew Pan/Tilt Cameras in my home automation systems for years without problems. The logic on the board is powered by the USB port so only Servo power is needed to make it work.

Charging Base

Once running this is really something I want to build/deploy as it will allow the robot to stand alone without someone having to plug it in to recharge it. It's not going to find the charging station itself but I plan on building a good drive up station with some spring loaded connectors to charge the laptop and the base server/motor battery pack. Using the front camera it should be somewhat easy to track into some connectors on a base. As a backup I plan on building a triangulated ramp that centers the bot up as I drive towards the bullseye target on the base. That's the goal at least.

Other Considerations

Evil Stairs and Steps

Unfortunately (or fortunately depending on what you like/want) our home is not all one level. The living room, where the bot will likely live, is sunken in with steps going into the Kitchen/Dining and the hallway to the rest of the house. How to get up/down this step has not been determined yet. Thoughts of a pop up ramp tied to the Home Automation system have come to mind but keeping it looking OK is the challenge. Of course a bigger platform and bigger wheels can solve this or a platform with tracks but that's not what I'm looking for. Time will tell.


The Old Plan - Now Obsolete 

Last Update was 11/2002

Chassis & Drive System

On "GB", the chassis and the drive system are all in one. The gear box IS rather interesting... it is a dual motored unit with a magnetic coupler that allows the platform to run straight forward if both motors are running. If only one motor is running, the magnets will unlock allowing the unit to turn like a normal two motored robot. I found this little box in a surplus catalog for $6 many years ago with the idea of building a robot on it. Now I realize it is a gearbox from a Big-O-Trak. When I ordered it, however, I thought it was much bigger and much stronger than it turned out to be so the scale of the robot has come down.

Brains

Nothing for now. I plan on using my Stamp2 board on this one.

Sensors

None for now. IR Sensor and bumpers planned

Electronics

Relay motor driver board. Basically a relay version of an H Bridge, it has three control lines, Left Motor Direction, Right Motor Direction and Go/Stop. The board takes three bits to drive; Left Motor Direction, Right Motor Direction and Go/Stop.

Current GB2 Setups

GB2 Ready to Test
Ready to Test Mobile

iPad Remote Control View
iPad Remote View

Front Camera Mount Detail
Front Camera Mount

Drive Up Charge Plates and Mount
Drive Up Charge Plans

OLD GB Setups

S_gb-2.jpg (13614 bytes)
Botboard 1 up front, relay board, original vision board.
S_gb-1.jpg (13462 bytes)
Same shot, right side.
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Rear view of bot with BS carrier board. The board mounted is where BS2 will reside when on the bot.

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Left rear - Relay board is mounted, battery too. I guess this *could* be the front???