Aerodynamic parameters can be also inferred indirectly from the surface flow field around the wing using micro sensors [5,6]. The adoption of micro sensors has shown many technical and economical advantages compared with selleck chemicals FTY720 other conventional technologies. In the past two decades, several research groups have demonstrated micromachined flow sensors based on various principles, including thermal transfer [8,9], torque transfer, and pressure distribution.In this paper, a novel and practical approach, by which the flow fields around the wing are measured and used to deduce multiple aerodynamic parameters of the aircraft, is proposed and validated through wind tunnel experiments. We propose the use of a micro hot-film flow sensor array and a back-propagation (BP) neural network to deduce three aerodynamic parameters: air speed, angle of attack and angle of sideslip.
The sensors are tailor-developed on a flexible Inhibitors,Modulators,Libraries substrate and home fabricated. The hot film sensors are collocated on specific positions of the wing surface of a micro air vehicle, as illustrated in Figure 1. Two different arrangements: (1) hot film sensors 1, 2, 3, 4 and the Pitot tube; (2) hot film sensors I, II, III, IV and the Pitot tube, are proposed, tested and compared. The readings of the sensors are acquired and converted into digital signals as the inputs of the signal processor, whose outputs deduce the three aerodynamic parameters using a neural network-based data fusion technique. This methodology takes the merits of tiny sensing system, smooth and flexible traits, efficient data processing, and is thus especially suitable for applications on small UAVs and MAVs.
Figure 1.The collocation of hot film flow sensor array on a MAV.2.?Operating Principles of Sensor SystemThe developed hot film sensor system has the features of flexible film, smooth surface, small size, low weight, and ease of mounting on versatile surfaces. The thin-film design makes it possible for detecting surface flow or sheer Inhibitors,Modulators,Libraries stress while guaranteeing the least disturbance of the surface flow.2.1. Sensing PrinciplesThe hot film flow sensor utilizes a thermal metallic thin-film deposited on a flexible substrate that is mounted Inhibitors,Modulators,Libraries on the surface of the aircraft wing. The thermal element serves as both Joule heater and temperature sensor. Under a constant bias power and zero flow rates, the thermal element achieves a steady-state temperature, which means the heat transfer system reaches equilibrium.
If an external flow passes around the thermal element, the element experiences forced convective cooling. Accordingly, the temperature of the thermal element decreases, then the resistance of the element changes, and thus provides the information of the flow speed that governs the cooling rate.2.2. Inhibitors,Modulators,Libraries Sensor Structure and FabricationThe Anacetrapib micro hot film sensors used in this work were homemade [10]. LCL161? We used standard flexible PCB, i.e.