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Background Information
The word "robot" was coined in 1921 when it first appeared in the play Rossum's Universal Robots by Karel Capek. It's a story about intelligent machines that run amuck when they are given emotions which lead them to conspire to destroy the human race.
Robots reached public notoriety in 1926 in the classic Sci-Fi film Metropolis in which a killer robot (disguised as a seductive woman named Maria) tried to destroy the world.
Humans and robots didn't get off to very good start together!
It wasn't until 1942, when Isaac Asimov began writing his series of robot stories, in which robots were dedicated to serving humankind, that our opinions of robots changed.
Although our earliest introduction to fictional robots may have evoked fear and suspicion, real robots have become an essential part of our everyday lives; contributing to our comfort, convenience, health and safety.
What is a Robot?
In its simplest form a robot is a machine; but the thing that most easily distinguishes a robot from an ordinary machine is that a robot seems "smart". Robots appear to have some degree of intelligence. We usually infer this machine-intelligence from the behaviour or action(s) of the robot. In other words, the most important thing that distinguishes a robot from other types of machines is that a true robot can exhibit intelligent autonomous behaviour.
A simple robot's ability to exhibit "intelligent behaviour" may be cued by one or more of the following:
- changes in time: (the robot must perform an operation at a specific time or after a prescribed elapsed time);
- changes in location: (the robot must perform an operation at a given place);
- changes in environment: (the robot must perform an operation at a pre-determined temperature, pressure, radiation level etc.).
Notice that in all cases the robot must be programmed to recognize the conditions which will cause it to respond with "intelligent behaviour".
A really "smart" robot is one that can modify its own program (and therefore its behaviour) and adapt to changing conditions.
Robots vs Remote Control
One must be careful not to confuse robots with remotely controlled machines. For example, radio controlled model airplanes are not really robots since they are always (hopefully) under the direct control of a human observer; whereas, a simple pop-up toaster is a robotic device because it can be programmed to exhibit intelligent autonomous behaviour (it "pops" up perfectly browned toast without human intervention.)
The amazing Canadarm and Canadarm2 are machines which are both robotic and remotely controlled.
Simple robots perform actions based on a set of one or more instructions which are input, stored, and followed according to a timed sequence.
A complex robot is programmed to assess external conditions and can modify the event sequence according to whatever external conditions it finds.
The Three Primary Categories of Robots
Directly controlled robotic devices.
These are the most common type of robots, many of which we come in contact with in our everyday lives. These directly controlled robotic devices are also known as programmable devices since their apparent intelligence is acquired from specific instructions that we program into them.
Examples of directly controlled robotic devices include microwave ovens, VCRs, and desktop computers.
Semi-autonomous robotic devices.
These are directly or remotely controlled devices that can make simple decisions. For example, semi-autonomous robotic devices can detect when a problem occurs and then take appropriate action to remedy the problem. Even "smarter" semi-autonomous robots can anticipate that a problem is likely to occur (based on its detection and evaluation of current conditions) and then take appropriate action to prevent the problem.
The sophisticated Canadarm2 is an excellent example of this type of robot. It is sufficiently intelligent in that it is capable of avoiding potentially catastrophic actions such as a collision with itself. This sense of "robot-self-protection" allows it to protect itself against accidental operator error.
Fully autonomous robotic devices (true robots).
These robots are capable of assessing all external conditions and formulating appropriate action(s). So far, no robot has been created (except in science fiction) which is fully autonomous in all activities; however, some robots have been designed to exhibit autonomous behaviour in selected tasks.
Build a Directly Controlled Robotic Camera
Robotically explore your neighbourhood from the sky
Note to teachers
This design is extremely easy to build. It uses inexpensive and readily available materials.
This activity can be used as a focal point for much of the mechanics (kinematics and dynamics) in secondary school physics at both the introductory and advanced levels.
For teachers who wish to integrate this activity into a semester-long project in mechanics, relevant topics have been suggested with each stage of the construction process.
It is strongly recommended that students keep a construction journal. In their journal they should write detailed notes recording all their observations, results of any experiments, and any conclusion they may have drawn from building each component of their robot, as well as all other data related to their project.
The task of building a robotically controlled, remote sensing device, attached to a moving (and a sometimes unstable) platform shares a great deal in common with the design of similar devices for spaceflight applications. It will provide your class with plenty of opportunity for experimentation and design modifications. The primary objective of this activity is to build and operate a robotic camera, and in the process of building this device, explore the physics of its design.
The robotic camera platform is suspended from a home-made (or store-bought) kite. It is able to take aerial photographs at a time programmed into its "nanobrain" prior to launch.
