CAREER: The Musculoskeletal Biomechanics and Control of Limbless Locomotion

这个项目使用蛇的横向波动运动作为一个模型系统，来研究动物如何满足机械和控制需求并确定其优先顺序，特别是当这些需求受到限制或相互冲突时。尽管近20%的陆生脊椎动物使用了无肢体运动，但对它的研究仍然很少。在横向波动中，最普遍和最常见的无肢体运动模式是弯曲的波沿着身体向下传递，挤压环境中的结构(例如植物、岩石)，以推动蛇向前移动。横向波动带来了几个同时的挑战，包括满足机械动力需求，克服摩擦力，以及控制多个不断变化的接触点的力。这些要求可能会发生冲突；例如，从接触点产生最有效推进力的身体姿势可能会减少肌肉力量或功率输出。这个项目解决了蛇如何处理这种冲突，并通过在施加不同机械和控制要求的环境中测试动物，调查是否存在缓解或避免潜在权衡的机制。这项研究将为动物在运动过程中如何管理相互竞争的需求提供一般性的见解，特别是同时满足机械和控制需求的需求。了解无肢体运动也可以使受蛇启发的机器人受益，由于蛇在复杂、杂乱和受限的空间中移动的非凡能力，它是受生物启发的机器人的目标。该项目还与阿克伦大学野外站合作，通过利用一种基于定格动画的新型基于反馈的机器人编程，消除了学生学习如何编写代码的需要，在生物启发机器人方面向附近的高中提供了一个独特的推广机会。生物力学的一个核心挑战是了解肌肉的生理属性如何影响动物的运动，通常在专门的系统中进行测试，以最大化特定的度量(例如，功率或循环频率)。然而，大多数动物必须同时满足许多独立的机械和控制需求，并可以通过各种方式调节它们的动作来实现这一点。该项目使用蛇的陆地侧向波动作为模型系统，以了解动物如何满足这些需求，特别是当需求发生冲突时。地面无肢体运动以摩擦为主的机制对机械力和功率输出提出了直接的要求，这些要求将从仪表化的测试场地直接测量。蛇移动时中线弯曲的高度变化模式表明相应的肌肉应变轨迹也不同，这将通过荧光显微镜进行测量。多个推进反作用力取决于每个接触位置的局部姿势。如果肌肉的机械输出和控制都是由身体运动学决定的，那么这两个目标之间就有潜在的冲突：控制反作用力方向可能会影响肌肉的机械输出，反之亦然。这个项目涉及一个新颖的推广计划，使用活体动物演示和机器人学的组合，为学生提供生物启发的机器人设计体验，在其中他们观察蛇的运动，假设机制，并使用蛇启发的机器人测试这些机制。两名博士后研究员和一名研究生将为这项研究做出贡献，从而受益于跨学科培训和指导。该奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project uses locomotion by lateral undulation in snakes as a model system for investigating how animals meet and prioritize mechanical and control demands, especially when these demands are constrained or conflicting. Terrestrial limbless locomotion, despite being used by almost 20% of terrestrial vertebrates, remains understudied. In lateral undulation, the most widespread and common mode of limbless locomotion, waves of bending pass down the body, pressing against structures in the environment (e.g. plants, rocks) to propel the snake forward. Lateral undulation poses several simultaneous challenges, including meeting mechanical power demands, overcoming the force of friction, and controlling forces at multiple, constantly shifting contact points. These demands may conflict; for example, the body posture that generates the most effective propulsive force from a contact point might reduce muscular force or power output. This project addresses how snakes handle this conflict and investigates whether mechanisms exist to mitigate or avoid potential tradeoffs, by testing animals in environments that impose different mechanical and control demands. This research will provide general insights into how animals manage competing demands during locomotion, particularly the need to simultaneously meet mechanical and control demands. Understanding limbless locomotion can also benefit snake-inspired robots, a target of bio-inspired robotics due to the exceptional ability of snakes to move through complex, cluttered, and confined spaces. In partnership with the University of Akron field station, the project also provides a unique outreach opportunity in bio-inspired robotics to nearby high schools serving economically disadvantaged youth, by leveraging a new type of feedback-based robotic programming based on stop-motion animation to eliminate the need for students to learn how to write code.A central challenge of biomechanics is understanding how the physiological properties of muscle influence the movements of animals, often examined in specialized systems adapted to maximize a particular metric (e.g., power or cycle frequency). However, most animals must meet numerous independent mechanical and control demands simultaneously and can modulate their movements in a wide variety of ways to accomplish this. This project uses terrestrial lateral undulation in snakes as a model system to understand how animals meet these demands, particularly when the demands conflict. The friction-dominated mechanics of terrestrial limbless locomotion impose straightforward demands on mechanical force and power output, which will be directly measured from instrumented test arenas. The highly variable patterns of midline bending in snake locomotion suggest correspondingly variable muscle strain trajectories, which will be measured via fluoromicrometry. The multiple propulsive reaction forces depend upon local posture at each contact location. If both muscle mechanical output and control are determined by body kinematics, there is potential for conflict between these goals: control of reaction force orientation may compromise muscle mechanical outputs, and vice versa. This project involves a novel outreach program using a combination of live-animal demonstrations and robotics to provide students with a bio-inspired robotics design experience in which they observe a snake’s movements, hypothesize mechanisms, and test those mechanisms using snake-inspired robots. Two post-doctoral fellows and a graduate student will contribute to the research, thereby benefitting from interdisciplinary training and mentoring.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.