Reductions in size and weight were the key advances made with Honda’s third prototype humanoid robot, which was completed in September 1997. Reductions were made possible by changing component materials and by decentralizing its control system, which was made up of two Microspec II (110 MHz) CPUs. The P3 is considered the world’s first completely independent two-legged humanoid walking robot (2km/h).
It had the same sensors as the P2, 30 degrees of freedom (2 legs x6, 2 arms x7, 2 hands x1, neck x2), stood 160cm (5’3″) tall, weighed 130kg (286 lbs), and could hold 2kg (4.4 lbs) per hand. Lower power consumption meant it was able to operate for approximately 25 minutes. Its smaller size was better suited for use in a human-oriented environment. It would be showcased regularly between 1997 and 1999 leading up to the unveiling of ASIMO. As with the P2, hobby kit maker Wave put out a pair of model replicas based on the P3 due to its popularity. Although the kit is discontinued, one might still be able to purchase one online for around $20.
The P3 was loaned to Japan’s National Institute of Advanced Industrial Science and Technology (AIST) in 1998 to help kick start their Humanoid Robot Project. A yellow version of the robot was called HRP-1, which would later be customized with a better processor to unite both the upper body and lower body controls (HRP-1S). Notable demonstrations included teleoperation of the P3 driving a construction crane in the rain, which required the P3 to don a raincoat. AIST and Kawada Industries would go on to develop their own unique humanoid robots which continue to be used by Japanese researchers.
Further efforts were made to reduce size and weight, and improve dynamic performance and operability. Development on the fourth prototype (P4) continued from 1997-1999, but was kept a secret until March 2010, when it appeared at the Motegi Twin Ring Exhibition Hall. It was the same height as the P3 at 160cm (5’3″) tall, but weighed significantly less at only 80kg (176 lbs). It also had 34 degrees of freedom (2 more per hand compared to the P3).
Soon Honda would be ready to reveal a more fully optimized model that would abandon the prototype prefix.
Video (P3 presentation):
Video (Honda TV commercial):
Video (P3 RoboCup Promo):
Video (Assorted P3 clips):