Contributor:
Computational model of human arm motions:
In this work, a computational model for human arm upper-limb motion generation considering the scapulohumeral rhythm of the shoulder is developed. The developed method is based on the theories from the neuroscience community regarding the Central Nervous System(CNS)’s governing rules for coordination of arm motions. These theories suggest that our CNS generates motions such that they require minimum muscular energy to perform. Existing computational models such as minimum jerk, minimum torque, etc, are based on the assumption that the shoulder joint does not move, and the origin of the reference frame is defined at the center of the glenohumeral (GH) joint. These computational methods are generally developed for simple point-to-point reaching movements with limited range of motion (RoM) which justifies the assumption of fixed shoulder center. However, most upper limb motions such as Activities of Daily Living (ADL) tasks include larger scale inward and outward reaching motions, during which the center of shoulder joint moves significantly.
A.
B.
A. Shoulder rhythm and the bones involved [ACEfitness.org]
B. Shoulder movement during upper-limb motions captured by motion capture system-washing opposite arm motion
We have developed a computational model capable of generating upper-limb ADL motions with high resemblance to human arm actual movements, as verified through comparison of the model outputs with the arm motions of healthy subjects captured via a MoCap system.
Human-like path generation in upper-limb exoskeletons:
Based on the proposed computational model, a new path generation algorithm for upper-limb exoskeletons is developed. The proposed motion planning method can be used in upper-limb exoskeletons with 3 Degrees of Freedom (DoF) in shoulder and 1 DoF in elbow which are capable of supporting the motion of the shoulder girdle by moving the center of shoulder joint.
Subjects performing upper-limb ADL motions to be captured by MoCap
End-effector level comparison of the developed path with the human arm motions and the minimum jerk model available in literature
Related articles:
- Soltani- Zarrin, A. Zeiaee, R. Langari, “Human-like Path Generation in Upper-limb Exoskeletons”, (under review).
- R. Soltani-Zarrin, A. Zeiaee, R. Langari, N. Robson, “Reference Path Generation for Upper-Arm Exoskeletons Considering Scapulohumeral Rhythms”, Proceedings of 2017 IEEE 15th International Conference on Rehabilitation Robotics, London.
- R. Soltani-Zarrin, A. Zeiaee, R. Langari, and R. Tafreshi, “A Computational Approach for Human-like Motion Generation in Upper Limb Exoskeletons Supporting Scapulohumeral Rhythms”, IEEE proceedings of 2017 International Symposium on Wearable & Rehabilitation Robotics (WeRob), Houston, 2017.