英文摘要 | The small-scale unmanned helicopter, an aerial robot developed in recent years, has high flexibilities and agilities such as vertical taking off and landing, hovering, cruising in arbitrary directions, pirouetting etc. Having such unique merits, the small-scale unmanned helicopter possesses great value and significant potentials in both military and civil applications. Researches manifest that the small-scale unmanned helicopter is a typical multi-input multi-output (MIMO) and under-actuated system, which is inherently unstable, highly nonlinear, strongly coupled, and together with its mode and dynamics varied in full flight envelope. Considering the complicated dynamic characteristics of the small-scale unmanned helicopter system, the development of its flight control system (FCS) is difficult, and therefore the key to achieve its autonomous flight.. In this thesis, a study is made on the characteristics of autonomous flight of small-scale unmanned helicopters, which involves mathematical modeling, model identification, robust flight control system design and optimization, etc. The main contributions of this thesis include following issues: 1. A study is made on the helicopter's flight theory and aerodynamic theory. On the basis of the theory studied and the first-principle modeling method, we build the mathematical models, including a nonlinear one for simulation, and a linear one for controller design, for the small-scale unmanned helicopter. With the analysis of the coupling characteristics of the small-scale helicopter, we build models suitable for the experiment of system identification. These models include the lateral and longitudinal coupling model, yaw model, and heave model. 2. The principle and identification procedure of prediction error method (PEM) is studied. Using the PEM identification method, we propose an approach to identify an MIMO coupling model for lateral and longitudinal channel, and SISO models for yaw channel and heave channel, respectively. With flight experiments, we obtain the parameters of such models of a small-scale unmanned helicopter. 3. Based on the H∞ loop shaping design procedure (LSDP), a robust controller design method is proposed for the flight control of small-scale unmanned helicopters. With this method, we design the controllers for the control of pitch/roll attitude, yaw angular rate, heave velocity, respectively. The comparison study from simulation with PID controllers and the controllers obtained wi... |
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