A Miniature Animal-Computer Interface for Use with Free-Flying Moths

Although the neurophysiological basis of insect flight control has been studied extensively and successfully in animals attached to rigid tethers, these conditions disrupt the natural feedback between the subject's intentions, sensory input, and motor output. Understanding how individual control algorithms are integrated at a behavioral level requires acquisition and modification of biopotentials in completely untethered, free-flying animals. Herein, I present and test a miniaturized animal-computer interface for use with freely-flying Manduca sexta hawkmoths. This device is capable of simultaneously acquiring two independent biopotential signals, applying electrical neuromuscular stimulation, and correlating collected and applied signals with behavioral data from high-speed videography. Application of this device may offer substantial insight into how insects fly and, by replicating these mechanisms, facilitate wider application of micro air vehicles through improved flight efficiency, stability, and maneuverability

Neuromuscular and biomechanical compensation for wing asymmetry in insect hovering flight

SUMMARY Wing damage is common in flying insects and has been studied using a variety of approaches to assess its biomechanical and fitness consequences. Results of these studies range from strong to nil effect among the variety of species, fitness measurements and damage modes studied, suggesting that not all damage modes are equal and that insects may be well adapted to compensate for some types of damage. Here, we examine the biomechanical and neuromuscular means by which flying insects compensate for asymmetric wing damage, which is expected to produce asymmetric flight forces and torques and thus destabilize the animal in addition to reducing its total wing size. We measured the kinematic and neuromuscular responses of hawkmoths (Manduca sexta) hovering in free flight with asymmetrically damaged wings via high-speed videography and extracellular neuromuscular activity recordings. The animals responded to asymmetric wing damage with asymmetric changes to wing stroke amplitude sufficient to restore symmetry in lift production. These asymmetries in stroke amplitude were significantly correlated with bilateral asymmetries in the timing of activation of the dorsal ventral muscle among and within trials. Correspondingly, the magnitude of wing asymmetry was significantly, although non-linearly, correlated with the magnitude of the neuromuscular response among individuals. The strongly non-linear nature of the relationship suggests that active neural compensation for asymmetric wing damage may only be necessary above a threshold (>12% asymmetry in wing second moment of area in this case) below which passive mechanisms may be adequate to maintain flight stability

Neuromuscular control of free-flight yaw turns in the hawkmoth Manduca sexta

SUMMARY The biomechanical properties of an animal’s locomotor structures profoundly influence the relationship between neuromuscular inputs and body movements. In particular, passive stability properties are of interest as they may offer a non-neural mechanism for simplifying control of locomotion. Here, we hypothesized that a passive stability property of animal flight, flapping counter-torque (FCT), allows hawkmoths to control planar yaw turns in a damping-dominated framework that makes rotational velocity directly proportional to neuromuscular activity. This contrasts with a more familiar inertia-dominated framework where acceleration is proportional to force and neuromuscular activity. To test our hypothesis, we collected flight muscle activation timing, yaw velocity and acceleration data from freely flying hawkmoths engaged in planar yaw turns. Statistical models built from these data then allowed us to infer the degree to which the moths inhabit either damping- or inertia-dominated control domains. Contrary to our hypothesis, a combined model corresponding to inertia-dominated control of yaw but including substantial damping effects best linked the neuromuscular and kinematic data. This result shows the importance of including passive stability properties in neuromechanical models of flight control and reveals possible trade-offs between manoeuvrability and stability derived from damping

Biomechanical Multifunctionality in the Ghost Crab, Ocypode quadrata

Bioinspired robotics has experienced unprecedented advancements. Robots can now run, swim and fly. Despite these advancements, the animals that inspired these robots remain substantially more versatile, using the same set of multifunctional appendages to perform many different tasks or behaviors. Understanding how biomechanics and behavior contribute to these capabilities will offer new insight into the science of animal movement and potentially inspire new multifunctional robotic technologies. Here, the ghost crab, Ocypode quadrata, was examined. These crabs, which are among the fastest land invertebrates, use relatively simple, unspecialized appendages to run, climb, burrow and dexterously capture prey. This dissertation focuses on ghost crabs’ burrowing and climbing behaviors. Both of these involve complex behavioral suites that involve the walking legs, the chelae and the body. Crabs demonstrated specialized postures, locomotion in confined spaces and goal-directed manipulation of both the environment and themselves. Both burrowing and climbing strategies involved compensatory strategies that allowed the crabs to maintain performance across a wide range of environmental conditions. Crabs do not rely on specialized appendage features but rather on the ability to use all appendages together. The findings presented in this dissertation represent new insight into the biomechanics of multifunctionality and offer inspiration for new bio-inspired robots with multi-use parts that permit, not simply obstacle negotiation, but also modification of the environment

