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Publication Kinegami: Open-source Software for Creating Kinematic Chains from Tubular Origami(Springer, 2024-07-16) Feshbach, Daniel AdamArms, legs, and fingers of animals and robots are all examples of “kinematic chains" - mechanisms with sequences of joints connected by effectively rigid links. Lightweight kinematic chains can be manufactured quickly and cheaply by folding tubes. In recent work [Chen et al. 2023], we demonstrated that origami patterns for kinematic chains with arbitrary numbers of degrees of freedom can be constructed algorithmically from a minimal kinematic specification (axes that joints rotate about or translate along). The work was founded on a catalog of tubular crease patterns for revolute joints (rotation about an axis), prismatic joints (translation along an axis), and links, which compose to form the specified design. With this paper, we release an open-source python implementation of these patterns and algorithms. Users can specify kinematic chains as a sequence of degrees of freedom or by specific joint locations and orientations. Our software uses this information to construct a single crease pattern for the corresponding chain. The software also includes functions to move or delete joints in an existing chain and regenerate the connecting links, and a visualization tool so users can check that the chain can achieve their desired configurations. This paper provides a detailed guide to the code and its usage, including an explanation of our proposed representation for tubular crease patterns. We include a number of examples to illustrate the software’s capabilities and its potential for robot and mechanism design.Publication Re-programmable Matter by Folding: Magnetically Controlled Origami that Self-Folds, Self-Unfolds, and Self-Reconfigures On-Demand(Springer, 2024-07-24) Unger, Gabriel; Sung, CynthiaWe present a reprogrammable matter system that changes shape in a controllable manner in real-time and on-demand. The system uses origami inspired fabrication for self-assembly and repeated self-reconfiguration. By writing a magnetic program onto a thin laminate and applying an external magnetic field, we control the sheet to self-fold. The magnetic program can be written at millimeter resolution over hundreds of programming cycles and folding steps. We demonstrate how the same sheet can fold and unfold into multiple shapes using a fully automated program-and-fold process. Finally, we demonstrate how electronic components can be incorporated to produce functional structures such as a foldable display. The system has advantages over existing programmable matter systems in its versatility and ability to support potentially any folding sequence.Publication RAPID FABRICATION OF CUSTOMIZABLE MXENE/POLYDOPAMINE (MXPDA) ELECTRODES(2024-05-17) Daryl HurwitzIn the evolving field of neuroelectronics implants, several significant challenges persist. The rigidity of traditional devices often lead to substantial tissue damage and immune reactions, highlighting the urgent need for flexible, biomimetic designs that integrate more harmoniously with neural tissues, thereby enhancing biocompatibility and long-term stability. Most commercial neural implants are not customizable and feature a limited number of electrodes, which constrains the scope of neural data that can be captured. This limitation calls for the development of scalable technologies that can achieve higher spatial resolutions. Efficient wireless power and data transfer technologies are also essential to support fully implantable, untethered neural interfaces. Current implants generally lack the ability to incorporate multiple recording and stimulation modalities, restricting their application in diverse scientific studies. The development of multimodal interfaces could address this limitation, enabling more detailed studies of neural structure and function. This thesis explores the innovative use of MXene, specifically the two-dimensional nanomaterial TI3C2Tx, in conjunction with polydopamine (PDA) to develop customizable microelectrode arrays (MEAs) that can be rapidly fabricated for use in surgical settings. MXenes are selected for their exceptional conductivity, flexibility, and biocompatibility-qualities essential for effective neural interfaces. The addition of PDA enhances these interfaces’ mechanical and environmental stability while maintaining their excellent electrical properties. This research presents a novel method for the quick production of MEAs that can be adapted to individual surgical requirements potentially a day prior to or on the day of surgery, ultimately facilitating precise electrode placement for optimized neural recording and stimulation. By addressing the significant challenges of existing bioelectronic interfaces—such as the need for stable, safe, and functional integration with soft biological tissues—this thesis demonstrates a scalable approach to fabricate devices that combine the unique optical, electronic, and biocompatible properties of carbon-based nanomaterials. The outcomes of this work are expected to contribute significantly to the fields of neurology and bioelectronics by providing a robust platform for the advanced study of brain function across various spatial and temporal scales. This could lead to improved understanding and management of neurological conditions, thereby aligning with the broader goals of advancing neuroscientific research and clinical neurology.Publication Origami-Inspired Bistable Gripper with Self-Sensing Capabilities(7th IEEE-RAS International Conference on Soft Robotics (Robosoft) 2024, 2024-04) Kim, Christopher Y; Yang, Lele; Anbuchelvan, Ashwath; Garg, Raghav; Milbar, Niv; Vitale, Flavia; Sung, CynthiaAn origami-inspired bistable gripper, featuring a dual-function custom PET linear solenoid actuator that acts both as an actuator and a sensor, is presented. Movements in the permanent magnet plunger, which is directly mounted to the gripper, create induced electromotive force (emf) in the solenoid, and these induced emf measurements are used to detect snap-through actions and light contacts on the gripper. The fabrication methods for the gripper, actuator, and a gel-free soft wearable EMG electrode are outlined, and the actuator’s self-sensing method utilizing the time-integral of the induced emf measurements are explored. Because a self-sensing actuator eliminates the need for extra sensors, it allows for further miniaturization of the robot while maintaining its compactness and lightweight design. The paper also introduces a full humanin- the-loop system, allowing users to open or close the gripper with their biceps via a wearable EMG electrode. This system bridges human intent with robotic action, offering a more intuitive interaction model for robotic control.Publication Online Optimization of Soft Manipulator