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Design and Evaluation of a Multirotor Vibration Damping System for a Large Cable-Driven Parallel Manipulator
Recently, the idea of cable-driven parallel manipulators has been applied to field phenotyping, which is a process requiring automated and repeatable measurement of the growth traits of plants to help increase agriculture productivity. Compared to conventional field phenotyping strategies, cable-driven based field phenotyping systems demonstrate promising advantages with minimal infrastructure, automatic control, repeatable positioning, and scalability to a larger range of field dimensions and shapes. A drawback of this type of system, however, is its limited ability to reject excessive vibration at the end effector due to the low effective stiffness of long, sagging cables. In agricultural phenotypic studies, there are several sensors and cameras that require prolonged exposure times, and so platform vibrations can compromise the sensor readings, which further increase the settling time of the end effector and decrease the efficiency of the system. This study proposed and evaluated the feasibility of using a multirotor system for vibration damping of a cable-driven field phenotyping platform constructed at the University of Nebraska for scanning crop experiments in a one-acre field. The design, implementation, and experimental validation of a multirotor vibration damping system are presented in detail. By comparing the stability of the end effector of the CDPM with and without the multirotor system during operation, the results show that the multirotor system reduces the vibration amplitude of a 75 kg end effector from 5 cm to 1 cm (our target vibration amplitude) within 5 seconds or less compared to the average of 15 seconds for the undamped system. This will result in a total time savings of more than 1 hour per day for imaging crops, which represents an improvement of about 25% of the overall system scanning efficiency.
Sun, Yue, "Design and Evaluation of a Multirotor Vibration Damping System for a Large Cable-Driven Parallel Manipulator" (2019). ETD collection for University of Nebraska - Lincoln. AAI22588694.