Making your own, customized robots have always been a dream for many. I am not an exception to this. Though I could not make robots like those with artificial intelligence in iRobots, I made one which could follow a line. “THE LINE FOLLOWER”. Without any further delay, let me list the steps to make your own robot and showcase it successfully at the competitions. You may also want to look at:
Step 1: Decide on your robot type
Deciding what type of robot to build is the main criteria, before you make a robot. There are various types of robots, which include,
- Line followers
- All terrain robots
- Mobile robots
- Soccer robots
- And the list goes on and on and on…
After deciding what type of robot you want, check for what purpose your robot will be used. For students like me, the most enthusiastic thing is to display the robots in some competitions. And some people do it for fun!! You will have to decide upon that.
Step 2: Get down to your details
After deciding upon the type of the robot of your choice, the next step is to write down the specifications. The specifications include the type of the microprocessor, number of wheels needed, number of gears needed, type of PCB,etc.,
The most common tools that are needed to get your hands dirty on robots is the basic tools. Here are some basic tools that are needed.
- Small screwdriver set
- Needle nose pliers
- Diagonal cutters
- Wire cutters/strippers.
- Soldering iron
- Iron stand with sponge
- De-soldering pump.
- Jumper kit
- Safety goggles
- Digital multimeter (DMM)
- Metal file set
- Heat sink
- Hot glue gun
- Scrubby pads
- Screw, nut, bolt, and washer assortments
- Construction materials (brass and aluminum stock, sheet plastic, expanded PVC foam)
- Resistors, capacitors, inductors
Well, this list doesn’t stop with this. It goes on infinitely depending on your robot type. The list for a basic beginner’s line follower robot will be posted in the next blog.
Step 3: Building your own workshop
Obviously, you don’t need anything fancy to build robots beyond the handful of tools already outlined, and a clean, well-lit, well-ventilated workspace in which to use them. This workspace can be anything from a kitchen table to a corner of the bench in your basement. The bigger the robot, the more space you’ll need, and the bigger and more specialized the tools. But if you find yourself spending a lot of time building bots, you’ll want to consider a more permanent setup and a few more tools that can make your robot building safer, more comfortable, and more productive.
Here are some main items to be considered for your workshop.
- A decent-size workbench or table that’s high enough that you don’t have to slump over it too much while you work.
- A comfortable and adjustable chair or stool. I have a nice drafting stool with adjustable seat and backrest. It has decent padding and even a lumbar support. It was an $80 chair, but I got it at an office furniture sale for $35.
- Plenty of good lighting. A combination of incandescent light (in a swing-arm lamp) and florescent light is ideal. A third light, a magnifying lamp, is even better.
- A power strip with an easily accessible on/off switch, so you can kill the power in a hurry (mine sits on the back of my workbench and is always a quick swat away).
- A ventilation system for soldering.
- Adequate storage. You’ll need plenty of multidrawer parts cabinets and compartment cases in which to store electronic components, as well as small plastic “dump bins” to organize bench clutter, and larger bins (cardboard boxes) for storing big structural components, techno-junk, and so forth. These bins can go on shelves under your bench (if possible), or on storage shelves accessible to your workspace. You can get metal utility shelves at department stores for under $20 a unit.
- An anti-static mat makes a nice, clean work surface, and its anti-static properties helps keep shock-sensitive parts safe.
After gathering all these, now you are ready to give birth to your own robot. Name it as you like.
Step 4: Making yourself ready
Since I was forced to work in a limited time, I made a time schedule first. Like, on which day the robot should reach which stage. I divided my design into various stages like programming stage, circuit designing stage, purchase, assembling stage, testing stage, debugging stage, final checks. I named all these as Milestones. This would be helpful if you are making a robot for a competition.
Make a note of what all stages should be finished at a particular expected time. This would be of much use for you, as you would not miss out any of the important steps while designing your robot.
Step 5: Planning your robot structure
After you have finished all the above steps, its time for you to plan for the structure of your robot. You may use Google Sketch Up designing utility for making a 3D model of your robot. Its really interesting.
- Ready made kits are also available, which I don’t recommend.
- Modify an existing toy.
- Make one from steel or plastic sheets.
- How many does your robot require?
- Type of steering method your robot uses.
- Determine the size of the robot and build the chassis according to it
- Next thing is to determine the shape of the robot.
- You may design it as very simple as in the shape of a car, etc.,
Step 6: Deciding your wheels
The next step is to decide what type of wheel do u need for your robot. The main points about a road wheel are its diameter and the nature of its tread. A larger diameter is better on a rough or uneven surface because the wheel can more easily ride up over ridges and is less likely to get stuck in grooves. Also it allows there to be a larger clearance between the surface and the underside of the chassis.
If the surface is smooth and even, for example the rails of a gantry, small wheels have the advantage of light weight. It is all too easy for a robot design to finish up by being heavier than the motor can drive. Using small wheels helps to avoid this. Tyres help the robot to run without slipping. The simply programmed robots usually start and stop abruptly. This leads to skidding or slipping. We rely on a robot being able to run in a straight line but slipping makes it run in irregular curves. Unless it is continually taking its bearings from a fixed landmark, it soon gets lost. Wheels slip, even when they have tyres, but tyres help to avoid serious slipping.
