• • • SAFETY IN ENGINEERING • • •
obstacles between the device and the central system. A single gateway can cover a large area of up to 10 km, depending on the environment. The main disadvantage of LoRa is its relatively slow data rate, so applications have to be adapted to minimise data transfer.
Smart Geofencing
Another key type of application where wireless technology can make a contribution to worker safety is via smart geofencing. In such a solution, precise distance measurement can be used to ensure that workers are separated from dangerous machines or zones by the appropriate distance. In the case a worker is too close, an alert can be issued to the worker, or the machine can be shut down, or in the case of moving vehicles, they could be stopped if they are too close to a worker.
Ultra-wide Band is a good technology for such cases, and it provides precise distance measurement, and can so quickly, so it is capable of responding to a vehicle moving at moderate speed – for example a fork lift truck or a mechanical digger.
Such technology could also be used to help enforce social distancing, should we find ourselves in another pandemic situation.
Issues with wireless technologies in body worn devices
Building solutions using wireless technology for wearable devices does introduce some significant challenges. Depending on the frequencies in use, the close proximity of the human body can make a major impact on radio performance and, therefore, the effectiveness of the solution. It also can introduce additional regulatory challenges, which vary by region. FCC regulations in the United States are particularly demanding, for example.
It is, therefore, important to design the device carefully, in order to firstly ensure there are no unnecessary RF losses, and then to place the antennas carefully to minimise absorption by the human body. There can be a difficult trade-off between the ergonomic requirements of a small unobtrusive device, and the performance requirements of the solution. A key task before designing the solution is, therefore, to determine the requirements for RF performance in terms of data rate, range, link budget necessary and other factors.
Other approaches could be to design a solution into a hard hat, or somebody worn
garment such as vest, where the wearable device can be more easily separated from close proximity to the body without impeding the user.
As is clear from this overview of different applications and solutions, many of which are available as real-world products, there are many ways in which wearable technology can assist in keeping workers safe. However, there are many different wireless technologies that can be deployed, and deciding which one to choose is a quite complex task. Factors to consider are the ergonomic demands for the device, the type of environment in which it will be deployed and the technical infrastructure that may or may not be available. Many solutions will require multiple radio technologies to support the full product lifecycle, meaning initial commissioning, active use, update and maintenance and system management. And of course, any technical solution has to be as robust as possible to the ‘human factor’, meaning they have to be comfortable to wear and easy to use. Smart PPE is not going to be cheap or easy, but human wellbeing and safety has to be a priority for the future.
electricalengineeringmagazine.co.uk
ELECTRICAL ENGINEERING • JULY/AUGUST 2025 31
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