Professor Jessy Grizzle at the University of Michigan designed and built Michigan’s own record-setting bipedal robot, MABEL.

The University of Michigan in Ann Arbor, with one of the top ranked Colleges of Engineering in the world, has deep and broad strengths in technologies relevant to robotics, and is home to some of the most distinguished scholars in the world. Robotics research is ongoing across several departments in the College of Engineering.

While some of the ongoing efforts are highlighted in this video, today at UM, robotic techniques are being applied for human assistance, including a prosthetic foot and an intelligent wheelchair, cutting-edge research is ongoing in perception, navigation, actuation, mechatronics, networking, learning, control, autonomy, and human-robot interaction,  and there are ground robots with wheels and tracks, walking robots, unmanned aerial vehicles with rotors and wings, underwater robots, and even some flying fish. Find out more information at http://robotics.engin.umich.edu/research.html

MORE ABOUT PROFESSOR GRIZZLE AND HIS RESEARCH:

Professor Jessy Grizzle at the University of Michigan and his PhD students design feedback algorithms for MABEL, their record-setting bipedal robot. MABEL’s feedback algorithms give it an enhanced sense of balance and the ability to walk over very uneven terrain as well as run fast.

MABEL, was designed in collaboration with Jonathan Hurst, who at the time was a PhD student Carnegie Mellon’s Robotics Institute and currently an assistant professor at Oregon State University.  MABEL is comprised of five links assembled to form a torso and two legs with knees. The legs are terminated in point feet. The planar nature of the robot is manifested in the hips, which are constrained to revolute motion in the sagittal plane. The robot is attached to a boom and hence walks or runs in a circle; when the radius is sufficiently large, this corresponds to locomotion along a straight line.

The novel aspects of MABEL, and there are many, appear in the transmission or powertrain . First of all, all of the actuators (four DC-brushless motors, two for each leg) are located in the torso, so that the legs are as light as possible; this is done for running efficiency (In most other robots, the knee motors are mounted on the thigh). Secondly, the actuated degrees of freedom of each leg do not correspond to the knee and the hip angles (the hip angle being the relative angle between the torso and thigh). Instead, for each leg, a collection of differentials is used to connect two motors (once again, located in the torso) to the hip and knee joints in such a way that one motor controls the angle of the virtual leg consisting of the line connecting the hip to the toe, and the second motor is connected–in series with a spring–in order to control the length (or shape) of the virtual leg.

While the mechanical design sounds quite complex, the bottom line is that these design features turn MABEL’s legs into pogo sticks, giving the robot the ability to run with a lilting gait and stomp over very rough ground, as seen in the numerous videos on Professor Grizzle’s YouTube Channel, http://www.youtube.com/user/DynamicLegLocomotion

What records has MABEL held? (1) Fastest walking robot at 1.5 m/s (3.4 mph), held from October 2009 until April 2010. (2) Fastest running robot with knees, 3 m/s (a 9 minute mile), established in August 2011. (3) Most stable walker, able to step off an unseen, 20 cm (8 inch) step without falling (established Sept. 2011). (4) First robot with a trip reflex (April 2012).

The records are fun, but the enduring contributions of the robot will be the mathematical modeling and control design that it has inspired, and the application of MABEL’s enhanced agility and balance to the development of rescue robots, for example.

Professor Grizzle is currently planning for MABEL’s successor, currently named ATRIAS. The new robot will arrive in Michigan sometime in August 2012. It will be a free-standing walker (no need for an external bar); it will be battery powered and have a wireless interface. Like MABEL, ATRIAS is being designed in collaboration with Jonathan Hurst http://mime.oregonstate.edu/research/drl/

Professor Grizzle works at the University of Michigan, College of Engineering in the Electrical and Computer Engineering (ECE) department.  For more information about Professor Grizzle click here to view his profile and webpage.

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