Computers Today, November 1-15, 2000; Marvels; Honda's Walking Robot

Honda's Walking Robot Machines that take on human form have always enthralled us. The entertainment business has been banking on this popular fascination for decades. The ultimate goal among those associated with robotics is to create a replica of the human species, or even better-"robo sapiens". That dream may still be far away-but intelligent and mobile robots are a reality today. Honda Motors recently unveiled its humanoid robot P3, the latest version of the two-legged machine that the automobile maker has been developing since 1986. P3 that looks like an astronaut in a spacesuit is a robot that will help people in daily activities, claims Honda. The robot can walk just like humans-it can move up and down the stairs, or through a room full of furniture without banging into it or falling on its head. Experts hail P3 as the highest-performing bipedal robot in the world.

Two-legged robots are difficult to develop as they involve an array of high technologies, like sensors, to maintain stable walking. Honda's initial efforts at making such a robot resulted in the E2 model, developed after an analysis of an ostrich's movements. It was 132 cm (4.3 ft) tall and weighed 67.7 kg. But the head was disproportionately big, and the E2 fell over easily, unable to balance the body sections. After a number of improvements, Honda came up with humanoid-type robots with synchronised arm and leg movements-the P1, the P2, and now the P3.

What distinguishes P3 from its prototypes is the sheer balance incorporated in the weight of various body parts, their architecture and the technology that supports their functioning. The robot is 1.6 metres tall, has a shoulder width of 60 centimetres, a depth of 55 centimetres, and weighs 130 kilograms. The skeleton is made of magnesium, and the movements are powered by servomotors. P3 can work for up to 25 minutes on a battery charge, and carry weights of up to nine kilograms per hand effortlessly.

The maximum walking speed is approximately two kilometres per hour. A four-processor computer contained in the rucksack is in charge of controlling the balance as well as coordinating its extremities during coordinated movements. Two video cameras, which function independently of one another, are located under the visor and a microphone and speaker are also on board. In terms of its dimensions and technical data, it is already well suited for everyday human surroundings.

P3's proportions and the position of its joints are adapted from the human body. It possesses 16 joints, which due to their degree of flexibility, enable complex movements. An important difference in comparison with the human apparatus is that the spinal column is missing: P3's back is rigid. The robot has, therefore, been equipped with relatively long arms in order to reach the floor on bent knees. The high mobility of the joints as well as the cleverly constructed balance control mechanisms enables P3 to stand on one leg, walk sideways or walk leaning forward.

P3's outstanding balancing act becomes evident when it climbs up a flight of stairs on its own. The robot does this with an admirable steadiness. It is even more difficult to come back down a flight of stairs due to the fact that the feet have to absorb and balance out very high forces, but this is also not a problem for P3.

Despite a built-in camera, P3 is currently not capable of recognising the height of a step independently and to automatically adapt its gait. Nevertheless, even today, P3's abilities clearly illustrate the potential of future bipedal robots.

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