Biomechanical Multifunctionality in the Ghost Crab, Ocypode quadrata

Bioinspired robotics has experienced unprecedented advancements. Robots can now run, swim and fly. Despite these advancements, the animals that inspired these robots remain substantially more versatile, using the same set of multifunctional appendages to perform many different tasks or behaviors. Understanding how biomechanics and behavior contribute to these capabilities will offer new insight into the science of animal movement and potentially inspire new multifunctional robotic technologies. Here, the ghost crab, Ocypode quadrata, was examined. These crabs, which are among the fastest land invertebrates, use relatively simple, unspecialized appendages to run, climb, burrow and dexterously capture prey. This dissertation focuses on ghost crabs’ burrowing and climbing behaviors. Both of these involve complex behavioral suites that involve the walking legs, the chelae and the body. Crabs demonstrated specialized postures, locomotion in confined spaces and goal-directed manipulation of both the environment and themselves. Both burrowing and climbing strategies involved compensatory strategies that allowed the crabs to maintain performance across a wide range of environmental conditions. Crabs do not rely on specialized appendage features but rather on the ability to use all appendages together. The findings presented in this dissertation represent new insight into the biomechanics of multifunctionality and offer inspiration for new bio-inspired robots with multi-use parts that permit, not simply obstacle negotiation, but also modification of the environment

Biomechanical Multifunctionality in the Ghost Crab, Ocypode quadrata

Bioinspired robotics has experienced unprecedented advancements. Robots can now run, swim and fly. Despite these advancements, the animals that inspired these robots remain substantially more versatile, using the same set of multifunctional appendages to perform many different tasks or behaviors. Understanding how biomechanics and behavior contribute to these capabilities will offer new insight into the science of animal movement and potentially inspire new multifunctional robotic technologies. Here, the ghost crab, Ocypode quadrata, was examined. These crabs, which are among the fastest land invertebrates, use relatively simple, unspecialized appendages to run, climb, burrow and dexterously capture prey. This dissertation focuses on ghost crabs’ burrowing and climbing behaviors. Both of these involve complex behavioral suites that involve the walking legs, the chelae and the body. Crabs demonstrated specialized postures, locomotion in confined spaces and goal-directed manipulation of both the environment and themselves. Both burrowing and climbing strategies involved compensatory strategies that allowed the crabs to maintain performance across a wide range of environmental conditions. Crabs do not rely on specialized appendage features but rather on the ability to use all appendages together. The findings presented in this dissertation represent new insight into the biomechanics of multifunctionality and offer inspiration for new bio-inspired robots with multi-use parts that permit, not simply obstacle negotiation, but also modification of the environment

Physical Health Problems and Environmental Challenges Influence Balancing Behaviour in Laying Hens.

With rising public concern for animal welfare, many major food chains and restaurants are changing their policies, strictly buying their eggs from non-cage producers. However, with the additional space in these cage-free systems to perform natural behaviours and movements comes the risk of injury. We evaluated the ability to maintain balance in adult laying hens with health problems (footpad dermatitis, keel damage, poor wing feather cover; n = 15) using a series of environmental challenges and compared such abilities with those of healthy birds (n = 5). Environmental challenges consisted of visual and spatial constraints, created using a head mask, perch obstacles, and static and swaying perch states. We hypothesized that perch movement, environmental challenges, and diminished physical health would negatively impact perching performance demonstrated as balance (as measured by time spent on perch and by number of falls of the perch) and would require more exaggerated correctional movements. We measured perching stability whereby each bird underwent eight 30-second trials on a static and swaying perch: with and without disrupted vision (head mask), with and without space limitations (obstacles) and combinations thereof. Video recordings (600 Hz) and a three-axis accelerometer/gyroscope (100 Hz) were used to measure the number of jumps/falls, latencies to leave the perch, as well as magnitude and direction of both linear and rotational balance-correcting movements. Laying hens with and without physical health problems, in both challenged and unchallenged environments, managed to perch and remain off the ground. We attribute this capacity to our training of the birds. Environmental challenges and physical state had an effect on the use of accelerations and rotations to stabilize themselves on a perch. Birds with physical health problems performed a higher frequency of rotational corrections to keep the body centered over the perch, whereas, for both health categories, environmental challenges required more intense and variable movement corrections. Collectively, these results provide novel empirical support for the effectiveness of training, and highlight that overcrowding, visual constraints, and poor physical health all reduce perching performance