A Tunable, Simplified Model for Biological Latch Mediated Spring Actuated Systems

Abstract

We develop a model of latch-mediated spring actuated (LaMSA) systems relevant to comparative biomechanics. 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 open-source software to accompany the model, which provides an extensible framework for simulating biological 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 biological function. By rapidly iterating through biologically relevant input parameters to the model, simulated changes in kinematic performance can be used to explore the evolutionary dynamics of biological LaMSA systems.SIGNIFICANCEIn this work, we provide an example of a simple and extensible modeling framework that is grounded in physical principles. This framework enables both the rapid testing of ideas and the flexibility of tuning the model to a specific biological system. The model and open-source software can be used to explore questions in comparative biomechanics related to spring actuated movements.

The ultrafast snap of a finger is mediated by skin friction

“…In previous LaMSA systems, the latch geometry has been assumed to be sufficient in preventing load release [16,30,32]. This assumption has been justified by limiting latch and load motion to 1-D motion and by positioning the latch and load during force loading in such a way that there would be no horizontal force vectors acting on the latch as a result of the load.…”

“…We will also use this model to explore the general features of the energetics involved in a friction-mediated LaMSA model. The simplified model we develop builds off our previously published model of spring-driven movements described in detail in [16,30]. This model uses a loading motor to compress a spring against a latch, storing an amount of elastic energy determined by both the force characteristics of the loading motor and the material and geometric properties of the spring.…”

The ultrafast snap of a finger is mediated by skin friction

“…The simplified model we develop builds off our previously published model of spring-driven movements described in detail in [15,31]. This model uses a loading motor to compress a spring against a latch, storing an amount of elastic energy determined by both the force characteristics of the loading motor and the material and geometric properties of the spring.…”

“…In previous LaMSA systems, the latch geometry has been assumed to be sufficient in preventing load release [21,31,33]. This assumption has been justified by limiting latch and load motion to 1-D motion and by positioning the latch and load during force loading in such a way that there would be no horizontal force vectors acting on the latch as a result of the load.…”