KNES 300 Lecture Notes - Lecture 9: Time Series, Sneakers, Usain Bolt
22 Feb 2017
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Average and instantaneous equations: also apply for angular kinematics. Constant acceleration equations: also apply for angular kinematics, need to have constant angular acceleration. Numerical differentiation and integration: also apply for angular kinematics. 2 i i a d f t 2. Measured data: linear positions of markers on the body, generally not meaningful. Sagittal plane analysis: (x,y) positions of markers on joint centers, define sagittal axes of rotation. Define a linked segment model: stick figure, rigid (non-deformable) body segments, connect adjacent joints. First step: calculate segment angles: remember: relative to right horizontal. Second step: calculate joint angles: difference between two segment angles (in 2d, considerably more complicated in 3d. Segment qthigh - qtrunk qshank - qthigh qfoot qshank /2. Convenient 2d standard: vertical upright standing, meaning of (cid:498)zero(cid:499) joint angles, normalize to standing posture, not always a great idea, controversial for 3d. Preceding analysis was for a single frame: repeat for every frame, result: time series of joint and segment angles.
