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Abstract Latch-mediated spring actuation (LaMSA) systems leverage the interplay of springs and latches to rapidly accelerate a load. In biological systems, elastic energy is often distributed across multiple structures, resulting in forces applied from multiple springs. Here, we specifically examine dual spring force couples in torque reversal systems. A dual spring force couple applies forces from recoiling springs at two locations to generate torque. Torque reversal systems transition from spring loading to spring actuation through a change in torque direction. We develop a mathematical model of a dual spring force couple in a torque reversal system, where one spring is attached to the pivot point of the rigid body. During spring loading, this spring compresses to store elastic energy; during spring actuation, it recoils, driving pivot translation and contributing to rotation. We experimentally validate the model using a physical model. We then vary geometric parameters and the energy partition between the two springs to examine how these factors shape system dynamics. We show how variations in geometry and energy partition influence the rotational, translational, and coupling terms in the mathematical model. Finally, we demonstrate that the energetics of these systems must be carefully accounted for to accurately capture how potential energy is transformed into kinetic energy. We hypothesize that dual spring force couples in torque reversal systems may be prevalent in biological organisms, and that insights from this work can guide the design of spring-actuated mechanisms in robotics.
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Latch-mediated spring actuation (LaMSA): the power of integrated biomechanical systems
ABSTRACT Across the tree of life – from fungi to frogs – organisms wield small amounts of energy to generate fast and potent movements. These movements are propelled with elastic structures, and their loading and release are mediated by latch-like opposing forces. They comprise a class of elastic mechanisms termed latch-mediated spring actuation (LaMSA). Energy flow through LaMSA begins when an energy source loads elastic element(s) in the form of elastic potential energy. Opposing forces, often termed latches, prevent movement during loading of elastic potential energy. As the opposing forces are shifted, reduced or removed, elastic potential energy is transformed into kinetic energy of the spring and propelled mass. Removal of the opposing forces can occur instantaneously or throughout the movement, resulting in dramatically different outcomes for consistency and control of the movement. Structures used for storing elastic potential energy are often distinct from mechanisms that propel the mass: elastic potential energy is often distributed across surfaces and then transformed into localized mechanisms for propulsion. Organisms have evolved cascading springs and opposing forces not only to serially reduce the duration of energy release, but often to localize the most energy-dense events outside of the body to sustain use without self-destruction. Principles of energy flow and control in LaMSA biomechanical systems are emerging at a rapid pace. New discoveries are catalyzing remarkable growth of the historic field of elastic mechanisms through experimental biomechanics, synthesis of novel materials and structures, and high-performance robotics systems.
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- Award ID(s):
- 2019323
- PAR ID:
- 10434945
- Date Published:
- Journal Name:
- Journal of Experimental Biology
- Volume:
- 226
- Issue:
- Suppl_1
- ISSN:
- 0022-0949
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Ultrafast organisms exemplify how biological systems manipulate and control energy to generate spectacularly diverse movements. Across the tree of life, repeateduse, ultrafastmovements are driven by springs and controlled by opposing, latch-like forces. We focus on the biomechanical processes that sequentially reduce the duration of each energetic event to yield intense mechanical power density - often external to the organism to reduce self-damage.We leverage a new model system of young, transparent mantis shrimp (Stomatopoda) to quantify the timing and dynamics of muscle contraction, storage of elastic potential energy, latch engagement and release, and the levers and linkages that transform elastic potential to kinetic energy of their ultrafast strikes. We examine how the convergence of physical limits and inherent evolutionary integration of biomechanical structures yield generalizable features of energy storage and energy delivery, such that these mechanisms occur exclusively in small systems.While ultrafast organisms have historically been invisibly fast to science, today’s technology and new model systems have unveiled effective experimental approaches to quantifying energetic control and manipulation in these intriguing biomechanical systems.more » « less
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Synopsis We develop a model of latch-mediated spring actuated (LaMSA) systems relevant to comparative biomechanics and bioinspired design. The model contains five components: two motors (muscles), a spring, a latch, and a load mass. One motor loads the spring to store elastic energy and the second motor subsequently removes the latch, which releases the spring and causes movement of the load mass. We develop freely available software to accompany the model, which provides an extensible framework for simulating LaMSA systems. Output from the simulation includes information from the loading and release phases of motion, which can be used to calculate kinematic performance metrics that are important for biomechanical function. In parallel, we simulate a comparable, directly actuated system that uses the same motor and mass combinations as the LaMSA simulations. By rapidly iterating through biologically relevant input parameters to the model, simulated kinematic performance differences between LaMSA and directly actuated systems can be used to explore the evolutionary dynamics of biological LaMSA systems and uncover design principles for bioinspired LaMSA systems. As proof of principle of this concept, we compare a LaMSA simulation to a directly actuated simulation that includes either a Hill-type force-velocity trade-off or muscle activation dynamics, or both. For the biologically-relevant range of parameters explored, we find that the muscle force-velocity trade-off and muscle activation have similar effects on directly actuated performance. Including both of these dynamic muscle properties increases the accelerated mass range where a LaMSA system outperforms a directly actuated one.more » « less
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Abstract Ultrafast movements propelled by springs and released by latches are thought limited to energetic adjustments prior to movement, and seemingly cannot adjust once movement begins. Even so, across the tree of life, ultrafast organisms navigate dynamic environments and generate a range of movements, suggesting unrecognized capabilities for control. We develop a framework of control pathways leveraging the non-linear dynamics of spring-propelled, latch-released systems. We analytically model spring dynamics and develop reduced-parameter models of latch dynamics to quantify how they can be tuned internally or through changing external environments. Using Lagrangian mechanics, we test feedforward and feedback control implementation via spring and latch dynamics. We establish through empirically-informed modeling that ultrafast movement can be controllably varied during latch release and spring propulsion. A deeper understanding of the interconnection between multiple control pathways, and the tunability of each control pathway, in ultrafast biomechanical systems presented here has the potential to expand the capabilities of synthetic ultra-fast systems and provides a new framework to understand the behaviors of fast organisms subject to perturbations and environmental non-idealities.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1242/jeb.245262
