This paper considers actuator redundancy management for a class of overactuated nonlinear systems. Two tools for distributing the control effort among a redundant set of actuators are optimal control design and control allocation. In this paper, we investigate the relationship between these two design tools when the performance indexes are quadratic in the control input. We show that for a particular class of nonlinear systems, they give exactly the same design freedom in distributing the control effort among the actuators. Linear quadratic optimal control is contained as a special case. A benefit of using a separate control allocator is that actuator constraints can be considered, which is illustrated with a flight control example.

Resolving actuator redundancy: optimal control vs. control allocation

AIAA Guidance, Navigation, and Control Conference

Wheel slip control for ground vehicles with individually controlled electric motors can be realized with strategies that can significantly differ from the conventional antilock braking system (ABS) and traction control (TC) system. This paper provides a review of state-of-the-art technology and recent developments in TC and ABSs using the actuation of electric motors. Particular attention is paid to the realization of slip estimators, the formalization of torque demand, and the control methods applied for the implementation of TC and ABSs. The performed analysis allowed for the differentiation of several most elaborated methods for slip and torque control and defining still imperfectly investigated problems to be covered by the further development of TC and ABSs for full electric vehicles.

A Survey of Traction Control and Antilock Braking Systems of Full Electric Vehicles With Individually Controlled Electric Motors

Synthesis Of Subsonic Airplane Design

An acceleration measurements-based approach for helicopter nonlinear flight control using Incremental Nonlinear Dynamic Inversion

The potential environmental benefits of hybrid electric regional turboprop aircraft in terms of fuel consumption are investigated. Lithium–air batteries are used as energy source in combination with conventional fuel. A validated design and analysis framework is extended with sizing and analysis modules for hybrid electric propulsion system components. In addition, a modified Breguet range equation, suitable for hybrid electric aircraft, is introduced. The results quantify the limits in range and performance for this type of aircraft as a function of battery technology level. A typical design for 70 passengers with a design range of 1528 km, based on batteries with a specific energy of 1000 Wh/kg, providing 34% of the shaft power throughout the mission, yields a reduction in emissions by 28%.

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Analysis and design of hybrid electric regional turboprop aircraft

Several research studies indicate that the Blended Wing Body concept offers a significant performance improvement compared to conventional civil transportation aircraft due to its efficient aerodynamic configuration. Technical challenges are currently present in nearly all key areas of the design of a Blended Wing Body aircraft as a result of its highly integrated design. The aim of the current research is the development of a tool that automatically generates a nonlinear flight mechanics model of a Blended Wing Body aircraft within a Multidisciplinary Design Optimization framework. The main purpose of the model is to assess the controllability of the aircraft in the conceptual design phase via desktop and piloted simulation. Specific topics of interest to be investigated are handling qualities in normal operation and with failure states present. The model will also serve as a baseline for the development of control allocation schemes. Results obtained by analyzing the model can be used for the preliminary design of the aerodynamic control surfaces in terms of size, position and arrangement.

/pdf/controllability-of-blended-wing-body-aircraft-3ntjh232o7.pdf

Controllability of blended wing body aircraft

The conceptual and preliminary design of a 300-passenger box-wing aircraft configuration, designated the PrandtlPlane, is investigated. Currently there are still a number of technical issues which must be investigated thoroughly to demonstrate the feasibility of this configuration. This research study is focused on two aspects of the PrandtlPlane design, (1) the propulsion system and (2) the flight control system. A nonlinear aircraft model is created with an in-house developed flight mechanics toolbox, which is designed for its application in the conceptual and preliminary design phase. The resulting propulsion system design has two conventional turbofan engines at the tail of the aircraft. For a large version of the PrandtlPlane, it might be beneficial to consider large open-rotor systems underneath the rear wing. The volume of the wing system, which is smaller than that of conventional aircraft, poses constraints on the fuel system design. Flight control of the PrandtlPlane is quite different from the control of conventional aircraft. If control surfaces are placed on the front and rear wings, then a pure moment can be created by differential deflection of these controls. Furthermore, a combined deflection of the front and rear wing control surfaces allows the use of direct lift control. The aircraft exhibits good inherent handling qualities in the longitudinal axis. The Dutch roll mode is slightly unstable. Improvements are expected if the vertical tails of the aircraft are redesigned. Finally, a model-based inversion flight control law is presented which provides a rate command response type in all axes. An additional outer control loop is designed which provides direct lift control. The control law is tested on the nonlinear aircraft model and demonstrates the potential of the PrandtlPlane control characteristics.

Flight Mechanics Modeling of the PrandtlPlane for Conceptual and Preliminary Design

This paper describes the development and validation of a high fidelity simulation model of the Bell 412 helicopter for handling qualities and flight control investigations. The base-line model features a rigid, articulated blade-element formulation of the main rotor, with flap and lag degrees of freedom. The Bell 412 HP engine/governor dynamics are represented by a second-order system. Other key features of the base-line model include a finite-state dynamic inflow model and lag damper dynamics. The base-line model gives excellent agreement with flight-test data over the speed range 15-120kt for on-axis responses. Prediction of off-axis responses is less accurate. Several model enhancement options were introduced to obtain an improved off-axis response. It is shown that the pitch/roll off-axis responses in transient manoeuvres can be improved significantly by including wake geometry distortion effects in the Peters-He finite-state dynamic inflow model.

Rotorcraft simulation modelling and validation for control law design

This paper presents a methodology for the design of the primary flight control surfaces, in terms of size, number and location, for fixed wing aircraft (conventional or unconventional). As test case, the methodology is applied to a 300 passenger variant of the Prandtl Plane. This box wing aircraft is deemed to have low induced drag compared to conventional aircraft. The methodology is completely physics based and includes an aerodynamic analysis, followed by a control allocation algorithm and an analysis of the flight mechanics. The design has to fulfill a set of handling qualities requirements with a minimum total control surface area. An optimization algorithm is used to find the best design. Results indicate that this is possible with ailerons outboard on both wings, elevators inboard on both wings and conventional rudders in the vertical tail. The configuration allows for pure torque control and also direct lift control in the longitudinal axis. These features can potentially enhance airfield performance.

/pdf/automated-control-surface-design-and-sizing-for-the-prandtl-5gmhd8dtm8.pdf

Mark Voskuijl

Papers

Analysis and design of hybrid electric regional turboprop aircraft

Controllability of blended wing body aircraft

Flight Mechanics Modeling of the PrandtlPlane for Conceptual and Preliminary Design

Rotorcraft simulation modelling and validation for control law design

Automated Control Surface Design and Sizing for the Prandtl Plane