Electromagnetic shoot

The science fair device described in this paper shoots a miniature soccer ball using a solenoid and a two-piece rod made of iron and nylon. The nylon part of the rod is introduced inside the solenoid and a ball is placed at its extremity. When an electrical current passes through the solenoid, the iron part of the rod is pushed into its center, causing the shooting of the ball. This mechanism, originally developed for Minho Team soccer robots, has been successfully used for several years. The science fair version includes a slewing iron case and overheat protections

Electromagnetic shoot

The science fair device described in this paper shoots a miniature soccer ball using a solenoid and a two-piece rod made of iron and nylon. The nylon part of the rod is introduced inside the solenoid and a ball is placed at its extremity. When an electrical current passes through the solenoid, the iron part of the rod is pushed into its center, causing the shooting of the ball. This mechanism, originally developed for Minho Team soccer robots, has been successfully used for several years. The science fair version includes a slewing iron case and overheat protections.Robótica 2006 – Festival Nacional de Robótica (National Robotics Festival), Guimarães, Portugal, April 28 – May 1, 200

Computer-controlled model railroad

Model railroads are good test beds for several scientific experiments on Electromagnetism, Electronics, Automation, Control and Computer Science. Moreover, they are eye-catching structures very well suited for science-fair events. This paper describes a 2m x 1m model railroad layout and a user-friendly program, built with LabVIEW graphical language. The program is able to control train direction and speed, and also allows the control of thirteen switch-points, lights and a mountain funicular, all included in the layout. The interface between personal computer and railroad circuits is done with a standard multi-purpose data-acquisition board for the PCI bus

Alternating current and direct current generator

Spinning a wire loop within a uniform magnetic field in a convenient fashion induces a voltage between the loop terminals. This effect can be used to build an electric power generator, such as the one described in this paper. A coil attached to a shaft spins within the magnetic field of a "U" shaped magnet. Three conveniently designed conductive disks allow the electrical load of the generator to be fed either with alternating current or direct current

Handmade series direct-current motor

Using common materials, it is possible to build a variety of very simple - and yet functioning - electric devices. These devices can be used to verify Electromagnetism fundamentals. Electric currents within magnetic fields originate forces and that is the basic principle of operation of electric motors. This paper describes a universal series motor made with iron bars, insulated copper wire, two small brass plates, insulating tape, six screws and a couple of hoops. The motor is fed with a personal computer 12V DC switched power supply. Rotor speed can achieve several rotations per second

Microcontroller-driven hydrogen car

This paper presents a hydrogen-powered car with 8 minutes autonomy. The hydrogen is produced by electrolysis, which requires an external power supply. The gas is retained on an isolated compartment in the car. Then, it goes to the fuel cell, which produces the energy for the car motor. The car follows a white line on a black track using five infrared sensors that detect white and black colors. A servomotor controls its direction. Guidelines to the servomotor are given by a system based on an 8051 microcontroller, according to the information it receives from the infrared sensors

Induction coil gun

This paper describes a device capable of throwing metal rings at a range of a few meters. Part of an iron pipe is inserted on a coil. A conducting non-ferromagnetic ring is inserted in the pipe through its other extremity. An alternating current flowing through the coil creates an alternating magnetic field, which magnetizes the iron pipe. So, an alternating magnetic field is created around the pipe and induces a circumferential current flowing in the ring. This current is repelled by the magnetic field, forcing the ring to jump out of the pipe

Position and orientation errors in mobile robot absolute self-localization using an improved version of the generalized geometric triangulation algorithm

Triangulation with active beacons is widely used in the absolute localization of mobile robots. The original Generalized Geometric Triangulation algorithm suffers only from the restrictions that are common to all algorithms that perform self-localization through triangulation. But it is unable to compute position and orientation when the robot is over the segment of the line that goes by beacons 1 and 2 whose origin is beacon 1 and does not contain beacon 2. An improved version of the algorithm allows self-localization even when the robot is over that line segment. Simulations results suggest that a robot is able to localize itself, with small position and orientation errors, over a wide region of the plane, if measurement uncertainty is small enough

Electric power generating bicycle

It is manifest the growing interest in both personal health and environmental issues. The device described on this paper contemplates both aspects: generating environment-friendly electric power while keeping fit. A car alternator excited through a 12V battery is coupled to a mountain bicycle, and this arrangement enables the lighting of six halogen lamps, if a cyclist pedals fast enough. Such a machine gives rise to the thought of a self-powered gymnasium. Considerable physical effort is required in order to make the lamps glow, which is pedagogical since it shows clearly that spending energy is much easier than generating it

Generalized geometric triangulation algorithm for mobile robot absolute self-localization

Triangulation with active beacons is widely used in the absolute localization of mobile robots. The Geometric Triangulation algorithm allows the self- localization of a robot on a plane. However, the three beacons it uses must be “properly ordered” and the algorithm works consistently only when the robot is within the triangle formed by these beacons. This paper presents an improved version of the algorithm, which does not require beacon ordering and works over the whole navigation plane except for a few well-determined lines where localization is not possible