  We present WEARDA, the open source WEARable sensor Data Acquisition software
package. WEARDA facilitates the acquisition of human activity data with
smartwatches and is primarily aimed at researchers who require transparency,
full control, and access to raw sensor data. It provides functionality to
simultaneously record raw data from four sensors -- tri-axis accelerometer,
tri-axis gyroscope, barometer, and GPS -- which should enable researchers to,
for example, estimate energy expenditure and mine movement trajectories. A
Samsung smartwatch running the Tizen OS was chosen because of 1) the required
functionalities of the smartwatch software API, 2) the availability of software
development tools and accessible documentation, 3) having the required sensors,
and 4) the requirements on case design for acceptance by the target user group.
WEARDA addresses five practical challenges concerning preparation, measurement,
logistics, privacy preservation, and reproducibility to ensure efficient and
errorless data collection. The software package was initially created for the
project "Dementia back at the heart of the community", and has been
successfully used in that context.
