Cagdas Denizel Onal

Intelligence, embedded in the mechanics in the form of active compliance provides safety and adaptability for a robot to interact with real-world environments. With large degrees of freedom and unique kinematics, flexible mechanisms can adjust their body to perform various tasks. As a step towards bridging the gap between man-made machines and their biological counterparts, we developed a class of soft mechanisms that can undergo shape change and locomotion under pneumatic actuation. Sensing, computation, communication and actuation are embedded leading to an active soft material. We developed a "Pneumatic Battery" by the catalyzed decomposition of hydrogen peroxide into oxygen and water for actuation power and Electropermanent Magnet Valves to drive the Fluidic Elastomer Actuators. We show instances of such mechanisms and demonstrate shape changing, and autonomous, sensor-based locomotion using distributed control. The flexible system is accurately modeled by an equivalent mass-spring model. We derive a distributed feedback control law that lets a circular robot made of flexible components roll itself and climb up inclinations. These mechanisms and algorithms may provide a basis for creating a new generation of bioinspired soft robots that can negotiate openings and manipulate objects with an unprecedented level of compliance and robustness.

The ability to print robots introduces a fast and low-cost fabrication method to modern, real-world robotic applications. To this end, we employ laser-machined origami patterns on polymer sheets to build a new class of robotic systems for mobility and manipulation. Origami is suitable for printable robotics as it uses only a flat sheet as the base structure for building complicated functional shapes, which can be utilized as robot bodies. An arbitrarily complex folding pattern can be used to yield an array of functionalities, in the form of actuated hinges or active spring elements. For actuation, we use compact NiTi coil actuators placed on the body to move parts of the structure on-demand.

Meshworm is an earthworm-inspired robot designed by Prof. Sangbae Kim. The robot exhibits peristaltic locomotion using a sequential antagonistic motion of a flexible braided mesh-tube structure with NiTi coil actuators. To drive this robot, we designed an iterative learning controller to optimize performance, which is quantified to define the trade-off between the speed and power consumption such that the performance increases with increasing speed and decreasing power usage. A small form-factor custom PCB and a lightweight battery are used to achive an embedded controller. Using the actuation period as the control input, the iterative learning controller adjusts the actuation timings in the next step to maximize performance, in a steepest-descent manner.

Interacting with matter at the micro/nano-scale may allow us to study and utilize the interesting physical phenomena inherent to small scales. Using a custom atomic force microscope (AFM) setup, we designed manipulation systems and algorithms that enable micro/nano-scale interaction in teleoperated and automated settings. Augmenting theory with experimental data, we were able to obtain the full 3-D force vector from the coupled force readings in AFM for the first time to fully experience the nanoscale forces. On the other hand, with a number algorithms and controllers, we developed a fully-automated closed-loop particle manipulation system that constructs 2-D structures from simple micro/nano-objects. Using force feedback, we performed closed-loop automated nanoparticle manipulation for the first time.