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Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Urban air mobility (UAM) represents a promising solution for alleviating contemporary ground traffic congestion challenges. Consequently, a comprehensive analysis of power system operational characteristics within typical flight mission profiles for flying cars is of utmost importance. Due to constraints associated with battery energy density and the limited range of all-electric flying cars, the adoption of an oil-electric hybrid power system for flying cars is a more pragmatic choice. An overview of pertinent research concerning the operational performance of hybrid systems in vertical takeoff and landing ( VTOL) vehicles was provided. Utilizing MATLAB Simulink, a hybrid power coordination method was proposed that accounted for both operational modes. Distinct operational modes were predefined in accordance with actual operational conditions, encompassing vertical take-off and landing as well as level flight scenarios. Building upon this foundation, the coordination of the battery was explored, serving as the primary power source, to regulate power flow and enhance the efficiency of the range extender. The DC bus voltage was subject to regulation through a DC/ DC converter. To promote the overall longevity of the battery pack, power sharing mechanisms were introduced during both charging and discharging phases. Simulation results underscore the proficient control of the DC bus voltage, and power distribution between the range extender and the battery aligns with the predetermined design parameters. [ABSTRACT FROM AUTHOR]

In order to extend the flight time of flying cars and enable them to function seamlessly in both airborne and land-based modes, designing and selecting wings was focused on for flying cars based on the lift formula. Subsequently, folding and retrieval mechanisms for the wings were designed, and a kinematic model of the wing folding and retrieval mechanisms was established using the complex vector method. MATLAB was used to analyze and calculate the angular displacement, angular velocity, and angular acceleration of critical components within the mechanism, while Adams was utilized for motion simulation analysis. The results indicate that the angular displacement, angular velocity, and angular acceleration of the wing folding and retrieval mechanisms do not exhibit sudden spikes or abrupt drops, indicating a well-structured and smooth movement, with excellent motion characteristics. Specifically, by controlling the folding mechanism's driving rod to deflect from 83. 25° to 116. 75°, a folding angle deviation of 90° for the outer wing is achieved. Similarly, by controlling the retrieval mechanism's driving slider displacement of 516. 6 mm, a wing deployment angle of 90° is attained. Ultimately, the wing folding and retrieval operations are successfully completed within 30 seconds. [ABSTRACT FROM AUTHOR]

To enable visual tracking of targets by intermeshing-rotor unmanned helicopters in the presence of unstable global positioning system (GPS) signals, a visual tracking control system for intermeshing-rotor unmanned helicopters is designed. Firstly, a vision module is designed to perform image processing on tracked targets, obtain the pixel coordinates of the center point of the tracked target using oriented FAST and rotated BRIEF (ORB) feature matching and rectangle detection. Thus, the actual position of the center point of the tracked target is solved by the camera model and the rotation matrix. Secondly, a tracking control module is designed with a serial proportional-integral-derivative (PID) plus feed-forward control structure. An open-square controller is used in the position control in order to limit the limit position and maximum acceleration, and an intermeshing-rotor attitude control mechanism is designed in the attitude control. Then, the simulation environment is built by the flight control ground station to simulate and verify the flight control system with the added vision module. The results show that the unmanned helicopter can track the desired position output from the vision module very well. Finally, the experimental validation is conducted under the conditions of the maximum flight speed of 1 m/s, the maximum attitude angle of about 8°, and the maximum error of 0.08 m between the position and the desired position. The experiment demonstrates that the proposed system can fulfill the visual tracking of the intermeshing-rotor unmanned helicopter for the target. [ABSTRACT FROM AUTHOR]