Protective strip for snowplough

An elastic strip made of Baytec P on the front of a snow-clearing machine has enormous advantages. It is easy to install and, because it is so hard-wearing, it lasts for several winters.
Apart from this, it remains highly flexible even at sub-zero temperatures, preventing damage to the roads. The outstanding resilience of Baytec P means that the protective strip will spring back from any obstacle it hits and thus prevent damage to the vehicle. With all these advantages, the snowplough can work fast without fear of being damaged

Device for light therapy

A light therapy device that specifically activates the self-healing forces, relieves the organism and triggers regenerative processes has been developed by Bioptron AG in Mönchaltorf, Switzerland. The Bioptron 2 model works by encouraging cell activation, known as biostimulation of the cell. The housing of this device is manufactured by emaform AG, which is based in the Swiss town of Gontenschwil. The company uses the Baydur® 60 polyurethane integral skin foam system, developed by Bayer MaterialScience AG primarily for the production of technical housings.

On the look-out for a lightweight, tough and rigid material which would reproduce the complex design of the light therapy device perfectly, the choice fell on Baydur® 60. Because with its excellent flow properties, this polyurethane system has proved its suitability even for the production of large moldings with complex geometries. Thanks to its mold reproduction accuracy, finely detailed textures can also be rendered.

Another argument for integral skin foam system from BaySystems is that it forms a solid outer layer which, together with a two-pack polyurethane coating, produces a highly-resistant, easy-care surface.

Baydur® 60 also delivers the goods as far as economics are concerned. The parts can be made with inexpensive aluminum molds because the internal pressure generated in the mold is particularly low. Apart from this, the integral skin foam can easily be combined with other materials, which means, for example, that thread inserts can be pre- positioned in the mold and molded in place, considerably simplifying subsequent fabrication.

Helios movie projector

A cabinet can be far more than a handy, light and robust case. This has been proved by the Helios video projector and its sophisticated exterior made of Baydur® polyurethanes from BaySystems®. Available in a variety of colors, it is perfectly at home in its environment, whether at conferences or presentations.

The Helios digital video projector from the Italian company Vidikron Industries S.p.A. has a special visual appeal in more than one sense. The highly sophisticated electronics packed inside the set are protected by a cabinet manufactured by 2a.effe of Lissone, Italy, using polyurethanes Baydur® 60 and Baydur® 110 from BaySystems®. In addition to offering a perfect combination of design and functionality, these two materials also provide a number of structural benefits, including an excellent surface finish that is ideal for high-grade coatings and gives the projector a distinctively elegant appearance

H-Bridge for Robots with High Current DC Motors

DC Motors which need high current and high voltage usually give high velocity and high torque. For small robots like line follower robot or fire fighting robot, I think IC motor driver L298 (up to 2A total current) is better choice. While for large and heavy robot, you need high current DC motors also H-Bridge suit to your DC motor.

This article sould be useful for you to build high current H-Bridge. H-Bridge schematics provided…

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The H-Bridge is the link between digital circuitry and mechanical action. The computer sends out binary commands, and high powered actuators do stuff. Most often H-bridges are used to control rotational direction of DC motors. And unless you buy a potentially expensive motor-driver, you need an H-bridge to control any robot with a motor.

This is a quickly sketched H-Bridge circuit with supporting circuitry.
H-Bridge

First lets talk about what a transistor is. These nifty chips revolutionized the electronics industry and you would be hardpressed to find something electronic that does not have at least a few thousand of these in them. So what do they do? They can control a flow of electrons by applying a voltage to them. The plumbing equivalent would be a water valve. By rotating the valve, a very large flow of water can easily be controlled.

MOSFET, Transistor
There are several types of transistors, such as the PNP and NPN, but for sake of making your life easy I will only talk about a MOSFET (Metal-Oxide Semiconductor Field Effect Transistor). These neat things have only been around for a decade or two, but are way better than the more traditional transistor. First they are more efficient. They are easier to calculate mathwise. Plus they usually have built in protection diodes so you don’t need to add them in later. They even have PWM (explained later) optimized MOSFET’s.

So to operate a MOSFET, you apply a voltage to the gate (from your microcontroller), and suddenly a current of electrons passes through the other two pins. Connect a motor (M) in line with one of the pins and your robot is set to go. In the above schematic you will notice the letters A and B. These are your two control lines which you apply this logic voltage to. Since you have two pins, and only a binary control, there are four possible things that can happen.

