Researchers take the next step in robotic technology

BY ANKIT SUR
Daily Staff Reporter
Published May 30, 2005

From building cars to exploring other planets, robots have proven to be useful partners in advancing human achievement. These magnificent machines have been the focus of many movies, in which they are depicted as mimicking their human counterparts by walking, talking and behaving like human beings.

Chelsea Trull
The robot, pictured above, imitates human walking patterns, and can reach speeds of 3.9 mph. The new technology presents the potential for many different uses in the future.(Courtesy of Artechnique Photographie)

With the latest breakthrough in robotics technology, robots may actually be capable of what many modern movies have depicted, and thus become even more indispensable to our society.

University Electrical Engineering Professor Jessy Grizzle and a team of French scientists have designed a robot called RABBIT that can perfectly mimic human ambulatory patterns.

When RABBIT is nudged it can regain its balance instantly, which prevents it from falling over like its predecessors would have done.

Grizzle and the other researchers were able to accomplish this feat due to Grizzle’s “control theory.”

“We have designed virtual constraints that synchronize the robots’ knees and hips,” Grizzle said.

According to Grizzle, when the robot starts to walk, its leg moves forward and the robot synchronizes its hips and knees in a way that prevents it from falling. A control algorithm monitors the robot’s walking motion, and adjusts the legs accordingly.

The leg that moves forward then becomes the load bearing leg, and the other leg swings forward about the knee, which acts as a pivot — the same way a human would take a step.

Using this simple technique, the robot is able to walk gracefully at 3.9 mph.

“We were able to design a control algorithm that was able to mimic human walking by defining the way humans walk into a set of equations, which we then translated into control algorithms that controls the robots ability to walk and balance,” Grizzle explained.

While current bi-pedal robots have large feet to avoid falling over, RABBIT has stilt-like legs instead of feet.

RABBIT’s predecessors had large feet to achieve proper balance, due to a lack of knowledge in walking dynamics. However, Grizzle said that RABBIT’s more complex algorithm, which is the result of more thorough analysis, helps remedy the stiff walking pattern that other robots display.

Grizzle’s work has a promising future in the development of human prosthetics.

“We can use what we have learned in developing RABBIT and apply it to human beings,” Grizzle said.

Eric Westervelt, an engineering professor at Ohio State University, is currently working to apply the knowledge learned in developing RABBIT to the design of human prosthetics, Grizzle said.

Westervelt said the theory used by the controllers of RABBIT will be helpful in designing prosthetics.

Companies that produce prosthetics, such as Ohio Willow Wood, have taken interest in Westervelt’s work and plan to use the findings of his analysis to build a human prosthetic.

Westervelt joined Grizzle and the team of French scientists in 2000, when he was a Rackham student at the University.

Grizzle joined the team in 1998, and he plans to build a robot like RABBIT at the University because RABBIT currently resides in France.

“We plan to start building a robot that will be able to walk and run more efficiently than RABBIT in three or four months, and it should be completed in a year,” Grizzle said.