Dual-arm dynamic motion simulation and prediction of joint constraint loads using optimization

Joo H. Kim, Karim Abdel-Malek, Jingzhou Yang, Kyle J. Nebel

Research output: Contribution to journalConference articlepeer-review


Our previous formulation for optimization-based dynamic motion simulation of a serial-link human upper body (from waist to right hand) is extended to predict the motion of a tree-structured human model that includes the torso, right arm, and left arm, with various applied external loads. The dynamics of tree-structured systems is formulated and implemented. The equations of motion for the tree structures must be derived carefully when dealing with the connection link. The optimum solution results show realistic dual-arm human motions and the required joint actuator torques. In the second part of this paper, a new method is introduced in which the constraint forces and moments at the joints are calculated along with the motion and muscle-induced actuator torques. A set of fictitious joints are modeled in addition to the real joints. Then the constraint forces/moments for the fictitious joints are obtained from an extension of our optimization method together with zero-displacement constraints. Our formulation provides a multi-body dynamics method that does not require numerical integration and results in accurate joint constraint loads.

Original languageEnglish
JournalSAE Technical Papers
StatePublished - 2007
EventDigital Human Modeling for Design and Engineering Conference and Exhibition - Seattle, WA, United States
Duration: Jun 12 2007Jun 14 2007


  • Tree structure
  • differential-algebraic equations of motion
  • fictitious joints
  • joint constraint forces and moments
  • multi-body dynamics
  • optimization


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