Mechanics via Hierarchical Control(2024) Misra, Shivangi; Sung, CynthiaActively tuning mechanical properties in soft robots is now feasible due to advancements in soft actuation technologies. In soft manipulators, these novel actuators can be distributed over the robot body to allow greater control over its large number of degrees of freedom and to stabilize local deformations against a range of disturbances. In this paper, we present a hierarchical policy for stiffness control for such a class of soft manipulators. The stiffness changes induce desired deformations in each segment, thereby influencing the manipulator’s end-effector position. The algorithm can be run as an online controller to influence the manipulator’s stable states – as we demonstrate in simulation – or offline as a design algorithm to optimize stiffness distributions – as we showcase in a hardware demonstration. Our proposed hierarchical control scheme is agnostic to the stiffness actuation method and can extend to other soft manipulators with nonuniform stiffness distributions.Publication ELECTRONICS DESIGN AND VERIFICATION FOR ROBOTS WITH ACTUATION AND SENSING REQUIREMENTS(ASME, 2023-08-29) Chen, Dongsheng; Huang, Zonghao; Sung, CynthiaRobot design is a challenging problem involving a balance between the robot’s mechanical design, kinematic structure, and actuation and sensing capabilities. Recentwork in computational robot design has focused on mechanical design while assuming that the given actuators are sufficient for the task. At the same time, existing electronics design tools ignore the physical requirements of the actuators and sensors in the circuit. In this paper, we present the first system that closes the loop between the two, incorporating a robot’s mechanical requirements into its circuit design process. We show that the problem can be solved using an iterative search consisting of two parts. First, a dynamic simulator converts the mechanical design and the given task into concrete actuation and sensing requirements. Second, a circuit generator executes a branch-and-bound search to convert the design requirements into a feasible electronic design. The system iterates through both of these steps, a process that is sometimes required since the electronics components add mass that may affect the robot’s design requirements. We demonstrate this approach on two examples – a manipulator and a quadruped – showing in both cases that the system is able to generate a valid electronics design.Publication CurveQuad: A Centimeter-Scale Origami Quadruped that Leverages Curved Creases to Self-Fold and Crawl with One Motor(IEEE/RSJ, 2023-10-01) Feshbach, Daniel AdamWe present CurveQuad, a miniature curved origami quadruped that is able to self-fold and unfold, crawl, and steer, all using a single actuator. CurveQuad is designed for planar manufacturing, with parts that attach and stack sequentially on a flat body. The design uses 4 curved creases pulled by 2 pairs of tendons from opposite ends of a link on a 270° servo. It is 8 cm in the longest direction and weighs 10.9 g. Rotating the horn pulls the tendons inwards to induce folding. Continuing to rotate the horn shears the robot, enabling the robot to shuffle forward while turning in either direction. We experimentally validate the robot's ability to fold, steer, and unfold by changing the magnitude of horn rotation. We also demonstrate basic feedback control by steering towards a light source from a variety of starting positions and orientations, and swarm aggregation by having 4 robots simultaneously steer towards the light. The results demonstrate the potential of using curved crease origami in self-assembling and deployable robots with complex motions such as locomotion.Publication Clifford Algebras, Clifford Groups, and a Generalization of the Quaternions: The Pin and Spin Groups(2013-11-09) Gallier, Jean HOne of the main goals of these notes is to explain how rotations in Rn are induced by the action of a certain group, Spin(n), on Rn, in a way that generalizes the action of the unit complex numbers, U(1), on R2, and the action of the unit quaternions, SU(2), on R3 (i.e., the action is denied in terms of multiplication in a larger algebra containing both the group Spin(n) and R(n). The group Spin(n), called a spinor group, is defined as a certain subgroup of units of an algebra, Cln, the Clifford algebra associated with Rn. Since the spinor groups are certain well chosen subgroups of units of Clifford algebras, it is necessary to investigate Clifford algebras to get a firm understanding of spinor groups. These notes provide a tutorial on Clifford algebra and the groups Spin and Pin, including a study of the structure of the Cliord algebra Clp;q associated with a nondegenerate symmetric bilinear form of signature (p; q) and culminating in the beautiful \8-periodicity theorem" of Elie Cartan and Raoul Bott (with proofs).Publication A Vision-Based Formation Control Framework(2002-10-01) Das, Aveek K.; Kumar, R. Vijay; Fierro, Rafael; Ostrowski, James P.; Taylor, Camillo J; Spletzer, JohnWe describe a framework for cooperative control of a group of nonholonomic mobile robots that allows us to build complex systems from simple controllers and estimators. The resultant modular approach is attractive because of the potential for reusability. Our approach to composition also guarantees stability and convergence in a wide range of tasks. There are two key features in our approach: 1) a paradigm for switching between simple decentralized controllers that allows for changes in formation; 2) the use of information from a single type of sensor, an omnidirectional camera, for all our controllers. We describe estimators that abstract the sensory information at different levels, enabling both decentralized and centralized cooperative control. Our results include numerical simulations and experiments using a testbed consisting of three nonholonomic robots.Publication Integrating Human Inputs with Autonomous Behaviors on an Intelligent Wheelchair Platform(2007-04-01) Parikh, Saranghi P; Grassi, Valdir; Kumar, R. Vijay; Okamoto, JunResearchers have developed and assessed a computer-controlled wheelchair called the Smart Chair. A shared control framework has different levels of autonomy, allowing the human operator complete control of the chair at each level while ensuring the user's safety. The semiautonomous system incorporates deliberative motion plans or controllers, reactive behaviors, and human user inputs. At every instant in time, control inputs from three sources are integrated continuously to provide a safe trajectory to the destination. Experiments with 50 participants demonstrate quantitatively and qualitatively the benefits of human-robot augmentation in three modes of operation: manual, autonomous, and semiautonomous. This article is part of a special issue on Interacting with Autonomy.