Knee up: An exercise game for standing knee raises by motion capture using RGB-D data

In this work, Knee Up exergame that promotes knee health via standing knee raises exercise is designed and implemented. It allows users to exercise at home and perform the exercise in a gaming environment. By motion capture using RGB-D data, estimated positions of the user's skeletal joints are acquired and processed in real-time. For the game, 3D virtual environments have been created with gamifcation elements so that users can enjoy more interactive and engaging exercise sessions. The game facilitates to evaluate the quality of performed standing knee raises exercises through a rule-based recognition algorithm and, in return, to provide timely feedback. A formal user study was conducted in order to evaluate the usability and gamification aspects of Knee Up. Study results demonstrate that Knee Up is generally well-received in terms of usability, engagement, ease of learning to play, and exercise sustainability; and validate that the rule-based recognition algorithm works satisfactorily well.