A recurring problem with wheels is that the hubs of the selected wheels do not fit on to the output shaft of the selected motor. There are no standard diameters. Apart from trying for a different motor or wheels, the solution is to compromise and improvise! A wheel must be secured to the shaft so that it does not work loose and drop off, and it does not slip when torque is applied. Often a friction grip between hub and shaft is adequate, especially for a lightweight robot. If the diameter of the shaft is less than that of the hub, slip a short length of plastic sleeving, aquarium aerator tubing, or PVC insulation (stripped from a cable) on to the end of the shaft. Then push the wheel on to that. Possibly a second layer may be needed to make a tight fit.
If the wheel fits fairly well (so as not to wobble when rotating) slipping can be prevented by wiring the hub to the shaft .
There are several sources of road wheels suitable for robots. Tamiya make a variety of wheels with tyres, including truck tyres and sports tyres. They also make tank tracks, which are sold complete with the wheels to run in the tracks. The wheels and tracks are boxed as kits and sold by hobby shops.
Basically there are two types of wheels. (i) the Gear Wheels, (ii) the Pulley wheels. Its up to you to choose what type of wheel you need. I recommend gear wheels always, since they are much good than the pulley wheels.
Step 7: Choosing your motor
Although motors are electrical and therefore might be a topic for the electronics chapter, they move the mechanical parts so need to be talked about here. The discussion focuses on small low-voltage DC motors. When selecting a motor for a project, one of the main points is its operating voltage, for this partly decides the size and weight of the battery that must be carried.
Motors running on 12V need eight AA cells. These are too heavy a load for a small robot such as the Scooter. The Quester is larger and heavier so needs more powerful motors to propel it. This robot runs on a pair of 12 V motors, powered by a battery of eight AA cells. If we needed maximum power we would use dry cells, but rechargeable cells are more economical. Eight LiMH cells produce 9.6 V, and will drive the motor with sufficient power.
Two kinds of motors are widely available.
- The stepper motor – use it to gain control
- The servo motors – use it to gain angular directions
Step 8: Designing your circuit
The next big step you should follow is to design the circuit. If you are too good in circuitry, of course, you can build your own. Or, there are various ways you can get some circuits at various web sites.
There are various ways in which you can design a circuit. You may use a bread board for practicing your circuit. Test your circuit as much as possible. You may find it interesting while designing your circuit.
Step 9: Programming the PIC
The main part of any robot making process is to program the PIC. Almost all PICs have a common basic architecture and electrical properties so the circuits described can usually be made to work with several other types of PIC.
The most direct way of programming a PIC is first to write the program in assembler, using a simple text editing program such as Notepad. This, or something similar, is provided as part of the Windows package. The top photo opposite shows a screen-shot of an assembler listing in Notepad. When the file is saved, Notepad creates a file in text file format (.txt). When asked for the file name to save it under, type the name with the extension ‘.asm’ (not ‘.txt’, and not without an extension). It is essential not to save the file with other formats, such a Rich Text Format. This inserts formatting control codes into the text. These codes will confuse the assembler program at the next stage.
A programmer board is usually supplied with the software that is used to turn the text file into machine code for downloading into the PIC. The software that comes with PICkit 2 includes the MPASM suite. The assembler program is called MPASMWIN, illustrated in the lower photo opposite.
When using the assembler software, the only thing you have to do is to type in the source file name, select the processor type, and click on ‘Assemble’. The other settings can usually be left as they are. With luck (or maybe skill), you are rewarded by a green display telling you that assembly has been successful. If you get a red display, check the error file and go back to Notepad. The error file has the same name as the assembler file, but with the ‘.err’ extension. Emulator software helps get things right more quickly. The MPLAB Integrated Development Environment, available from Microchip as part of the PICkit 2 package, is designed to do just this. It runs on your PC as if you have a PIC there and behaves just as a real PIC would behave. Its text editor does a lot of the formatting for you, including displaying the listing in several colours. Labels are in red, instruction codes are in blue bold, and so on. This makes the listing clearer to read and understand. When you think you have got it right the IDE can simulate the running of the program. The top left window in the screen-shot below shows the listing and an arrow at the left indicates the the line that is currently being processed. The lower left window displays the contents of the File registers, while at lower right we view the Special Function registers.
You can run the program and watch the values changing in the registers, exactly as they would in a real PIC. If you want to look more closely at a part of the program, you can go through it step-by-step. It is less confusing to write and test the program a little bit at a time. If something is wrong it is easier to spot it if only a short segment of the program is newly added.
When a part of a program or the whole program is working as you want it to, the IDE calls up programming software to transfer the assembled code to the memory of the real PIC on the programming board. Plug the PIC into its socket on the robot and the fun begins.
There is not enough space here to mention all the helpful features of the IDE. The thing to do is to download it and try it for yourself.
Step 10: Last But Not least
Last but not the least, connect the interface card with your computer and transfer the program to it. There are various ways by which you could do this. The best way is thru the parallel port. And after doing it all, take some break!!! And yes!!! You are done now. You may be confident in running the robot which you have made!!! You have become the GOD of your robot. Congratulations on your first robot. Enjoy !!!!
Feel free to post your comments below. This procedure does not not stop with making the robots alone. You have got a lot of opportunities to make money out of your robot all around the world. Don’t stop with building the robot alone, develop that to as much as you can.!!!
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