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Unformatted text preview: Simulation Lab #2: Dynamic Modeling and Simulation of Muscle-Tendon Actuators Professor B.J. Fregly Mechanics of the Human Locomotor System EML 5595 - Fall 2010 Laboratory Developers: Darryl Thelen, Silvia Blemker, Clay Anderson, Scott Delp Neuromuscular Biomechanics Lab, Stanford University Laboratory converted to OpenSim by Kate Saul Holzbaur, Wake Forest University I. Introduction The force producing properties of muscle are complex, highly nonlinear and can have substantial effects on movement (see McMahon 1984 for review). For simplicity, lumped-parameter dimensionless muscle models, capable of representing a range of muscles with different architectures, are commonly used in the dynamic simulation of movement (Zajac, 1989). In this simulation lab, we will review the differential equations that describe muscle activation and muscle-tendon contraction dynamics when using a Hill-type muscle model. You will use OpenSim to implement muscle-tendon models and conduct simulations to investigate how various model parameters affect the dynamic response of the actuators. The lab will conclude with a Virtual Muscle Tug-of-War in which you will design an optimal muscle and compete directly against others in the class – may the best muscle win! II. Objectives The purpose of this lab is to learn how to use and modify OpenSim models and code to model and simulate muscle-tendon dynamics contractions. By working through this lab, you will: • Become familiar with the differential equations describing muscle activation and muscle- tendon contraction dynamics. • Learn how to model and simulate dynamic musculo-tendon actions using OpenSim. • Become comfortable with modifying existing code that models muscle activation and mechanics. • Explore the effect of various model parameters and simulation conditions on the dynamic response of muscle. • Design your own “optimal” muscle-tendon actuator to compete in a virtual muscle tug of war. 2 III. Deliverables At the completion of this lab, you will need to turn in a written report and several OpenSim files from your modeling work. Please turn in: 1. A written report using the report template Simulate_Lab2_report.rtf. 2. The following files for the muscle you design (please e-mail to [email protected] and cc [email protected] ): a. YourLastName.osim including your muscle as muscle 1. b. YourLastName.sto and YourLastName.xml with your activation history. c. YourLastName.sto with your initial states. IV. Getting Started Download the following files from the course web site: Simulation_Lab2_report.rtf This file contains the template for the lab report. Simulation_Lab2.osim This file contains the template for a two-muscle tug-of-war with a block in the middle....
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- Spring '08
- muscle activation, muscle fiber length, T Zajac