| Main page for Farm Robots Robots
and the Environment
Robot
Features About the Author
Invest In Or Donate to Farm Robot project |
| Parts and Expenses Budget Proposed Development Plan Robot Related Links Optical Encoder Pattern Generator Incremental Optical Encoder info |
 The Box Robot testing platform project. Construction started: April 2009 Inspite of not having enough money to build the first prototype farm robot, I took my lay off from my last job [Nov 2008] as an excuse to cash in my RRSPs that I had accrued with the former company, and I was able to purchase enough parts to build a very simple robot. This is not a farm robot, but it gives me the platform [simple robot] in order for me to learn how to use the electronics, and to start the farm robot software. Some of the parts I purchased, or had already purchased, were 3 PC104+ embedded computers, Wireless LAN kit for PC104s from Sensoray, Frame grabber for PC104s, simple video camera board from ebay, AMP Bridge2000, Electronic Compass, GPS Unit from the RobotShop, PC104 Power Supply unit, and the cheapest simple two wheeled robot body frame [+ 2 balance wheels] that I could find - from Zagros Robotics. I chose to buy a partial frame in order to save time. There can be a lot of design considerations for a robot body, and I was more interested in moving ahead with the project as fast as possible then with determining which motors, gears, brackets, etc to use for a simple two wheeled robot. My only consideration was that it was big enough to carry all the parts I wanted, and thus carry enough weight. I chose the 16 inch by 16 inch Zagros frame with the gears for the slowest speed. I'm not interested in speed. And in fact I wanted it to be slow as a way to protect it from damage during testing. With this simple robot I will be able to develop the skills that could help me find a new job, but more importantly start some of the key systems for the real farm robot. Another source of some of the parts was WinSystems. I chose some of the parts and companies based on their parts having sample software and/or drivers for the real time operating system QNX [aka Neutrino]. However, to start with I may not be able to use this RTOS. |
| Stages |
Stage
description for development of ROBOT/ROV [Remotely Operated underwater
Vehicle] hybrid. (Note: ROV does not normally refer to out of water
robots.) |
| I |
Development
of a Robot/ROV hybrid version of the robot to develop
some of the systems to get the robot going and to have the basic
concepts "made into a
reality." [Most of the 1st year.] |
| II |
Semi-autonomous
version. Introduction of some of the automated logic/programming for
the Robot/ROV to actually do some of the work on its own. [End of the
1st
year.] |
| III |
Autonomous
version. Indefinite process towards a robot that can work on its own to
keep the use of pesticides and herbicides to a minimum. Only
intervention required is maintenance and repairs. [Continuous process -
forever.] |
Link to Box Robot Images and Structural Progress [bottom of this page]
| Month |
Achievements |
Costs |
Other |
| Pre-Start |
Testing of the various
parts on their own. |
||
| Month 1 |
Software: Electrical Systems: Mechanical Systems: |
||
| Month 2 |
Software: Electrical Systems: Mechanical Systems: |
||
| Month 3 |
Software: Electrical Systems: Mechanical Systems: |
||
| Month 13+ |
|||
| Continuation into
the future for new designs and features. |
 |
 |
| The Box-Robot testing platform.
This is a slightly modified Zagros Robotics body. I added the perforated metal panel since it will allow me to add parts just about any where I want. Plus it will act as a static discharge plate while I'm working on the electronics. I guess I will have to add a grounding wire to it. The space between the plate and base also allows me to fit my hand between them, to hold screws and bolts in place, while I'm mounting parts. [April 27, 2009] |
Here you can see the motors and
the optical encoder disk that I am planning to mount to the system here. At the moment I'm waiting for one electrical component for the test circuit for testing the optical encoders on one of my breadboards. The optical encoder disk is actually a CD that I printed a black & white pattern on. Its a 48 segment disk since this works out to about one pulse per centimetre. Here's a handy page to generate optical encoder patterns, I did my own though before I found this page. Busyhtail provides a variety of options for the pattern to be generated. [Note there was a problem with the disk. See |
 |
 |
| There was not enough space
between the wheel, the screw that mounts it to the shaft and the gearbox to put the optical encoder disk between them. So, I had to mount the disk on the outside. This will actually make it easier to mount the sensors since I will have more room and can hang the circuit board down from the base. Note the large black box in the middle of this robot base. It would be nice if Zagros would offer a longer shaft for mounting the optical encoder disk between the wheel and the gearbox. Also they provided only a single pair of sensores, but quadrature encoding requires a pair per wheel. So, it would be better if they sent four of them. [May 2, 2009] |
The black box will hold a 12
volt gel cell rated at 7.2 AH [Ampere Hours]. Zagros provided two - 4 D cell battery holders to provide 12 volts, but the cost of me getting 8 rechargeable D cells, plus a new charger is not worth it.My current normal battery chargers only hold C cells and smaller. Its cheaper to buy a 12 volt gel cell and mount it to the bottom. Luckily I purchased the 16 inch by 16 inch version which has enough space for a 12 volt gel cell underneath the body. The 12"x12" would not have allowed me to fit such a battery under the body. Here I've mounted a heavy plastic box to hold it. And the box fit between the balance wheels with about 1/4 inch to spare on each side of the box. I would recommend that Zagros add a 12 volt gel cell battery holder to their list of options. As having the battery here not only makes for more space on the top of the main base, and thus more room for circuitry [etc] it also lowers the center of mass for stability. |
 |
|
| I ended up finding a Stepper
Motor test circuit that allowed a 1 MOhm linear pot to be used to control the speed of the stepper motor. I chose a stepper motor to test with as I had a few lying around. Stripped out of old floppy drives. Finally I had a use for them. :) This required the use of a ULN2003 chip. I found out more about this device from Electronics Schematics for Hobbyists web site. But I found the original test circuit from Basic Stepper Motor Driver circuit before I even knew about this chip. [May 11, 2009] Click on the following LINK for an image of the schematic for the stepper motor test circuit. This is a test circuit to control the motor by using a dial, really a linear potentimeter. The actual control of a stepper motor by a computer would not use this circuit. Instead you would use the ULN2003 chip differently through your parallel port or some similar circuit. |
I found a circuit to drive the photomicrosensor
on one of Omron's pages about photomicrosensors in general. This is a pdf and it should load into your browser automatically. I was not able to get the SY310 to work properly, plus its leads are too short to be used well on a circuit test board. I then tested the original QRB1134 [data sheet courtesy of Seattle Robotics Society], which I don't like because it won't sit flat on a circuit board due to its design. This also did not work. I then considered perhaps the problem was the disk and paper I was testing. And sure enough it was, I had never tested my finger, and yet my finger was working with the infra-red sensor. Oddly enough it saw the white and black regions of the CD as having the same infrared reflective properties, and even the clear plastic disk you get when you buy a pack of CDs or DVDs as being just as reflective as even the white and gray paper I was testing with. All these materials reflected infrared in the same way. The solution turned out to be to re-paint the optical encoder pattern with Testor's Flat Black paint. This worked very well, and both of the photosensors now work properly. [May 14, 2009] |
| *Currently studying for a job
interview. |
|
