Design And Implementation Of Wireless Passive Sensor Network For Vehicle

Vehicle overhaul is an important measure to ensure the safety.Wireless sensor networks have the characteristics of low power consumption,high reliability and flexibility,which make them widely used in the field of vehicle health monitoring.However,most current wireless sensor network nodes completely depend on the external battery for power supply,which results in problems of limited battery energy storage,high cost of battery replacement,and environmental pollution caused by used batteries.Designing passive wireless sensor network nodes using energy harvesting techniques is an effective solution.There are some problems that most of the existing passive wireless sensor network nodes face,such as the slow speed of energy collection,the low rate of energy conversion and small output of the power.Therefore,the node energy is limited and unstable.In addition,the wide distribution of the nodes makes the energy consumption of networking between nodes by multi-hop routing increase and aggravates the unbalanced distribution of energy consumption.Some nodes might be overloaded and even cause the paralysis of network.It will have impacts on the transmission efficiency and stability of the network.For these problems,this theses designed a passive wireless sensor network node based on vibration energy harvesting device for vehicles.And a distributed low power network was proposed for passive wireless sensor nodes.Vibration energy is widely distributed and stable under the scenarios of vehicle traffic.Therefore,this theses adopts the electromagnetic vibration energy harvester and designed an asynchronous energy harvesting circuit that can support the radio function.It reduces the influence of the vibration frequency and other factors on the performance of the equipment and improves the energy collection rate.It can provide stable power supply for sensor node.In the aspect of communication scheme design,firstly,this theses proposed a network architecture based on independent distributed subnets for the problems of widespread nodes and difficult networking.Subnet with a simple star topology achieves a unified management of internal resources and improves the overall energy efficiency of the system.Secondly,aiming at the problem of limited node energy,this theses adopted TDMA transmission protocol which is higher controllability and better in real-time performance.Thirdly,this theses designed the network superframe,time slot scheduling and data message for the wireless passive sensor network for vehicle.Moreover,it reduces the consumption by setting different start frequencies for the node tasks.At the same time,aiming at the problem of random start-up time and unbalanced energy consumption of nodes,a dynamic node selection algorithm is designed.Finally,the theses tests the function of wireless passive sensor nodes based on vibration energy collection.Through the networking test of nodes,the basic functions of vehicle-mounted wireless passive sensor networks are verified.The experimental results show that the wireless passive sensor network for vehicle designed in this theses achieves the design goal.