A=0 B=0 : Nothing happens, the motor is turned off
A=1 B=0 : Motor rotates clockwise
A=0 B=1 : Motor rotates counterclockwise
A=1 B=1 : Your circuit explodes into pretty sparks

Here is a ghetto visual graphic of the H-bridge logic chart:
H-Bridge A

H-Bridge B

So now lets talk about how to operate the MOSFET’s. Basically all you need to do is attach the gate to your digital output of your controller. When the digital output is turned on, 5V will be applied to the gate, turning the MOSFET on. However it is better to amplify that 5V to a value higher and I will explain why. The gate voltage controls the MOSFET internal resistance. Zero voltage makes the resistance too high for it to work. A very high voltage has a very low resistance. Resistance leads to loss of energy thermally. This means your MOSFET will heat up and possibly burn out. Take a look at the MOSFET picture above and you will notice my finger print in it. That is what happens when you touch a hot MOSFET - pain! So although you do not need to amplify the gate voltage, it is best to do so. You should also put a heat sink on it.

Square Wave for Pulse Width Modulation PWM
Ok so what if you want speed control, and not just an on/off switch? PWM! Pulse width modulation. PWM is when you send a square wave at a certain frequency to control the MOSFET as shown above. Basically you are telling your controller to turn on and off the motor at very high rates. So through inductance the motor is neither fully on or fully off, but somewhere in between. Such as at a slower speed. Also a note that motor torque, under PWM, remains the same whether fully on or only a percentage on. However, varying voltage for speed control reduces torque. So with PWM you have maximum torque yet slower speeds! You will have to experiment with wave length for both on and off periods, as well as frequency, to optimize your speed control. But a guess usually works.

Make sure the MOSFET you have has built in protection diodes. If not, install them on your circuit as shown. This is to prevent back currents from your DC motor. Also do not forget to put a small capacitor across the leads on your motor to reduce electronic noise and increase motor life. You might also want to refer to the tutorial on robot power regulation to help you design a better power source for your H-bridge.

It is also recommended to put a slow blow fuse after the power supply, resistors of a few 100 ohms on the gate logic, and the additional capacitors on your circuit as shown. This will prevent melting, large voltage surges, and high frequency emission.

Robots In CIS Applications

Robots have started receiving greater attention in medical/surgical applications. Tasks beyond human manipulation/precision capabilities are being trusted to assitant systems that only perform that small portion of the procedure, under human supervision. Despite intial skeptical response due to safety, and cost concerns the role of robots in surgery is likely to grow.

Surgical robots present an environment unlike most other applications where robots are applied. e.g. industrial plants. Mechanical components of surgical robots tend to be simpler, slower than their industrial counterparts, but the electronics, safety, and guidance systems are usually far more complex. A set of complex planning, guidance, and safety systems (often redundant) are involved in operating a surgical robot.

A team designing a surgical robot is faced with several difficulties. A complex system takes several years to develop, and development is often sequencial. E.g. The guidance system can not be tested until the hardware is available, and software developing and testing is highly dependent on availability of functioning hardware. Surgical robots are developed to deal with specific surgical procedures, and so each application results in the repetition of the design cycle.

A modular system allows software development to be independent of hardware design. It also allows existing modules to be used for new applications. It improves design clarity and testing and finally develops interfaces making interoperability between different systems easier.

There are several ways to develop modular/flexible software to control a robot: use/develop a programming language with all the facilities of object oriented design. But this would create yet another language, with a learning curve and user acceptance issues. An alternative approach is to develop interfaces, and implementations of the same in an acceptable programming language. This provides libraries that can be shared, swapped, and developed independently of each other. Furthermore, it allows the programming language to be changed, while preserving the interfaces (most programming languages provide ways of calling other language libraries, if need be).

The modular robot control(MRC) library is one such library. While the set of robots under consideration is mostly serial manipulators, the interface design can be easily extended to parallel architectures. The interface design is independent of the programming language, and the first implementation uses C++ classes. The library classes have a layered structure, each new Layer inheriting significant functionality from its parents.

This documentation is for the MRC library version 1.1 The class most commonly used by an application as an instantiable robot is the mrcRobot class and this should also be the base for all derived robot classes. Detailed implementation documentation exists separately.
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