CONTENTS xmobile Robots xfischertechnik Mobile Robots xthe Kit xintroductory Example; Sliding Door xhelpful Tips
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Mobile Robots Today s high-tech world could not function without the aid of robots. For example, the use of so-called service robots in support of manufacturing processes is extremely widespread in many industries. The following figure shows just how numerous and varied the applications for mobile robots are. Shown here is a rolling robot developed by the Fraunhofer Institute for Production Technology and Automation in Stuttgart.
As a mobile information source, the robot guides visitors through the institute. The robot s touch screen can be used to call up a wide variety of information. This type of robot is also extremely well suited to other applications, such as the role of a museum guide. Robots are also used to perform physically hard or dangerous work, for example, in atomic energy plants or cleaning up contaminated areas. These types of applications require a high degree of mobility and movement capability. Here, mobility and independent action are the most important abilities. Robot movement is either remote controlled or pre-programmed into the robot with the aid of a computer. The development of computer-controlled walking robots represents a particular challenge. The purpose of this, is to teach the machines a variety of motions. In doing this, insect movements form the preferred model. The advantage of machines that can walk as opposed to those which employ wheels or rollers to achieve mobility, lies primarily in better mobility over difficult terrain and in overcoming obstacles.
The first serious attempts to develop walking machines took place in 1967 at a Tokyo university. Initially, human movement rather than that of insects or quadrupeds formed the model for the machine s walking actions. Ongoing development of these attempts finally led to the first, two- legged, walking machine in 1985. However, walking speeds were still very slow. The so-called Wabot-2 robot is
the star of the current crop of two-legged robots. It is outfitted with 50 degrees o freedom of motion and 78 microprocessors. With the aid of a CCD camera, the robot is able to read notes, play and organ, and even converse. Under the leadership of Prof. Y. Baudoin, an electro-pneumatic robot equipped with six legs and known as Achilles was developed and built by a team at the Royal Military Academy, Brussels. Equipped with a camera and optical proximity sensors on its upper surface and its six legs, this robot is designed to react to raised or sunken obstacles (objects or holes in its path).
Currently, the most famous mobile robot model can be found on Mars. The Rover Sojourner is a selfdirected robot being used to explore the Martian surface. It weighs approx. 11.5 kg, is about the size of a milk crate, and is propelled by six wheels. Solar cells are employed to provide the robot with the necessary energy to carry out its designated scientific and technical experiments. The power supply is supported by batteries for night work or for times of limited sunlight. The Rover Sojourner is equipped with cameras and sensors that allow it to find its own path across unknown terrain, and to avoid obstacles.
Future developments will increasingly concentrate on robots that control themselves. Application areas for these robots can be found wherever actions cannot be preprogrammed because of unpredictable changes in the environment. At this point, only humans can fulfill such tasks. Reasons for this include the lack of developed artificial intelligence, inadequate memory and processing capabilities, and the limited capabilities of current sensor systems. fischertechnik Mobile Robots Building machines and robots, writing control software for them on a PC, and setting the final product in motion appears, at first glance, to be a highly complex and technical task. However, fischertechnik turns it into a fascinating and creative hobby. MOBILE ROBOTS - the name is the concept because, for the first time, a construction kit has been supplied with an intelligent interface for home and
semi-professional applications. Using the Windows software, LLWIN (Lucky Logic for Windows), on a PC, programs can be created for mobile robot models. These programs are then loaded via the serial port to the new intelligent interface with its own microprocessor. The interface, built into the model, can then be disconnected from the PC and is capable of autonomously controlling the models. No longer is there an annoying cable running between the model and the PC to limit the model s freedom of motion. Models can now react to obstacles and changes in brightness just as real robots do. The Kit The kit contains a number of fischertechnik parts, motors, and sensors that can be used to build a total of eight different models. Three stationary starter models - a sliding door, pulse counter, and a stamp - provide an introduction to the uses of the components, the software, and the intelligent interface. This models are simple and easy to build and their application programs are uncomplicated and easily understood.
The five mobile robots, MR1 to MR5, are designed to perform different tasks: MR1, the base model with two motors and two position sensor switches, can travel forwards, backwards, to the left, and to the right along pre programmed.
