The DIY Bipedal Robot That Paved the Way for Modern Robotics

In 1987, Richard Greenhill, a British photographer fascinated by robotics, embarked on an ambitious project to build a life-size humanoid robot capable of performing useful tasks, such as carrying luggage. Despite having no formal training in robotics, Greenhill was determined to bring his vision to life. He started working on the project in his attic, where he gathered a group of like-minded individuals, known as the Shadow Group, to collaborate and share ideas.

The Shadow Group's main project was the two-legged Shadow Walker. Greenhill and his friend David Buckley, a robotics and animatronics expert, designed the robot's skeleton based on human bone structure and muscle movement. The robot's skeleton was greatly simplified, with only one bone in the lower leg and a single wide toe on each foot.

The ankle's double-axis design allowed for two degrees of movement, while the knee had no complicating kneecap. To control the robot's movement, Greenhill opted for compressed air to extend and contract 28 'air-muscles,' a version of the McKibben muscle invented in the 1950s. The Shadow Walker stood 168 centimeters tall, 46 cm wide, and weighed about 38 kilograms.

The group successfully got the robot to stand up reliably and balance itself, and it could even regain its center if pushed slightly. However, walking proved to be a significant challenge. Rich Walker, who joined the group as a teenager, wrote software to help the robot stand, focusing on using neural networks to solve balancing problems.

Despite the group's efforts, the robot struggled with hardware issues, including unreliable sensors and valves, as well as its overall fragility. The Shadow Group's project coincided with significant developments in the field of robotics. In 1986, Honda began working on its experimental humanoid robots, eventually unveiling the P2 in 1996.

The P2 was the first humanoid capable of stable, autonomous walking, paving the way for the development of the groundbreaking ASIMO. The 1st International Robot Olympics, held in 1990, brought together robots from around the world to compete in various events. The Shadow Walker participated in the Olympics but failed to take more than a few steps, ultimately losing to the Cardiff University Biped.

The legacy of the Shadow Walker lives on through Shadow Robot, a company founded by the Shadow Group in 1997. Today, Shadow Robot specializes in durable robot hands, which have become testbeds for dexterity. The company's hands feature 20 motors, allowing for precise movement with 24 degrees of freedom.