  With the rapid development of the internet of things (IoT) and artificial
intelligence (AI) technologies, human activity recognition (HAR) has been
applied in a variety of domains such as security and surveillance, human-robot
interaction, and entertainment. Even though a number of surveys and review
papers have been published, there is a lack of HAR overview paper focusing on
healthcare applications that use wearable sensors. Therefore, we fill in the
gap by presenting this overview paper. In particular, we present our emerging
HAR projects for healthcare: identification of human activities for intensive
care unit (ICU) patients and Duchenne muscular dystrophy (DMD) patients. Our
HAR systems include hardware design to collect sensor data from ICU patients
and DMD patients and accurate AI models to recognize patients' activities. This
overview paper covers considerations and settings for building a HAR healthcare
system, including sensor factors, AI model comparison, and system challenges.
