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Researchers conventionally employ thermal imaging to monitor the health of animals, observe their habitat utilization, and track their activity patterns. These non-invasive methods can generate detailed images and offer valuable insights into behavior, movements, and environmental interactions. The aye-aye (Daubentonia madagascariensis), a rare and endangered lemur from Madagascar, possesses a uniquely slender third finger evolved for tapping surfaces at relatively high frequencies. The adaptation enables acoustic-based sensing to locate cavities with prey in trees to enhance their foraging abilities. The authors’ previous studies have demonstrated some descent simulating dynamic models of the aye-aye’s third digit referenced from limited data collected with monocular cameras, which can be challenging due to noisy and distorted images, impacting motion analysis adversely. In this proposed research, high-speed thermal cameras are employed to capture detailed finger position and orientation, providing a clearer understanding of the overall dynamic range. The improved biomimetic model aims to enhance tap-testing strategies in nondestructive evaluation for various inspection applications. 

The phenomenon of fish schooling - coordinated swimming of fish in polarized groups of specific spatial formations- is commonly observed in several species of fish. Fish schooling may even provide hydrodynamic advantages reducing the overall swimming cost of the group. To date, the role of hydrodynamics in coordinated swimming is not completely understood as it is difficult to separately study the role of hydrodynamic interaction from other forms of interaction between the fish. Here, we propose a statistical methodology based on information theoretic tools and flow velocity measurements, that can potentially tease out the hydrodynamic interaction pathways from visual and tactile ones. To avoid experimental confounds from bidirectional interactions and objectively understand cause-and-effect relationships, we design a robotic platform that mimics the behavior of two fish swimming in-line in a controlled setup inside a water channel. We examine the response of a flag to the fish-like unsteady wake generated by an actively pitching airfoil located upstream. We systematically quantify the passive hydrodynamic effect by studying the flapping motion of the flag located downstream of the airfoil in response to both periodic pitching and less predictable, random startling motion of the upstream airfoil. The study integrates experimental biomimetics with information theory to establish a deeper understanding of hydrodynamics in fish schooling. 

In this study, the implementation and performance of bipennate topology fluidic artificial muscle (FAM) bundles operating under varying boundary conditions is investigated and quantified experimentally. Soft actuators are of great interest to design engineers due to their inherent flexibility and potential to improve safety in human robot interactions. McKibben fluidic artificial muscles are soft actuators which exhibit high force to weight ratios and dynamically replicate natural muscle movement. These features, in addition to their low fabrication cost, set McKibben FAMs apart as attractive components for an actuation system. Previous studies have shown that there are significant advantages in force and contraction outputs when using bipennate topology FAM bundles as compared to the conventional parallel topology1 . In this study, we will experimentally explore the effects of two possible boundary conditions imposed on FAMs within a bipennate topology. One boundary condition is to pin the muscle fiber ends with fixed pin spacings while the other is biologically inspired and constrains the muscle fibers to remain in contact. This paper will outline design considerations for building a test platform for bipennate fluidic artificial muscle bundles with varying boundary conditions and present experimental results quantifying muscle displacement and force output. These metrics are used to analyze the tradespace between the two boundary conditions and the effect of varying pennation angles. 

Fluidic artificial muscles (FAMs) have emerged as a viable and popular robotic actuation technique due to their low cost, compliant nature, and high force-to-weight-ratio. In recent years, the concept of variable recruitment has emerged as a way to improve the efficiency of conventional hydraulic robotic systems. In variable recruitment, groups of FAMs are bundled together and divided into individual motor units. Each motor unit can be activated independently, which is similar to the sequential activation pattern observed in mammalian muscle. Previous researchers have performed quasistatic characterizations of variable recruitment bundles and some simple dynamic analyses and experiments with a simple 1- DOF robot arm. We have developed a linear hydraulic characterization testing platform that will allow for the testing of different types of variable recruitment bundle configurations under different loading conditions. The platform consists of a hydraulic drive cylinder that acts as a cyber-physical hardware-in-the-loop dynamic loading emulator and interfaces with the variable recruitment bundle. The desired inertial, damping and stiffness properties of the emulator can be prescribed and achieved through an admittance controller. In this paper, we test the ability of this admittance controller to emulate different inertial, stiffness, and damping properties in simulation and demonstrate that it can be used in hardware through a proof-of-concept experiment. The primary goal of this work is to develop a unique testing setup that will allow for the testing of different FAM configurations, controllers, or subsystems and their responses to different dynamic loads before they are implemented on more complex robotic systems. 

The aye-aye (Daubentonia madagascariensis) is a nocturnal lemur native to the island of Madagascar with a special thin middle finger. The aye-aye’s third digit (the slenderest one) has a remarkably specific adaptation, allowing it to perform tap-scanning (Finger tapping) to locate small cavities beneath tree bark and extract woodboring larvae from it. This finger, as an exceptional active acoustic actuator, makes an aye-aye’s biological system an attractive model for Nondestructive Evaluation (NDE) methods and robotic systems. Despite the important aspects of the topic in engineering sensory and NDE, little is known about the mechanism and movement of this unique finger. In this paper a simplified kinematic model was proposed to simulate the aye-aye’s middle finger motion. 

The aye-aye (Daubentonia madagascariensis) is the largest nocturnal primate in the world and possesses a number of distinct adaptations. The most striking feature of the aye-aye is perhaps its exceptional near-field auditory system adopted to support its unique tap-scanning process. This tap-scanning technique represents prominent evolutionary innovations in the animal’s biological auditory system. The current study provides an initial insight into proposing a biomimetic approach to determine how different morphological features might impact the ayeaye’s acoustic near-field auditory system. The experimental setup comprised a miniature piezoelectric hammer mounted on a Universal Robotics manipulator (UR5) (the integrated system provides a controlled tapping process) and a prepolarized capacitive measurement microphone (to capture the acoustic sound coming from each tap on the wooden sample). The pinnae of the aye-aye were 3D printed using a CT scan obtained from a carcass. The results show that the biomimetic setup can successfully be used for evaluating the near-field auditory system of aye-ayes. 

This paper investigates the effect of resistive forces that arise in compressed fluidic artificial muscles (FAMs) within a variable recruitment bundle. Much like our skeletal muscle organs that selectively recruit different number of motor fibers depending on the load demand, a variable recruitment FAM bundle adaptively activates the minimum number of motor units (MUs) to increase its overall efficiency. A variable recruitment bundle may operate in different recruitment states (RSs) during which only a subset of the FAMs within a bundle are activated. In such cases, a difference in strain occurs between active FAMs and inactive/low-pressure FAMs. This strain difference results in the compression of inactive/lowpressure FAMs causing them to exert a resistive force opposing the force output of active FAMs. This paper presents experimental measurements for a FAM for both tensile and compressive regions. The data is used to simulate the overall force-strain space of a variable recruitment bundle for when resistive force effects are neglected and when they are included. Counterintuitively, an initial decrease in bundle free strain is observed when a transition to a higher RS is made due to the presence of resistive forces. We call this phenomenon the free strain gradient reversal of a variable recruitment bundle. The paper is concluded with a discussion of the implications of this phenomenon.