It started with a report based on How Much Sleep Do Fitbit Users Really Get? A New Study Finds Out by Danielle Kosecki. That lead to research about Wrist actigraphy. And then Amazon had a sale on the Letscom Fitness Tracker. Actigraphy has been around since the 50’s. The cell phone sensor revolution has put it into the realm of every day, every man use.
A fitness tracker is a stripped down cell phone worn on the wrist. Bluetooth is the usual communications method used to pass data to a cell phone app. The sensors are an accelerometer and a pulse meter. A display, battery, and an SOC round out the package. On the Letscom, the accelerometer is Kionix KX022 and the SOC is a Nordic nRF51822. From a modern hardware perspective, there isn’t much there. It’s the software and the social and cultural aspects that make the product.
First up on software is the device firmware. It needs to track activity and control and present its measures in a reasonable fashion. It also usually provides wrist watch functions and some Smartphone coordination for alarms and messaging.
The second level is the phone app. Letscom uses VeryFitPro (Google Play). Google has been involved in this area and has Google Fit for an API and some other standardization for sharing on social networks and interactions between devices. It is this sharing that Fitbit may be using with cloud storage to collect data from its users that makes data mining research feasible and useful. The app provides extended data storage and analysis for the fitness tracker as well as serving as a larger display and control and configuration device.
Third level software is where the fun starts. That is where you tap into the data flow for doing your own presentation and analysis. This is not directly supported but there are several websites out there about methods to get fitness tracker data to your own database.
The Letscom costs quite a bit less than the market leading FitBit. It seems well built and both the firmware and the app are well rated and quite usable. Even at the normal $30 Amazon price, it offers a lot for the cost, especially as a starting point on how the development of modern sensors can be used for new products and in reducing costs of medical studies or other quality of life interests.