Biology and bioinspiration of soft robotics : actuation, sensing, and system integration

Organisms in nature grow with senses, nervous, and actuation systems coordinated in ingenious ways to sustain metabolism and other essential life activities. The understanding of biological structures and functions guide the construction of soft robotics with unprecedented performances. However, despite the progress in soft robotics, there still remains a big gap between man-made soft robotics and natural lives in terms of autonomy, adaptability, self-repair, durability, energy efficiency, etc. Here, the actuation and sensing strategies in the natural biological world are summarized along with their man-made counterparts applied in soft robotics. The development trends of bioinspired soft robotics toward closed loop and embodiment are proposed. Challenges for obtaining autonomous soft robotics similar to natural organisms are outlined to provide a perspective in this field. [Abstract copyright: © 2021.

Bio-inspired Antennal Tactile Sensing

Vision dominates perception research in robotics and biology, but for many animals, it is not the dominant sensory system. Indeed, arthropods often rely on sensory cues sampled via a pair of passive head-mounted antennae to achieve navigation and control. These mechanosensory structures support multimodal receptors—tactile, hygrometric, thermal, olfactory—enabling a wide range of sensorimotor behaviors. One model biological system, Periplaneta americana cockroach, performs a remarkably robust escape behavior by using its long, slender, flexible antennae to facilitate rapid closed-loop course control. The antenna is a passive, hyper-redundant kinematic linkage that acts as a distributed tactile sensory structure to mediate mechanical interactions with the environment at very high rates. This thesis demonstrates that the antennal mechanics are tuned to enable high-speed, high-bandwidth locomotor control even in total darkness. Despite the extraordinary success of antennal sensing in nature, there are few effective bio-inspired antennae. To incorporate similar antennal sensing capability in agile mobile robots, I developed a tunable bio-inspired modular robotic research antenna and experimentation platform. I also synthesized numerical models to approximate antenna mechanics under relevant boundary conditions, which I verified against my physical model. Both numerical simulations and physical experiments were conducted to isolate fundamental parameters that underly the stability and performance I observed in the biological model. Using a combination of numerical and robotic experiments, in concert with biological experiments conducted by my collaborators, I discovered that several behaviorally relevant characteristics of an antennae are predominantly governed by a combination of (1) the stiffness profile of the antenna and (2) the interaction of hairlike mechano-structures along the length of the antenna. I found that the “right” combination of these features improves the postural stability and the steady state spatial acuity of tactile interaction with the environment. Specifically, antennae with an exponentially decreasing stiffness profile accompanied by distally pointing anisotropic mechano-hairs are ideal for navigation tasks, and greatly facilitate stable high-speed wall following

Development of Multifunctional E-skin Sensors

Electronic skin (e-skin) is a hot topic due to its enormous potential for health monitoring, functional prosthesis, robotics, and human-machine-interfaces (HMI). For these applications, pressure and temperature sensors and energy harvesters are essential. Their performance may be tuned by their films micro-structuring, either through expensive and time-consuming photolithography techniques or low-cost yet low-tunability approaches. This PhD thesis aimed to introduce and explore a new micro-structuring technique to the field of e-skin – laser engraving – to produce multifunctional e-skin devices able to sense pressure and temperature while being self-powered. This technique was employed to produce moulds for soft lithography, in a low-cost, fast, and highly customizable way. Several parameters of the technique were studied to evaluate their impact in the performance of the devices, such as moulds materials, laser power and speed, and design variables. Amongst the piezoresistive sensors produced, sensors suitable for blood pressure wave detection at the wrist [sensitivity of – 3.2 kPa-1 below 119 Pa, limit of detection (LOD) of 15 Pa], general health monitoring (sensitivity of 4.5 kPa-1 below 10 kPa, relaxation time of 1.4 ms, micro-structured film thickness of only 133 µm), and robotics and functional prosthesis (sensitivity of – 6.4 × 10-3 kPa-1 between 1.2 kPa and 100 kPa, stable output over 27 500 cycles) were obtained. Temperature sensors with micro-cones were achieved with a temperature coefficient of resistance (TCR) of 2.3 %/°C. Energy harvesters based on micro-structured composites of polydimethylsiloxane (PDMS) and zinc tin oxide (ZnSnO3) nanowires (NWs; 120 V and 13 µA at > 100 N) or zinc oxide (ZnO) nanorods (NRs; 6 V at 2.3 N) were produced as well. The work described herein unveils the tremendous potential of the laser engraving technique to produce different e-skin devices with adjustable performance to suit distinct applications, with a high benefit/cost ratio

Theoretical Approaches in Non-Linear Dynamical Systems

From Preface: The 15th International Conference „Dynamical Systems - Theory and Applications” (DSTA 2019, 2-5 December, 2019, Lodz, Poland) gathered a numerous group of outstanding scientists and engineers who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without great effort of the staff of the Department of Automation, Biomechanics and Mechatronics of the Lodz University of Technology. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our event was attended by over 180 researchers from 35 countries all over the world, who decided to share the results of their research and experience in different fields related to dynamical systems. This year, the DSTA Conference Proceedings were split into two volumes entitled „Theoretical Approaches in Non-Linear Dynamical Systems” and „Applicable Solutions in Non-Linear Dynamical Systems”. In addition, DSTA 2019 resulted in three volumes of Springer Proceedings in Mathematics and Statistics entitled „Control and Stability of Dynamical Systems”, „Mathematical and Numerical Approaches in Dynamical Systems” and „Dynamical Systems in Mechatronics and Life Sciences”. Also, many outstanding papers will be recommended to special issues of renowned scientific journals.Cover design: Kaźmierczak, MarekTechnical editor: Kaźmierczak, Mare