The altitude and direction of the aerial photograph depends upon the length of the kite string and the orientation of the camera.
The photograph above shows the robotic camera in flight.
There are several types of such cameras on the market. All of them work equally well for this project.
Évitez les appareils jetables légèrement Try to avoid the slightly more expensive disposable cameras which have a built-in flash. The distance from the camera to the ground is too far to make the flash useful under low-light conditions. The flash only serves to make the camera heavier.
One of the great features of small disposable cameras is their truly remarkable low mass.
Our camera had a mass of only 67 grams.
The foam insulation is pink (although other colours are available) and has a very hard smooth surface. The interior foam has a relatively small cell structure, which makes this product very strong and very light.
Do not use white styrofoam. White styrofoam has an interior cell structure that is too coarse (big) to give the material much strength. It breaks much too easily.
Using a set of standard masses you can test the lifting capacity of your kite. Experience has shown that kites lift payloads best when the payload is attached about 2 to 3 metres from the kite's attachment point to the kite string.
Kite designs vary greatly. While some designs have a lot of lift, others have better flying characteristics and greater stability.
Explore your kite's lifting capacity as a function of wind speed.
Explore other kite designs.
Of course a robot wouldn't be a robot if it did not have some level of intelligence. Our robot is not very smart, it only "knows" that after a certain amount of time has elapsed that it is supposed to trip the shutter of the camera.
Our robot's brain (we'll call it a "nanobrain" since it's not very smart) is a small mechanical timer extracted from a cheap kitchen timer. It can be set for time delays up to 60 minutes.
Our timers (two of them shown in the photo) cost exactly two dollars each (plus tax) from the kitchenware department of a discount store.
You will need to remove the fancy casing from the timer. Simply pull off the dial and remove the small screws from the back. The timer will simply fall out.
A set of small hobby screwdrivers is required because the screws that hold the timer in the case are quite small.
The nanobrain (timer) needs to be set up so that it can release the camera's shutter at the appropriate time. This is accomplished by building a shutter-release mechanism as illustrated.
Details of how to install it are shown later, but the basic concept is illustrated here.
An old plastic credit card makes a very good shutter release plate. It is light, strong, and most importantly, it has a low coefficient of friction (it is very slippery).
Causes of friction;
Coefficients of static and kinetic friction;
Methods of reducing friction.
A pair of needle-nose pliers is helpful.
Examine the diagram carefully. Note the alignment of the various components.
Elastic bands are used extensively in this project. Have lots of them available.
The key idea is to use the shutter release plate to prevent the shutter post from pushing down on the shutter button of the camera. The diagram to the left illustrates this.
As the timer un-winds (in a counter-clockwise direction) the wire arm gradually extracts the shutter release plate from underneath the shutter post, which will then push down on the camera's shutter button.
Test your design carefully to ensure that it functions as you predict. Make whatever adjustments are needed.
In understanding the function and operation of the timer, and how it extracts the shutter release, consider the following topics:
Torque;
Measuring torque;
Increasing the force applied to the shutter release plate;
Gears;
Levers.
The payload package must be designed so that it is both aerodynamically stable and extremely light. (See below).
In order to minimize any interference with the flight characteristic of the kite, the payload should be flown at least two metres from the kite. Testing your kite with a simulated payload prior to an actual robotic flight is both helpful and instructive.
Swivel hooks (or fishing leaders) are required to prevent unwanted kinks and knots from forming in the kite and payload strings.
Most important
Remember: Never fly a kite where there is the slightest chance of it coming into contact with overhead wires or when there is any risk of lightning.
Aerodynamic Stability
A large cardboard or bristol-board fin (called a vertical stabilizer) is attached to the opposite end of the doweling so that it acts as a weather-vane, pointing the camera into to wind, as illustrated.
In order to minimize any interference with the flight characteristic of the kite, the payload should be flown at least two metres from the kite. Testing your kite with a simulated payload prior to an actual robotic flight is both helpful and instructive.
To fully appreciate the design, the following topics should be investigated:
The moment of inertia for a long uniform solid rod;
Centre of pressure (as related to air flow) over and around an airplane or fin;
Centre of mass;
The relationship between centre of mass and centre of pressure as related to aerodynamic stability.
Be careful about causing changes in the "centre of pressure" when the robotic camera is aligned to take photos at right angles to the wind direction. Be certain that the fin is big enough!
The centre of aerodynamic pressure (on the side of the payload) must always be behind the centre of balance.
If you fly your kite in extremely turbulent winds some additional stability can be produced by adding a horizontal stabilizer, but this will be at the expense of additional payload mass. Our payload did not require it.
Construction and Flying Details
» Step by Step Instructions
for the Canadian Space Agency.
