Handling qualities of fixed-pitch, variable-speed multicopters for urban air mobility

2021 ◽  
pp. 1-21
Author(s):  
M. Bahr ◽  
M. McKay ◽  
R. Niemiec ◽  
F. Gandhi
Keyword(s):  
Longitudinal Velocity ◽  
Control Design ◽  
Weight Fraction ◽  
Urban Air ◽  
Variable Speed ◽  
Handling Qualities ◽  
Motor Current ◽  
Current Requirement ◽  
Maximum Current ◽  
Reaction Torque

Abstract Optimisation-based control design techniques are applied to multicopters with variable-RPM rotors. The handling qualities and motor current requirements of a quadcopter, hexacopter and octocopter with equal gross weights (5,360N) and total disk areas (producing a 287N/m $^2$ disk loading) are compared in hover. For axes that rely on the rotor thrust (all except yaw), the increased inertia of the larger rotors on the quadcopter increase the current requirement, relative to vehicles with fewer, smaller rotors. Both the quadcopter and hexacopter have maximum current margin requirements (relative to hover) during a step command in longitudinal velocity. In yaw, rotor inertia is irrelevant, as the reaction torque of the motor is the same whether the rotor is accelerating or overcoming drag. This, combined with the octocopter’s greater inertia as well as the fact that it requires 30% less current to drive its motors in hover, results in the octocopter requiring the greatest current margin, relative to hover conditions. To meet handling qualities requirements, the total weight of the motors of the octocopter and hexacopter is comparable at 13.5% weight fraction, but the quadcopter’s motors are heavier, requiring 16% weight fraction. If the longitudinal and lateral axes were flown in ACAH mode, rather than TRC mode, the total motor weight of all configurations would be nearly identical, requiring about 13.5% weight fraction for motors (compared to 7–9% weight fraction from hover torque requirements).

scholarly journals Two Current-Based Methods for the Detection of Bearing and Impeller Faults in Variable Speed Pumps

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4514
Author(s):  
Vincent Becker ◽  
Thilo Schwamm ◽  
Sven Urschel ◽  
Jose Alfonso Antonino-Daviu
Keyword(s):  
Condition Monitoring ◽  
False Alarms ◽  
Signature Analysis ◽  
Variable Speed ◽  
Monitoring Methods ◽  
Time Frequency ◽  
Motor Current ◽  
Load Point ◽  
Bearing Defects ◽  
Current Signature

The growing number of variable speed drives (VSDs) in industry has an impact on the future development of condition monitoring methods. In research, more and more attention is being paid to condition monitoring based on motor current evaluation. However, there are currently only a few contributions to current-based pump diagnosis. In this paper, two current-based methods for the detection of bearing defects, impeller clogging, and cracked impellers are presented. The first approach, load point-dependent fault indicator analysis (LoPoFIA), is an approach that was derived from motor current signature analysis (MCSA). Compared to MCSA, the novelty of LoPoFIA is that only amplitudes at typical fault frequencies in the current spectrum are considered as a function of the hydraulic load point. The second approach is advanced transient current signature analysis (ATCSA), which represents a time-frequency analysis of a current signal during start-up. According to the literature, ATCSA is mainly used for motor diagnosis. As a test item, a VSD-driven circulation pump was measured in a pump test bench. Compared to MCSA, both LoPoFIA and ATCSA showed improvements in terms of minimizing false alarms. However, LoPoFIA simplifies the separation of bearing defects and impeller defects, as impeller defects especially influence higher flow ranges. Compared to LoPoFIA, ATCSA represents a more efficient method in terms of minimizing measurement effort. In summary, both LoPoFIA and ATCSA provide important insights into the behavior of faulty pumps and can be advantageous compared to MCSA in terms of false alarms and fault separation.

Control Design for Cancellation of Unnatural Reaction Torque and Vibrations in Variable-Gear-Ratio Steering System

2013 ◽  
Author(s):  
Atsushi Oshima ◽  
Xu Chen ◽  
Sumio Sugita ◽  
Masayoshi Tomizuka
Keyword(s):  
Control Method ◽  
Low Frequency ◽  
Control Design ◽  
Steering System ◽  
Gear Ratio ◽  
Experimental Setup ◽  
Hardware In The Loop ◽  
Model Uncertainties ◽  
Reaction Torque

Variable-gear-ratio steering is an advanced feature in automotive vehicles. As the name suggest, it changes the steering gear ratio depending on the speed of the vehicle. This feature can simplify steering for the driver, which leads to various advantages, such as improved vehicle comfort, stability, and safety. One serious problem, however, is that the variable-gear-ratio system generates unnatural torque to the driver whenever the variable-gear-ratio control is activated. Such unnatural torque includes both low-frequency and steering-speed-dependent components. This paper proposes a control method to cancel this unnatural torque. We address the problem by using a tire sensor and a set of feedback and feedforward algorithms. Effectiveness of the proposed method is experimentally verified using a hardware-in-the-loop experimental setup. Stability and robustness under model uncertainties are evaluated.

scholarly journals Power Control Design for Variable-Speed Wind Turbines

Energies ◽  
2012 ◽  
Vol 5 (8) ◽  
pp. 3033-3050 ◽  
Author(s):  
Yolanda Vidal ◽  
Leonardo Acho ◽  
Ningsu Luo ◽  
Mauricio Zapateiro ◽  
Francesc Pozo
Keyword(s):  
Power Control ◽  
Wind Turbines ◽  
Control Design ◽  
Variable Speed

Robust control design of variable speed wind turbine using quantitative feedback theory

2018 ◽  
Vol 232 (6) ◽  
pp. 691-705 ◽  
Author(s):  
Navdeep Singh ◽  
Bhanu Pratap ◽  
Akhilesh Swarup
Keyword(s):  
Robust Control ◽  
Wind Turbine ◽  
Control Design ◽  
Control Technique ◽  
Effective Control ◽  
Quantitative Feedback Theory ◽  
Variable Speed ◽  
Variable Speed Wind Turbine ◽  
Wide Range ◽  
Robust Control Design

A robust control design of a three blade, horizontal axis variable speed wind turbine is developed in this paper. The variable speed wind turbine model consists of higher order nonlinear dynamics where uncertainty has been considered in the plant parameters. Quantitative feedback theory is an effective and efficient, robust control technique through which the desired specifications over a specified range of parametric uncertainty can easily be achieved in the frequency domain. The proposed robust torque and pitch control in variable speed wind turbine using quantitative feedback theory satisfy prescribed gain and phase margin, degree of tracking for the robust performance, fast convergence, noise attenuation, and input and output disturbance rejection. The advantages of the proposed robust control design are the consideration of a wide range of performance specifications and achieving effective control over an increased operating frequency range. The simulation results demonstrate the satisfactory performance of proposed quantitative feedback theory-based controller and prefilter which fulfill the necessary conditions such as robust stability and robust tracking. Further, it has been shown that the performance of the quantitative feedback theory-based controller is better than the performance with a standard wind turbine controller and also from the performance by proportional-integral controller.

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