Modellbasierte Erfassung der dreidimensionalen Kinetik der Bewegungen der oberen Extremitäten

Abstract

Movements in everyday life are linked with joint loads. Overloads and non-physiological stresses can lead to the pathological changes that can cause pain or even movement disability. In order to determine these loads, not only movement kinematics, but also dynamics should be analyzed. This thesis describes the development of a methodology for determining the net joint forces and moments for free upper extremity movement. Therefore, the body segment parameters (BSP), the joint angles in anatomical axes and the external loads are needed as input. Only inter- and intra-individual reproducible input data allow a relevant medical conclusion. In this thesis, a robot-based methodology has been developed which increases the intra- and inter-individual reproducibility of joint angles by pre-defining the subject’s/patient’s movement path. A 6 dof force/torque sensor has been attached to the roboter’s end effector to measure external forces and torques during free upper extremity movements. Subject would hold a handle on the end effector and move the arm in pre-defined motion path while external loads have been measured. A visual feedback about force has been developed to visualize the actual and target force to the subject. In this way, the inter- and intra-individual differences in external force can be reduced. These data were used as input for inverse dynamics model that was developed to calculate net joint forces and torques in anatomical axes for free upper extremity movement. For validation of the measurement procedure developed in this thesis, model-based simulation of a physiological movement and of a movement with inner rotation of the shoulder joint has been carried out. The experimental measurements on healthy subjects and patients with inner rotation of the shoulder have been made. In this way, the physiological patterns for net joint forces and moments have been determined and were used as a basis for detection of non-physiological loads. Overall, it has been shown, that the developed methodology is suitable for determination of joint loads in free upper extremity movement. It can provide the important information to physicians and therapists to support the surgical planning and outcome evaluation processes for interventions on musculoskeletal system of upper extremities