May 13, 2009
How to Build a Robot
If you’ve ever wanted to attempt to build one of those amazing robots you’ve seen on television, it’s time to learn. You don’t need an expensive physics or engineering degree to have a robotics hobby. With enough interest and skill, you can practice robotics as a hobbyist. Although understanding of subjects such as electronics, programming, and engineering can make learning the hobby of robotics easier, it is not necessary. If you have motivation, you can slowly learn the skills to become a robotics hobbyist.
As with any hobby, you need to know where to start. Probably the best thing to have as a beginner is $200-$400 to begin. As you build your knowledge, you won’t need to buy expensive kits but rather purchase the parts to build the robot, ultimately making the cost cheaper. As a beginner, however, the best way to begin your new hobby is through the purchase of a robot kit. If you have a basic understanding of computer programming, you are one step closer to a better understanding. For instance, the beginner robot kit from Parallax requires JAVA and PBASIC programming.
Now, if the cost of a kit is too much for your budget, you can attempt to build your first robot from simple, affordable household items found around your house or that you can purchase at your local hardware store. Keeping in mind that your first robot should be simple, you want to create your first robot to have the most simplistic design. The goal for your first robot is to learn the basics with the fancy, exotic extras kept for when you become an intermediate and advanced hobbyist. The simplest parts needed for a homemade robot are wheels, a source for power (battery), a motor, microcontrollers, and sensors.
Wheels are the easiest concept to grasp. Wheels are, obviously, the way your robot will gain movement. The programming for the movement comes later, but you should take into consideration the width and diameter for each wheel. In general, as the wheel diameter of your robot increases the speed will increase, but the torque will decrease. This is great for robots moving in a straight line at an increasing speed. Perhaps this is your goal. If the wheel is too thick or bulky, however, it can be more difficult for your programming and maneuvering during its first run.
Now it’s time to decide on the motor of your robot. The calculation needs of a robot motor can involve many factors for a highly advanced robot. Factors such as weight, gearing ratios, desired terrain, desired velocity and acceleration, voltage, power consumption are just a few of the basic considerations when designing a robot. The best advice for a beginner’s robot is to keep the parts and overall weight of your robot to a minimum. In other words, create your robot with the lightest parts possible. You don’t want to have the whole robot built and the motor is unable to power it to move.
Although you could plug your robot into the wall for power, you want it to be able to move freely. Using a battery to power your robot is the best option. More advanced robots may be able to use solar energy, but for a beginner a simple battery function robot is best. There are two types of beginner batteries available. NiMH (Nickel Metal Hydride) batteries are more expensive, but they are the best quality batteries available.
They take a few hours to charge, but they are easily reusable without the degradation issues of other batteries. NiCad (Nickel Cadmium) is the same style batteries as the older cell phones used. While they are cheaper and most affordable for your first robot, they slowly degrade over time. The more you charge the battery, the less amount of time it will have charge. It should also be noted that the first charge of a NiCad battery should have a full charge, just like old cell phones required you to fully charge its batter for first time use.
Microcontrollers may be the most difficult for beginners if you do not have some kind of understanding of basic programming. The range in price for a microcontroller is quite large. Prices range from $80 - $600 dollars. The popular types of controllers include PIC, Atmel/AVR, ARM, and BASIC Stamp. BASIC stamp provides the easiest for a beginner for a seasoned programmer or a beginner who will also need to become educated in programming. Depending on what kind of microcontroller you choose will decide what type of programmer you need to purchase. The programmer uploads the code to the chip, so it is a necessity when choosing a microcontroller.
For beginners to programming, microcontrollers provide sample programs for you to use. For seasoned programmers, you want to brush up on your BASIC and JAVA language. When choosing the right microcontroller as a beginner, choose the one with the least amount of learning curve. Right now, your goal is to control the robot with the least amount of learning possible. As you learn more, you can expand your programming language and knowledge into more complex microcontrollers.
Finally, sensors are needed for your robot. You can take the easy route and simply purchase an RC remote. This will remote control your robot, however, the important part of fully understanding robotics as a hobbyist is to understand autonomous movement. Sensors give your robot a sense of organic, learning movement.
There are several types of sensors. Photosensors are probably the most simple of sensors for a beginner robotics hobbyist. A photosensor works in the same common sense your brain works, and they are usually under a dollar to purchase. A photosensor detects different levels of light. When properly placed at each side of the robot, it can determine precise movement. If darker shadows start to show on the right side of the robot, it should be programmed to move left.
The same logic would apply if shadows appear on the left side of the robot in that it should move right. If light is evenly distributed on both sides of the robot, then it should know to continue moving straight. Additionally, if shadows start to appear below the sensors, then your robot should autonomously know that there is an object blocking straight movement.
If you really want to plan ahead for your robot design, you can use a design software program like CAD to layout the plans for your robot construction. These software programs are expensive, but they can give you a look and feel for what your robot will look like after final construction. It may also help you find any mistakes or corrections needed instead of figuring it out after or during construction. While designing a plan through CAD, you can also calculate algorithms and decide on dynamics of parts needed for a particular style of robot.
You will need to decide what kind of material to use for your robot chassis. Since you are buying your first motor with the idea that construction will be light weight, you want to find the cheapest and lightest materials possible. If you build your robot too heavy, your motor might not have enough torque to push the robot from no movement into acceleration. Aluminum is an easy to find material that is light weight and easy to work with. An even better, more flexible material is Styrofoam. This material can often be found in your house. It is not only light weight, but it is easily formed to fit the look and feel for your new robot.
You will also need screws, tape, and adhesives to put fine details and parts together. If you decide to invest and create LEDs on your robotic, you will need a soldering equipment. Soldering tools will become useful for future robotics development, so if your budget permits it is not a bad idea to invest in one.
Screws are a small item needed, but there are several sizes and shapes. Remember when choosing a screw type to consider the screwdrivers and possible wrenches needed to add and remove them. Again, the simpler you make your design, the simpler it will be to understand it for future reference. Using few screw types will make it easier for you to take apart and reconstruct your robot.
This is especially handy if, after construction, you need to take it apart for any reason. Since it is your first robot, it is likely that you may need to take it apart after construction due to a technical issue. If your robot doesn’t work on your first try, then expect to take it apart to figure out where you went wrong.
You may want to get really fancy and exotic for your robot’s look. Robotics has become more popular since television has made it a sport. Just remember that you are a beginner, and as with any beginner project you should keep it as simple as possible. By trying to design a more advanced robot, you might find yourself frustrated. Frustrations lead to loss of motivation and possibly quitting the hobby, so try to keep your robot as simple as possible and work yourself up to a more advanced design.
Robotics is a fun and interesting hobby for those who are technically inclined. If you are interested in robotics as a hobby, try it out and see how you do. While it isn’t a simple hobby, it can give you plenty of satisfaction after you see your first creation move and animate for its first time.
Written by: John
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