mobile robots

Saturday, January 26, 2008

Robotics

Robotics is the science and technology of robots, their design, manufacture, and application. Robotics requires a working knowledge of electronics, mechanics and software, and is usually accompanied by a large working knowledge of many subjects. A person working in the field is a roboticist.

Although the appearance and capabilities of robots vary vastly, all robots share the features of a mechanical, movable structure under some form of autonomous control. The structure of a robot is usually mostly mechanical and can be called a kinematic chain (its functionality being akin to the skeleton of the human body). The chain is formed of links (its bones), actuators (its muscles) and joints which can allow one or more degrees of freedom. Most contemporary robots use open serial chains in which each link connects the one before to the one after it. These robots are called serial robots and often resemble the human arm. Some robots, such as the Stewart platform, use closed parallel kinematic chains. Other structures, such as those that mimic the mechanical structure of humans, various animals and insects, are comparatively rare. However, the development and use of such structures in robots is an active area of research (e.g. biomechanics). Robots used as manipulators have an end effector mounted on the last link. This end effector can be anything from a welding device to a mechanical hand used to manipulate the environment.

Sunday, January 20, 2008

Stepper motor

Stepper motors operate much differently from normal DC motors, which rotate when voltage is applied to their terminals. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets arranged around a central gear-shaped piece of iron. The electromagnets are energized by an external control circuit, such as a microcontroller. To make the motor shaft turn, first one electromagnet is given power, which makes the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are thus aligned to the first electromagnet, they are slightly offset from the next electromagnet. So when the next electromagnet is turned on and the first is turned off, the gear rotates slightly to align with the next one, and from there the process is repeated. Each of those slight rotations is called a "step." In that way, the motor can be turned a precise angle. There are two basic arrangements for the electromagnetic coils: bipolar and unipolar.

Stepper motors are constant-power devices (power = angular velocity x torque). As motor speed increases, torque decreases. The torque curve may be extended by using current limiting drivers and increasing the driving voltage.

Steppers exhibit more vibration than other motor types, as the discrete step tends to snap the rotor from one position to another. This vibration can become very bad at some speeds and can cause the motor to lose torque. The effect can be mitigated by accelerating quickly through the problem speed range, physically dampening the system, or using a micro-stepping driver. Motors with greater number of phases also exhibit smoother operation than those with fewer phases.

Friday, January 18, 2008

India roars

The third test match which is going between India and Australia ,shows some better performance from Indian side. Though the couple of wickets have fallen early in the morning, they keep total to be running for their target total. Sehwag turned into this 3rd test match and his performance was quite satisfactory. First innings he scored 29 runs and second innings score 43 runs. It's a good come back after long time. Then irfan pathan who came as night watchman has stood long innnings and able to score 46 runs which aremore important runs.Now laxman and dhoni were batting beautifully and laxman had magnificiant 50 in this innings.

Anywayz letz see who will win the match ............hope for the best.....

Tuesday, January 15, 2008

sensors

A sensor is a type of transducer which uses one type of energy, a signal of some sort, and converts it into a reading for the purpose of information transfer. A mercury thermometer is an example of a sensor that converts the expansion and contraction of a volume of mercury in response to change in temperature (the signal), to a reading on a calibrated glass tube giving information about ambient temperature. Other sensors, such as a thermocouple, produce an output voltage or other electrical output which may be attached to a meter for reading a change or interpreted by another device (such as a computer). For accuracy in the application a calibration of the sensor and its output information is necessary.

Sensors are used in everyday objects such as touch-sensitive elevator buttons and lamps which dim or brighten by touching the base. There are also innumerable applications for sensors of which most people are never aware. Applications include automobiles, machines, aerospace, medicine, industry, and robotics.

A sensor's sensitivity indicates how much the sensor's output changes when the measured quantity changes. For instance, if the mercury in a thermometer moves 1cm when the temperature changes by 1°, the sensitivity is 1cm/1°. Sensors that measure very small changes must have very high sensitivities.

