Researchers from Spain have recently developed a safety system that uses Bluetooth Low Energy (BLE) to ensure the correct use of Personal Protection Equipment (PPE) on construction sites. This innovative system is not only robust and reliable but also easily adaptable to various dangerous machines.
The system is built on RSSI (Received Signal Strength Indicator) information transmitted by BLE devices arranged in a particular rig combined with a Bayesian distance estimator. The aim is not merely to signal risky situations caused by the misuse of PPE but to intervene swiftly and robustly to eliminate the safety risk.
The researchers have built upon previous results on the statistically sound measurement of distances and closeness in construction sites. By collocating several BLE transmitters near orthogonally, they have managed to reduce interferences while avoiding the cost of more advanced technologies.
The practical contributions of this research include the design of the system, a working prototype and a thorough statistical analysis for finding the optimal parameters for both the software and the equipment. The research shows that using several orthogonally collocated BLE transmitters improves robustness and overall performance without requiring more complex and costly equipment.
The improvements are most significant as the number of transmitters increases. Using a diversity of devices is better when these devices are noisy and it also enhances the robustness of the solution. An arrangement of orthogonal BLE beacons allows for an increased rate of advertising messages, and an extended Kalman filter plus a discrete filter can benefit from that increased flow of data, providing a simple and efficient approximation to the problem of safety estimation.
The use of an additional beacon to notify the correct use of the PPE, implemented inside a wearable microcontroller, is a very flexible solution. It allows for different local implementations using various sensors and measurements without the need to modify the RSSI-only method in the receiver, and with any number of users. The system can be easily integrated into a wide variety of dangerous machines and tools such as angle grinders, concrete mixers and pneumatic drills.