Design of multi-sensor for safety monitoring of heavy machinery

In this paper, a multi-sensor system in package (SiP) is designed for the safety monitoring of the heavy machinery. The multi-sensor is made up of several parts, including strain gauge array, acceleration sensor, temperature sensor, and a pair of ultrasonic detector and actuator. Strain gauge array in a certain pattern is used to monitor the strain and stress level at some critical positions of the heavy machinery. At the same time, the acceleration sensor is used to examine the status of the vibration and monitors possible events such as impact or shock, providing the needed data for loading monitoring and liability, while the ultrasonic detector/actuator is adapted to detect the crack formed within the parts of the heavy machinery for those easy-to-fail parts. All parts of the system are integrated on a special flexible substrate with micro vias, through which the signal transmission and electrical interconnection among all devices are achieved. Besides, the total system is fixed at the heavy machinery through the flexible substrate, so that a real-time safety monitoring for the important parts of the heavy machinery can be accomplished, even when the heavy machinery is at work. The system is powered by two methods. For the lower power devices like the strain gauges, some materials in the system with the property of piezoelectricity can supply the energy for them, while for the larger ones such as the ultrasonic detectors, wire is needed. Apart from those listed above, wireless transmission devices are also included in the system so that the signal can be sent and received. The system prototype has been made and it is expected that the module will be integrated into the internet of things, a service network good for maintaining and servicing of engineering product systems in the field.