Origami-based integration of robots that sense, decide, and respond

Origami robots, constructed by folding 2D sheets into 3D structures, offer advantages over traditional robots including rapid prototyping, high specific strength, built-in compliance, low cost, and high accessibility. However, nearly all existing origami robots rely on rigid semiconductor-based electronics for sensing, control, and actuation, limiting their potential. This dependence increases complexity, weight, and vulnerability to environmental factors. The mismatch in stiffness between rigid electronics and compliant origami bodies also poses challenges in design and fabrication. The need for external electronics hinders the accessibility and applicability of origami robots, particularly in resource-constrained environments or disaster relief scenarios. This research aims to overcome these limitations by developing a method for embedding sensing, computing, and actuation directly into compliant materials, creating a new class of autonomous origami robots while retaining the benefits of origami-based fabrication. Previous research has explored integrating smart materials into origami structures for various functionalities, but creating fully integrated autonomous systems with embedded sensing, computing, and actuation within compliant materials has remained a significant challenge. This challenge stems from the lack of suitable computing elements that can interface with existing sensing and actuating components, along with high resistance and energy loss in current architectures. This paper addresses this challenge by presenting a novel approach.

The paper reviews existing research on origami robots and the integration of smart materials into origami structures. It highlights the limitations of current origami robots' reliance on rigid semiconductor-based electronics and the need for a more integrated approach using compliant materials. The authors cite numerous papers on origami robotics, focusing on the advantages and disadvantages of existing designs. They also discuss efforts to integrate smart materials like shape memory alloys and conductive polymers into origami structures for sensing and actuation. The review emphasizes the lack of integrated computing capabilities within these designs, motivating the need for a new approach that combines sensing, computing, and actuation in a single, compliant platform. The literature review underscores the broader trend toward non-traditional computing approaches across various fields, such as soft robotics and microfluidics, creating a context for the proposed research.

The core of the methodology is the development and integration of an Origami Multiplexed Switch (OMS). The OMS, acting as a 2-to-1 multiplexer, selects between two input signals based on a selection signal. It comprises a bistable beam and two Conductive Super-Coiled Polymer (CSCP) actuators. The CSCP actuators, acting as thermal actuators, drive the bistable beam between two stable states, controlling the on/off states of electrical poles on the beam. The bistable beam's snap-through behavior provides binary switching and reduces energy consumption. The design of tabs on the bistable beam is crucial for achieving a high ON/OFF ratio (~10⁶). The OMS is characterized through experiments to determine gate delay and its dependence on voltage and cooling conditions. A simplified analytical model is developed to capture the complex interaction of mechanical, thermal, and electrical properties of the OMS. The OMS's robustness to noise is also demonstrated experimentally. Building upon the OMS, the authors design and implement fundamental logic gates (NOT, AND, OR) and combinational logic gates (NAND, NOR). The low internal resistance of the OMS allows for cascading multiple gates without intermediate circuitry. A non-volatile memory bit is also constructed using a modified OMS configured as a set-reset latch, showcasing the ability to store information persistently. Finally, the authors demonstrate the integration of these components into three autonomous origami robots: a flytrap-inspired robot, a self-reversing legged robot, and a wheeled robot with reprogrammable trajectories. The fabrication of the CSCP actuators involves a three-step process: coiling conductive yarn, annealing, and stabilization. Origami devices are fabricated manually from patterned polyester film, copper tape, and assembled CSCP actuators. Characterization involves using a DC power supply, recording current and voltage, and analyzing displacement from camera footage. Active cooling is implemented to reduce gate delay.

The key findings demonstrate the successful integration of sensing, computing, and actuation within compliant origami materials. The origami multiplexed switch (OMS) serves as a foundational element, enabling the creation of functional logic gates and a non-volatile memory bit. The OMS demonstrates a high ON/OFF ratio and robustness to noise. The ability to cascade multiple OMSs to create more complex circuits is proven, allowing for greater computational power. The successful implementation of fundamental and combinational logic gates showcases the feasibility of building complex computational systems using origami components. The development of a 1-bit memory device that retains information even after a power outage is a crucial advancement for enabling autonomous operation. Three distinct autonomous origami robots are presented to validate the integrated system's performance in real-world scenarios. The flytrap-inspired robot demonstrates the ability to distinguish between moving and stationary objects, closing its leaves only upon detecting a moving stimulus. The self-reversing legged robot showcases collision avoidance capabilities, reversing direction when encountering an obstacle. The wheeled robot with reprogrammable trajectories exemplifies the successful implementation of origami memory for controlling locomotion along pre-defined paths. All three robots function reliably even under adverse environmental conditions (magnetic fields, RF signals, ESD, mechanical deformation), demonstrating the robustness of the integrated origami approach compared to its semiconductor-based counterparts. The work also quantifies the advantages of the method, specifically improved weight and cost, in comparison to traditional designs.

The research successfully addresses the challenge of creating fully integrated autonomous origami robots. The proposed method offers a viable alternative to traditional semiconductor-based approaches, mitigating limitations in weight, complexity, and environmental robustness. The OMS, the core of the system, demonstrates impressive performance in terms of switching speed, energy efficiency, and noise immunity. The ability to create complex logic circuits and non-volatile memory opens up possibilities for more sophisticated robot behaviors. The successful integration of these components into functional robots demonstrates the practical application of the proposed methodology. The robustness demonstrated in adversarial environments highlights the potential of this technology for applications in extreme conditions where traditional electronics may fail. The findings contribute significantly to the field of origami robotics, pushing the boundaries of autonomy and integration within compliant systems. The research opens new avenues for exploring more complex robot behaviors, such as implementing finite state machines or even Turing machines within the origami framework.

This research presents a significant advancement in origami robotics by introducing a fully integrated approach to autonomous systems. The development and characterization of the origami multiplexed switch (OMS) and its application in creating logic gates, memory, and autonomous robots showcase the potential for creating sophisticated, robust, and environmentally resilient robots using compliant materials. Future research could explore the development of more complex origami computing architectures, expanding the capabilities of these robots. Investigating alternative materials and actuation mechanisms could further enhance performance and efficiency. The integration of more advanced sensors and the development of more sophisticated control algorithms would allow for even more complex robot behaviors and capabilities.

The current study focuses on relatively simple robot designs. While the demonstrated robots showcase the capabilities of the integrated system, more complex robots may require further development and optimization. The switching speed of the OMS, although improved through active cooling, could be further enhanced. The current memory capacity is limited; scaling up the memory would require further engineering. The manual manipulation of the memory writing in the wheeled robot is a limitation; automating this process would be beneficial for greater autonomy. Furthermore, the study's focus on certain types of environmental factors does not account for a complete range of possible conditions.