MR2 uses its bumper to recognize obstacles and circumvents them.
MR3 recognizes ledges such as table edges. It can move around a table without falling off.
MR4 always follows a light source such as a flashlight directed at it.
MR5 is capable of moving along a black track laid out against a white background (e.g., insulation tape or magic marker).
The printed construction manual provides detailed information on building and wiring the models. The CD-ROM contains the LLWIN software, V2.1, with sample programs for each model, together with the LLWIN Handbooks and the intelligent interface. The models that can be built from the kit by no means exhaust the topic of mobile robots. Using other fischertechnik components, the models can be expanded, while the LLWIN software lets you create many of your own program concepts.
Introductory Example; Sliding Door First, we will build the sliding door introductory model, connect it to the PC, and then run it. This is designed to ease your way into the world of fischertechnik computing, and to clearly demonstrate the relationships between the fischertechnik model, the interface, and the software, as well as illustrate the difference between the active and passive modes. First, build the sliding door model and connect the cables and plugs to the interface as described. The model is also described in the printed construction manual.
Circuit Diagram
Now, using the connection cable, connect the interface to an open serial port on your PC (COM1 or COM2). If your PC is equipped with a 25-pin plug, the cable connector will not fit. In this case, you must purchase an adapter from your local computer retailer. After installing the LLWIN software on your PC, start it, and call up the Project window, then select Open from the pull-down menu and select the project door.mdl from the mobile directory. After selecting the Setup Interface function from the Options menu, you can specify the COM port you are using (COM1 or COM2) in the Port item.
Select Check Interface from the Options menu to test whether your computer is accessing the interface and whether the motor, lamp, and sensors have been properly connected. Use the left mouse button to start the motors turning to the left, and the right button to start them turning to the right.
If the motors do not operate or if the message No connection to the interface appears on the screen, check for the following possible error sources: x Is the power supply connected to the interface (red LED on)? You can use the Power on/off switch to interrupt the battery power supply to the interface. x Interface connection cable plugged in? x Have you specified the right interface in setup interface? x Is there an active mode program still running on the interface? To delete a program from the interface, briefly interrupt the power supply. When everything is running correctly, select the Start function from the Run menu. The program then runs in the so-called passive mode, in witch the interface is permanently connected to the PC.
The program first closes the sliding door. When the light barrier is broken, the door opens. The door remains open for a specified period of time, then automatically closes. The current door state is displayed on your terminal. To terminate the program, either select the Stop item from the Run menu, or press <F9>. Now restart the program, but select Download from the Run menu. This loads the program to the interface. Your screen no longer displays the current status. However, you can now disconnect the interface from your PC, and the program will continue running. To stop the program, press the switch on the right side of the interface. This switch is connected to E8 and activates the RESET software function block. Release the switch and the program starts from the beginning. The second Power on/off switch on the left of the interface interrupts the power supply if the interface is connected to a battery. This deletes the program from the interface and returns the interface to the passive mode. You must first delete an existing program before you can load a new or modified program, or restart a program in the passive mode.
Helpful Tips: x To switch from the active back to the passive mode or to load a program to the interface if one is already running on it, you must first briefly interrupt the power supply to the interface. This deletes any program on the interface and returns the interface to the passive mode, after which you can load a new program to the interface. x It is most practical to operate stationary models such as the sliding door in the passive mode. The connection cable to the PC does not interfere with the door s function, and your PC s terminal can be used as a display instrument. x On the other hand, mobile robots are naturally operated in the active mode, since real mobility can only be achieved by disconnecting the model from the PC. x The capacity of the interface microprocessor is limited. When programs with more than 80 function blocks are run in the active mode, rapid counting pulses (e.g., those coming from a pulse wheel) may not be counted correctly. You should therefore use the passive mode to process very large programs.
So much for an introduction into the fischertechnik world of computing. Now let s go! The construction manual contains instructions for the other starter models. Work your way through them before attempting the more complicated mobile ones. But remember, the mobile robots are waiting impatiently to finally explore the world outside the kit. Finally, we would be interested in hearing from you to find out how whether like the sliding door instructions on the CD-ROM, oder whether you prefer to use printed instructions. Please write us your comments and opinions! And now, have fun with you mobile robots.