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Cooking up success in robotics research

By Lara Palmquist '13
September 11, 2012

This summer a team that included (from left) Sarah Beth Sivanich '13, Associate Professor of Physics Jason Engbrecht, Nate Hillson '14, and Mohamed Haji '13 (not pictured) designed and constructed a robotic arm named Carol that can make cookies.

When Sarah Beth Sivanich '13 speaks of her robotics research this summer, she refers to a member of her lab named Carol with obvious endearment.

Yet while Carol can measure, weigh, and slice as any faithful assistant should, she isn't a standard member of Sivanich's research team. She's a highly sensitive robotic arm.

This summer a group of St. Olaf students led by Associate Professor of Physics Jason Engbrecht set out to take robots from closely controlled industrial environments into situations that will allow them to interact with humans. Working as part of the St. Olaf Collaborative Undergraduate Research and Inquiry (CURI) program, the robotics team — which includes Sivanich, Mohamed Haji '13, and Nate Hillson '14 — wanted to create a robot that could complete tasks requiring a variety of equipment and movements.

"What better tools than kitchen utensils, and what better objective than making cookies?" Sivanich says.

They decided that assembling sugar cookies was the ideal way to put Carol through her paces — measuring, scooping, pouring, mixing, and cutting through dough in quick succession.

The collaboration of Carol
Each member of the robotics team focused on a different aspect of Carol. Haji worked on modifying standard kitchen tools to be compatible with the robotic arm, as well as on a force-torque sensor mounted on the end of Carol's wrist. This sensor provides the robot with feedback crucial for scooping and adding ingredients in the appropriate amounts.

Through Haji's work, Carol is able to alternate between measuring lightweight flour and dense sugar granules with accuracy and ease. The force sensor on Carol's wrist also aids the robotic arm in performing tasks requiring pressure feedback, such as using the knife Haji created to fit Carol's arm for slicing through dough.

Hillson focused on the inverse kinematics and modeling movements of the robotic arm, which allow Carol to relocate throughout a work space. Using complex computer programming, Hillson provided Carol with the accurate mobility the robot requires to add each ingredient in the appropriate order. His work also equipped Carol with the ability to measure the length of a roll of dough and to divide it into appropriately sized pieces for baking.

Sivanich worked on the vision component of the system. Her focus was to provide Carol with visual feedback, thereby allowing the robot to locate ingredients throughout the work area. To achieve this objective, Sivanich designed a coordinate program that connects a specially formatted camera to the movements of the robotic arm.

"These techniques for measurement of forces, arm motion, and vision collaboration laid a strong foundation for future work," says Engbrecht. Combined, the individual efforts of each team member resulted in sugary success: cookies from Carol.

A foundation for the future
The experience also rewarded the students with invaluable exposure to robotics research. "This opportunity has given me a taste of what research in the physics field is really like," Sivanich says, adding that she gained technical skills that will aid her in future pursuits.

While a version of Carol won't likely be found in kitchens anytime soon, the robot is an effective tool to further the understanding and application of intelligent robotic arms. Sivanich hopes that the work of the robotics team this summer will contribute to the rapidly developing notion of "everyday robotics."

"Many roboticists are working on techniques for robots to manipulate complex environments such as a home or workplace," says Engbrecht. "Our work is one piece of that project that focuses on the use of common tools."

In the months ahead the research team will continue to engineer their techniques to achieve more efficient results. Using a second robotic arm named Dave, which can better withstand the high forces required for mixing dough, they hope to accomplish further culinary success. The rewards of robotics research have never seemed so sweet.

Watch a video of Carol in action.

Contact Kari VanDerVeen at 507-786-3970 or