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RobotShop Grand Tutorial: How to Make a Robot - Lesson 2

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Following the first lesson, you now have a basic understanding of what a robot is and what current robots normally do.

Now, it is time to decide on the type if robot you are going to build. A custom robot design often starts with a “vision” of what the robot will look like and what it will do. The types of robots possible are unlimited, though the more popular are:

  • Land wheeled, tracked, and legged robots
  • Aerial planes, helicopters, and blimp
  • Aquatic boats, submarines, and swimming robots
  • Misc. and mixed robots
  • Stationary robot arms, and  manipulators

This lesson is intended to help you decide what type of robot to build to best suite your mission. Since you have brainstormed on what tasks or functions you want it to accomplish (after lesson 1),  you can now choose the type of robot that will best suite your needs. Below, you will find a description of all the major robot types.

Land

Land-based robots, especially the wheeled ones,  are the most popular mobile robots among beginners as they usually require the least investment while providing significant exposure to robotics. On the other hand, the most complex type of robots is the humanoid (akin to a human), as it requires many degrees of freedom and synchronizing the motion of many motors, and uses many sensors.

Wheeled Robots

Mobile Wheeled Robots

Wheels are by far the most popular method of providing mobility to a robot and are used to propel many different sized robots and robotic platforms. Wheels can be just about any size, from a few centimetres  up to 30 cm and more . Tabletop robots tend to have the smallest wheels, usually less than 5 cm in diameter. Robots can have just about any number of wheels, although 3 and 4 are the most common. Normally a three-wheeled robot uses two wheels and a caster at one end. More complex two wheeled robots may use gyroscopic stabilization. It is rare that a wheeled robot use anything but skid steering (like that of a tank). Rack and pinion steering such as that found on a car requires too many parts and its complexity and cost outweigh most of its advantages.

Four and six wheeled robots have the advantage of using multiple drive motors (one connected to each wheel) which reduces slip. Also, omni-directional wheels or mecanum wheels, used properly, can give the robot significant mobility advantages. A common misconception about building a wheeled robot is that large, low-cost DC motors can propel a medium sized robot. As we will see later in this series, there is a lot more involved than just a motor.

Advantages

  • Usually low-cost compared to other methods
  • Simple design and construction
  • Abundance of choice
  • Six wheels or more rival a track system
  • Excellent choice for beginners

Disadvantages

  • May lose traction (slip)
  • Small contact area (only a small rectangle or line underneath each wheel is in contact with the ground)

Tracked Robots

Mobile Tracked Robot

Tracks (or treads) are what tanks use. Although tracks do not provide added “force” (torque), they do reduce slip and more evenly distribute the weight of the robot, making them useful for loose surfaces such as sand and gravel. Also, a track system with some flexibility can better conform to a bumpy surface. Finally, most people tend to agree that tank tracks add an “aggressive” look to the robot as well.

Advantages

  • Constant contact with the ground prevents slipping that might occur with wheels
  • Evenly distributed weight helps your robot tackle a variety of surfaces
  • Can be used to significantly increase a robot’s ground clearance without incorporating a larger drive wheel

Disadvantages

  • When turning, there is a sideways force that acts on the ground; this can causeTank Tracks Damage damage to the surface the robot is being used on, and cause the tracks to wear
  • Not many different tracks are available (robot is usually constructed around the tracks)
  • Drive sprocket might significantly limit the number of motors that can be used.
  • Increased mechanical complexity (idler placement and number, # of links) and connections

Legs

Mobile Legged Robot

An increasing number of robots use legs for mobility. Legs are often preferred for robots that must navigate on very uneven terrain. Most amateur robots are designed with six legs, which allow the robot to be statically balanced (balanced at all times on 3 legs); robots with fewer legs are harder to balance. The latter require “dynamic stability”, meaning that if the robot stops moving mid-stride, it might fall over. Researchers have experimented with monopod (one legged “hopping”) designs, though bipeds (two legs)quadrupeds (four legs), andhexapods (six legs) are the  most popular.

