Publication Date


Document Type


First Advisor

Ryu, Ji-Chul

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Mechanical Engineering


As we have witnessed through an unprecedented pandemic crisis, a lack of or decreased level of social interactions could have a negative impact on people's mental health. Ample evidence indicates that similar phenomena take place in rodents as socially isolated rodents display a high level of stress and cognitive declination. While spherical robots have recently drawn significant interest in many areas such as education, entertainment, and surveillance due to their ability to move instantaneously in any direction, the objective of this thesis is to design and fabricate a small-sized, self-locomotive omnidirectional robot to provide those animals with physical interactions as means of alleviating the detrimental effects of social isolation. As our target animals are as small as a mouse, the size of the spherical robot aimed to be less than 48 mm in diameter. In addition, to facilitate the design and fabrication process, off-the-shelf components were determined to be used. We used an 18 x 32 mm highly integrated ESP32 microcontroller board that has wireless connectivity and an in-built LIPO battery charger. An 18 x 10 mm dual motor driver is connected to the microcontroller to control two miniature brushed DC motors. A 25 x 13 mm 9-axis IMU sensor is mounted and communicates with the microcontroller for the position and orientation estimation of the spherical robot. The design process was mainly driven by the size constraints of the spherical robot and components. A two-wheeled differential drive is chosen for the robot’s internal locomotion mechanism as the mechanism is relatively easy to model, fabricate, and control. All the parts, including the shell, were fabricated using a 3D printing process. The fabricated spherical robot was tested to generated straight-line and circular motions. An overhead camera is utilized to track the real-time position of the spherical robot using an OpenCV color tracking with a frame rate of up to 120 Hz with 320 x 240 pixel resolution. The experiments were conducted under open-loop control and the results confirms the feasibility of the spherical robot design.


59 pages




Northern Illinois University

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