Cornell Ranger
v1: 2001-6, v2.1: 2006-2008

Powered, 4-leg "biped," no knees. Walks on level ground. Radio-control steering.

Walked 9 km on April 3, 2008. This is an autonomous legged robot distance record.

Powered biped with knees
2003-2005

Ankle powered, minimally controlled. Walks on level ground.

Most energy-effective robot: 11 watts total, 0.2 J/N m.

Science Magazine, 2005

Passive biped with knees
v1 armless, v2 with arms (shown): 1999-2001

Passive-dynamic, two legs and knees. The most advanced passive-dynamic robot to date. Walks downhill.

J. Robotics Res., 2001

McGeer Copies
v1 & v2 (shown): 1996-2000

4 legged passive "biped" with knees. Walks downhill.

Dynamics and Stability of Systems, 2000

Tinker Toy Walkers
v1 (shown) and v2: 1996-2001

Passive biped. Can't stand stably in any configuration (even with splayed legs). Walks downhill.

Phys. Rev. Letters 1998, PRL-E 2001