Advantages

  • Closer to organic or natural motion
  • Can potentially overcome large obstacles and navigate very rough terrain

Disadvantages

  • Increased mechanical, electronic and coding complexity (not the easiest way to get into robotics).
  • Lower battery size despite increased power demands
  • Higher cost to build

Air

Mobile Aerial Robot

A AUAV (Autonomous Unmanned Aerial Vehicle) is very appealing and is entirely within the capability of many robot enthusiasts. However, the advantages of building an autonomous unmanned aerial vehicles, especially if you are a beginner, have yet to outweigh the risks.  When considering an aerial vehicle, most hobbyists still use existing commercial remote controlled aircraft. On the professional side, aircraft such as the US military Predator were initially semi-autonomous though in recent years Predator aircraft have flown missions autonomously.

Advantages

  • Remote controlled aircraft have been in existence for decades (so there is a large community, at least for the mechanics)
  • Excellent for surveillance

Disadvantages

  • The entire investment can be lost in one crash.
  • Limited robotic community to provide help for autonomous control

Water

Mobile Underwater Robot

An increasing number of hobbyists, institutions and companies are developing unmanned underwater vehicles. There are many obstacles yet to overcome to make underwater robots attractive to the wider robotic community though in recent years, several companies have commercialized pool cleaning “robots”. Underwater vehicles can use ballast (compressed air and flooded compartments), thrusters, tail and fins or even wings to submerge. Other aquatic robots such as pool cleaners are useful commercial products.

Advantages

  • Most of our planet is water, so there is a lot to explore and discover
  • Design is almost guaranteed to be unique
  • Can be used and/or tested in a pool

Disadvantages

  • Robot can be lost many ways (sinking, leaking, entangled…)
  • Most electronic parts do not like water (also consider water falling on electronics when accessing the robot after a dive)
  • Surpassing depths of 10m or more can require significant research and investment
  • Very limited robotic community to provide help
  • Limited wireless communication options

Miscellaneous and hybrid combinations

Mobile Miscellaneous Robots

Your idea for a robot may not fall nicely into any of the above categories or may be comprised of several different functional sections. Note again that this guide is intended for mobile robots as opposed to stationary or permanently fixed designs (other than robotic arms and grippers). It is wise to consider when building a hybrid design, to use a modular design (each functional part can be taken off and tested separately). Miscellaneous designs can include hovercraft, snake-like designs, turrets and more.

Advantages

  • Designed and built to meet specific needs
  • Multi-tasking and can be comprised of modules
  • Can lead to increased functionality and versatility

Disadvantages

  • Possible Increased complexity and cost
  • Often times, parts must be custom designed and built

Arms & Grippers

Not-so-mobile Robot Arms

Although these do not fall under the category of mobile robotics, the field of robotics essentially started with arms and end-effectors (devices that attach to the end of an arm such as grippers, electromagnets etc). Arms and grippers are the best way for a robot to interact with the environment it is exploring. Simple robot arms can have just one motion, while more complex arms can have a dozen or more unique degrees of freedom.

Advantages

  • Very simple to very complex design possibilities
  • Easy to make a 3 or 4 degree of freedom robot arm (two joints and turning base)

Disadvantages

  • Stationary unless mounted on a mobile platform
  • Cost to build is proportional to lifting capability

Practical Example

In our case, we have opted for building a robot that will provide the maximum exposure to robotics. A programmable tracked platform that can accommodate a variety of sensors and gripper sees ideal in this case, specially since we consider tank tracks  are far cooler than wheels.

In order to keep the costs down, we opted to build a small desktop robot that will be able to roam indoors and on tabletops. We also have taken into consideration the fact that there are not many tracks available, and to keep things simple, we’ll only consider a single drive sprocket and single idler sprocket system, this should not be a problem since the robot will be very light weight.

