Honda P1

What it was

The P1 was the first humanoid robot model in Honda's P series, built during a research phase that ran from 1993 to 1997 ^[1]. It was a laboratory machine rather than a product: something engineers built in order to find out what a two-legged robot with a body and arms could do. It stood 1,915 mm tall and weighed 175 kg ^[1]. The height is roughly that of a tall adult; the weight is far greater, a reminder that a walking machine of this kind carries a heavy frame, many motors and many joints.

Where it came from

Honda's earlier work in the P series had concentrated on two-legged, or bipedal, legs. The P1 added a torso and arms to those legs, which is how Honda describes the step toward a truly humanoid robot ^[1]. A pair of walking legs is a locomotion system; a torso and arms turn it into a machine that can face the world the way a person does, with something to reach and hold. Honda calls the P1 the company's first prototype model, the machine that came before the wireless P2 ^[2].

How it was put together

The defining feature of the P1 is that it was not self-contained. It used an external power source and an external computer ^[1]. Power and computing both lived outside the body, reaching the robot through a connection. That arrangement is typical of early walking robots: the motors that drive the joints draw a great deal of current, and the control calculations are heavy, so it is easier to keep the supply and the computing on the ground while the machine on legs is being tested. Honda describes the P1 in exactly these terms — a first prototype with an external power source and computer, followed by the wireless P2 ^[2].

What it could do

The P1 could turn a switch on and off, grab a doorknob, and carry an object around ^[1]. Each of these is trivial for a person and demanding for a machine. Turning a switch means reaching to a point in space and applying a small, controlled force. Grabbing a doorknob means closing a hand on an object and holding it. Carrying something around means doing all of that while walking, so that the arms and the legs have to agree with each other. Honda used the P1 to research precisely this kind of action, in which arms and legs work in a coordinated way ^[1].

Why it matters

The P1 marks the point where Honda's walking legs became a humanoid robot — a machine with a head-height body, two arms and two legs, rather than a pair of legs with nothing above them ^[1]. Its limits are just as instructive. Because power and computing stayed outside the body, everything the P1 did depended on a connection to equipment on the ground; the machine could not walk away and keep working. The later P2, which Honda describes as wireless, removed that dependence ^[2]. Read in sequence, the P1 shows what the first step looks like: a heavy, tethered prototype used to learn how arms and legs can move together, before the same problems are solved inside the robot itself.