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Description

This project implements constraint and task space projection for OpenSim v4.0. The purpose is to design well documented, very simple and light-weighted API where the user can plan a movement in task space and perform simulations in a mixed dynamics manner. A mixed dynamics scheme is a combination of an inverse dynamics controller (equations of motion in task space) that feds a forward dynamics module.

The underlying task space controller supports task prioritization [1] and constraint modeling [2-3]. As the constraints are implicitly accounted in the inverse dynamics model this implementation is able to simulate accurately models that use constraints. Examples include: absolute (Cartesian) coordinates, closed kinematics chains and complex joint configurations (e.g. shoulder, knee) [4].

Examples can be found in the src/taskspace/examples folder. Results are stored in the data/results dir. All models are located in the data/ dir.

  • ExampleTaskBasedControl.cpp: a minimum working example of controlling a single body in task space

  • ExampleAbsoluteCoordinates.cpp: a two body model built using absolute coordinates and constraints for modeling the joint restrictions, with a position planning controller (task space) of the end-effector body; a selection matrix has been used to model under-actuation

  • ExampleClosedKinematicChain.cpp: three bodies are arranged in a closed kinematic chain topology and the planning is performed by defining the orientation of one of the bodies in task space

  • ExampleArm26.cpp: a musculoskeletal model that is controlled by multiple prioritized tasks where the muscle excitation that track the task goals are estimated using Task Space Computed Muscle Control [5]

References

[1] Sentis, L. (2007). Synthesis and Control of Whole-Body Behaviors in Humanoid Systems. Stanford University. Retrieved from http://dl.acm.org/citation.cfm?id=1354211

[2] De Sapio, V., & Park, J. (2010). Multitask Constrained Motion Control Using a Mass-Weighted Orthogonal Decomposition. Journal of Applied Mechanics, 77(4), 1–9. https://doi.org/10.1115/1.4000907

[3] Aghili, F. (2005). A unified approach for inverse and direct dynamics of constrained multibody systems based on linear projection operator: Applications to control and simulation. IEEE Transactions on Robotics, 21(5), 834–849. https://doi.org/10.1109/TRO.2005.851380

[4] Mistry, M., & Righetti, L. (2014). Operational Space Control of Constrained and Underactuated Systems. Robotics: Science and Systems VII.

Dependencies

OpenSim tested version

TODO

This project is a re-implementation of github so some features are still missing.

  • Task Space Dynamic Inverse Kinematics [5]

  • Implement test cases

Acknowledgment

[5] Dimitar Stanev and Konstantinos Moustakas, “Simulation of Constrained Musculoskeletal Systems in Task Space”, IEEE Transactions on Biomedical Engineering, vol. 65, no. 2, pp. 307-318, 2018, doi: 10.1109/TBME.2017.2764630

SimTK Project

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.