The preliminary CAD below summarized the features describes so far.

Preliminary rover CAD with human hand

Next, we will be choosing the right actuators (e.g. motors) for your robot.

RobotShop - Robotics at your serviceFor further information on learning how to make a robot, please visit the RobotShop Learning Center. Visit the RobotShop Community Forum in order to seek assistance in building robots, showcase your projects or simply hang-out with other fellow roboticists.

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52 Responses to “How to Make a Robot – Lesson 2: Choosing a Robotic Platform”

  1. javeed

    hiii frns this is a gud place for the beginners who are interested in robotics….

  2. Martin White

    Could you show me how to do this in a live video stream on a certain time? I’d really like to see it and ask some questions.

    I myself usually use ustream or http://www.tvmad.com maybe they’ll help ya.

    If yould be willing to do it then let me know, I’d be 100% there to watch it.

    Cheers

  3. Kelly Armstrong

    When are the other lessons published? I see that they stopped at Lesson 3 and the rest are grayed out. Any info?

  4. Carlos

    Hi Everybody.

    Thank you for the great feedback, we really appreciate it. In order to get help with making robots, we suggest you visit our forum: RobotShop Community Forum

    There you will be able to find help from the RobotShop technical team and from other roboticists.

  5. Devendra

    i want to make a robote but dont have any idea about robote what should i do .
    plz tell to me as soon as possible

  6. bill

    you should tell us more and how to make a robotic arm, anyway that was cool

  7. raza

    i m new in robotic…………….Is there anyone who will help me???????????????

  8. atul kumar

    i m new in robotic…………….Is there anyone who will help me???????????????

  9. NITIN RAWAT

    i m beiginer for learning the robotics skill. i don’t know how to make successful robot. please help me to make the Robot for wars and game.

  10. Arsenal

    I am gaining lots of information and this a good platform for beginers…..Thanks a lot

  11. kartikey tiwari

    i like this website verymuch this is good job for every person as who want to know about robot& learn to make the robot.
    THANKS

  12. Nick M'sewa

    Slt ! J’aimerai bien apprendre comment interagir avec un robot par voie vocale…
    Merci de m’aider…
    Hi ! I wants learn about voice commands in robotic…
    Books, sites, and more…
    Plz help me…
    Thanks…

  13. kiti

    hy can i know how to make a very simple robot without progammed and work on wiring it with remote

  14. wallance

    can u show me more about the arm and gripper?
    tat is more interesting 4 me..tq^^

  15. susin

    very nice information to learn merits and demerits adout robots in all source,,,,

  16. alok das

    sir , i want to know the principle involved in the construction of bi-ped legs and its control . can u please send answer to my question in my mail

  17. hashim

    I need to build a robot but I don’t have idea on that please can u send me all necessary material to guide me in my mail

  18. tejaswi

    i need to build basic remote controlled robot. can you plz send the necessary details.

  19. tejaswi

    Can u plz tell me a good site name , where i can get information on how to build a remote controlled robot.

  20. cbenson

    You don’t need much to build an R/C “robot”; a remote control, an R/C motor controller, two motors, two wheels, hubs and a battery (and of course a frame). Contact via the Forum and we can give you more details.

  21. cbenson

    It does not take much. Contact us via the RobotShop Forum and give us some details about what you want to do, and we would be happy to help.

  22. uriti rajesh

    this is a nice one to make a robot without knowing basics also we can create robots

  23. claude

    is so great that make me very excited !! wow i appreciate in u courage !!!!!!!! keep it up !!

  24. aditya

    please suggest me 4 making a robot , Every step with a suitable example…????
    i need it….:(
    plz

  25. cbenson

    That’s what these lessons are for. You might also consider a robotic kit which provides step by step assembly instructions.

  26. varun

    i hope wht abt that in my life jst make the one robot only any one dnt help to me y bcz i meeted persons r not perfect so plz send me u r suggetion to my mail if any thk u…….varun

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