REEV SENSE is a medical device, with pending FDA and CE certifications in class 1. It is a connected gait tracker set primarily on the leg or foot, and eventually on lower limb locations. It contains an accelerometer, a certified standard battery and motion analysis algorithms that will rapidly compute easy-to-use walking analyses accessible to healthcare professionals on a mobile app. Standard gait biomarkers such as velocity, stride length, or stance and swing times will be computed. However, REEV has also developed a new biomarker, the knee position predictor (KPP), which will provide a more accurate quantification of each individual gait profile. The present REEV SENSE study is the first to test subjects with a pathological context, i.e. with post-stroke ambulation deficit. Performance of REEV SENSE has already been established in healthy volunteers in comparison to the reference motion capture system, indicating good technical and metrological performance. The study will take place at the MIT Center for Clinical and Translational Research (CCTR), a reference center with a fully equipped gait lab. Each participating volunteer will be equipped with REEV SENSE and the reference motion capture system. The participant will be asked to walk at a comfortable self selected pace for about 15 minutes back and forth along a 10m walkway. He or she may rest at any time during the walking session. REEV SENSE and motion capture data will be recorded automatically and simultaneously during the same walking session.