Sit back for a while and try to think of a few advantages our legs have over wheels in moying around. Wheels can't climb stairs. They can't also step over obstacles or gathrough narrow spaces or move on soft or uneven ground. Humans and animals can choose the foot-holds that offer the best support, specially in mountains. In fact, about half the earth's surface is such that it is very difficult for wheels to move on it. Creeping, climbing, balancing, walking and running are all possible for legged creatures.
Our legs can also bend at knees which makes adjustment easy. Therefore, a robot must be given legs so that it is able to move around easily. Making legged robots has proved to be a challenging job in roboiics. Although computers have been built into legged vehicles, the problem4 of balance, coordination and walking on rough ground have proved difficult to solve. Along with robot movement, building in natural flexiblity, manual, touch and hearing ability in robots are active areas of research in robotics these days.
Great developments have taken place in materials which are called polymers, and consist.of long chains of small molecules joined end to end. Plasticsare one k~nd of polymers used extensively in machines and devices. and so commonly even in rural areas-in the form of cups, buckets, ropes, bags, rain-coats and other clothing etc. Rubbers are alsa$olyrners. and so are ceramics from which china-ware and all kinds of insulators are made. There has been great development in this field. Ceramic car engines are being developed which mill be much lighter than the present cast steel and will be able to operate at a higher inner temperature and pressure. Engine weight may be reduced to a quarter of what it is today, anti power may be increased four times. Ceramic magnets are now in conimon use: the ratio of the magnet's force to its lueight has ken increased more than a hundred times.