Monday, January 14, 2008

India at dawn side

Recently india had lost in cricket match with srilanka which was held at Australia. It looks so gloomy on that day for me beacause of their performance. Actually there is a tri-series between India, Australia, Srilanka. For the first two matches especially to India, were ended with draw due to climate problem over there.Because of that India got initially two points. Later it played with Australia and showed great performance with Australia by winning against them. Because of that win, India has stood up in first place in the comparison scoreboard. But the bad thing is, it has been lost in srilanka hands. Atcually it was a easy win for Indians but due poor bowling sreesanth india has lost it's game. Anywayz let us see who will win this series. Letz hope for the best.

Saturday, January 12, 2008

Guess and win

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All you need to do is get the lowest unique guess for your desired prize and you win.The procedure of playing and winning is quite simple.So what else your looking for? Come on switch on your internet and start guessing and have bumps of prizes.Each player is allowed to accumulate points which are redeemable for incredible gifts like designer clothes, backpacks, hand bags, accessories, and much more in the bid4prizes Rewards Store. The bid4prizes TOP PLAYERS list is comprised of the players who ultimately bid the most and receive the most points. Every time a player bids the player receives a "token" to play in the arcade. Every time a player plays an Arcade game, that player either wins a prize or receives player points. Each month every player can bid approximately 600 times. So what are you waiting for?? Time and tide waits for no man.Yes!! Time keeps rolling in their site for every product bidding. Choose the product you are going to bid and participate in their sweepstakes without delay as every seconds count.

Tuesday, January 1, 2008

mobile robots


NASA's Frogbot uses springs, linkages and motors to hop from place to place.

NASA's FIDO Rover is designed for exploration on Mars

Urbie can explore areas that are dangerous to humans


Mobile robots stand in for people in a number of ways. Some explore other planets or inhospitable areas on Earth, collecting geological samples. Others seek out landmines in former battlefields. The police sometimes use mobile robots to search for a bomb, or even to apprehend a suspect.

Mobile robots also work in homes and businesses. Hospitals may use robots to transport medications. Some museums use robots to patrol their galleries at night, monitoring air quality and humidity levels. Several companies have developed robotic vacuum.

For a mobile robot ,robotic arm plays major role in it's whole process,Robotic arms are relatively easy to build and program because they only operate within a confined area. Things get a bit trickier when you send a robot out into the world.The first obstacle is to give the robot a working locomotion system. If the robot will only need to move over smooth ground, wheels or tracks are the best option. Wheels and tracks can also work on rougher terrain if they are big enough. But robot designers often look to legs instead, because they are more adaptable. Building legged robots also helps researchers understand natural locomotion -- it's a useful exercise in biological research.Typically, hydraulic or pneumatic pistons move robot legs back and forth. The pistons attach to different leg segments just like muscles attach to different bones. It's a real trick getting all these pistons to work together properly. As a baby, your brain had to figure out exactly the right combination of muscle contractions to walk upright without falling over. Similarly, a robot designer has to figure out the right combination of piston movements involved in walking and program this information into the robot's computer. Many mobile robots have a built-in balance system (a collection of gyroscopes, for example) that tells the computer when it needs to correct its movements.

Bipedal locomotion (walking on two legs) is inherently unstable, which makes it very difficult to implement in robots. To create more stable robot walkers, designers commonly look to the animal world, specifically insects. Six-legged insects have exceptionally good balance, and they adapt well to a wide variety of terrain.

Some mobile robots are controlled by remote -- a human tells them what to do and when to do it. The remote control might communicate with the robot through an attached wire, or using radio or infrared signals. Remote robots, often called puppet robots, are useful for exploring dangerous or inaccessible environments, such as the deep sea or inside a volcano. Some robots are only partially controlled by remote. For example, the operator might direct the robot to go to a certain spot, but not steer it there -- the robot