Akitaka Imamura

Evaluation of quad ducted‐fan helicopter

Purpose – With the purpose of clearing up the risk to rotor blades, this paper develops a quad ducted‐fan helicopter using four ducted‐fans instead of four rotor blades in a quad rotor helicopter.Design/methodology/approach – Auto hovering test, auto cruise test, and altitude control simulations were conducted to estimate the flight performance of the quad ducted‐fan helicopter.Findings – Flight performance of the test quad ducted‐fan helicopter is almost same as a commercial quad rotor helicopter, and it succeeds to decrease the risk to the rotor blade. However, endurance is shorter than that of the quad rotor helicopter, because of the ducted‐fan characteristics.Research limitations/implications – The test quad ducted‐fan helicopter can fly for about four minutes with two packs of fourcell (16.8 V)‐2200 mAh Lipo batteries, and it needs about 3.3 times as much energy as quad rotor helicopter. The authors will improve the performance of quad ducted‐fan helicopter by aerodynamics analysis and design of duc...

Transmission performance of digital FM utilizing jointly Gaussian filter and Nyquist‐III filter for a premodulation filter

In this paper, we propose a new scheme of digital frequency modulation that jointly utilizes a Nyquist III filter and a Gaussian filter for a premodulation filter. In this scheme, the phase transition and the phase trajectory during the symbol interval are settled independently of each other by setting the parameters of the two filters, and it is thus possible to improve the transmission performance by controlling the parameters of these filters appropriately. Furthermore, this scheme has an additional merit of increasing the minimum signal-space distance d2min above 2.0, and it has the possibility of improving BER performance. When the bandwidth of the signal widens with the increase of d2min, it is possible to adjust the signal spectrum by utilizing the Gaussian filter. Thus, it is possible to obtain superior transmission performance by setting the parameters of the two filters appropriately and employing a suitable detection method. Furthermore, we show that the transmission performance of this scheme is as good as GMSK in an AWGN environment.

Attitude control of Quad Ducted-fan Helicopter

Recently, R/C single/multi rotor helicopter is used in fields of aerial photography and aerial investigation. But helicopter rotor blades are not covered, and the thrust is generated by high rotational speed. Thus R/C helicopter has a high risk of damage. In this study, we developed a new flying object using 4 ducted-fans instead of 4 rotor blades in quad rotor helicopter. We call this as Quad Ducted-fan Helicopter.

Extra Thruster for Quad Rotor Helicopter

As R/C airplane, Quad Rotor Helicopter (QRH)is tiltedits attitude to generate horizontal force component for moving direction. So attitude control is important. In the case of autonomous control, attitude control system tilts the airframe against to the disturbance such as wind. As a result, the attitude of flying QRH always slants. In this study, extra thruster rotors are mountedto keep the position and horizontal attitude of QRH. Extra thrusters are tilted to generate thrust against to the disturbance without airframe inclination. This system is constructed with two ducted fans which can slant by two axes. To oppose the crosswind, the thruster slants the ducted fan to leeward. Because the airframe is kept the horizontal, it is suitable for a precise measurement.