Isaac E. Weintraub

Wing Velocity Control System for Testing Body Motion Control Methods for Flapping Wing MAVs

This work is focused on testing the viability of split-cycle constant-period frequency modulation for controlling a flapping wing micro air vehicle. By varying the velocities of the upstroke and downstroke portions of a flapping wings’ motion, non-zero cycle-averaged drag can be generated. This results in the ability to control the roll and horizontal translation of the vehicle by varying the split-cycle parameter. In this paper, a flapping wing prototype is developed for testing the split-cycle technique. A fuselage, wings, motor control electronics, and motor control software are created to allow wireless control of the motion of the flapping wing vehicle. The complete vehicle is then placed on an air table for experimental testing. The air table provides the lift equal to weight condition and constrains the pitch and yaw degrees of freedom while allowing for roll rotation and horizontal translation. In this way, testing of the degrees of freedom which can be manipulated via split-cycle, namely roll and horizontal translation, can be performed. The air table tests reveal that split-cycle can be used to control these two degrees of freedom.

Control of a Minimally Actuated Biomimetic Vehicle Using Quarter-Cycle Wingbeat Modulation

This paper describes a technique, called quarter-cycle constant period frequency modulation, to control the motion of wings on a flapping wing micro-air vehicle. This technique allows control over the wingbeat period and three additional points (the two zero crossings and the reversal of wing direction) within a single wingbeat cycle, allowing modulation of the wing’s velocity to provide direct control over six degrees of freedom of overall vehicle motion. Using a blade element based aerodynamic model, both instantaneous and cycle-averaged forces and moments are analytically computed for a specific type of wingbeat motion that enables nearly decoupled, multi-degrees of freedom control of an aircraft. Wing motion is controlled using oscillators whose frequencies and three additional parameters change once per wingbeat cycle. A control oriented dynamic model of the vehicle is derived, which is based on a cycle-averaged representation of the forces and moments, and control derivatives are calculated. A cycle...

Implementation of Split-Cycle Control for Micro Aerial Vehicles

Flapping wing micro air vehicles have been of significant research interest in recent years due to the flight capabilities of their biological counterparts and their ability to hide in plain sight, inspiring applications for military and civilian surveillance. This work introduces the design, implementation, and fabrication of the circuitry used for split-cycle constant-period wingbeat capable flapping wing micro air vehicle platforms. Split-cycle constant-period modulation involves independent control of the upstroke and downstroke wing velocity profiles to provide the theoretical capability of manipulating five degrees of vehicle motion freedom using only two actuators, namely, a brushless direct current motor for each wing. The control circuitry mainly consists of a control circuit board, a wireless receiver, three micro-controllers, and drivers. The circuitry design is tested using a prototype vehicle mounted on an air-table platform. A human operated transmitter relays split-cycle constant-period commands to the vehicle to produce the desired vehicle motion.

Quarter Cycle Modulation of a Minimally Actuated Biomimetic Vehicle

This paper describes a technique, called quarter cycle constant-period frequency modulation, to control the motion of wings on a flapping wing micro air vehicle. This technique allows control over the wingbeat period and three additional points within a single wingbeat cycle, allowing modulation of the wing’s velocity to provide control over multiple degrees-of-freedom of the vehicle. Using a blade element based aerodynamic model, both instantaneous and cycle averaged forces and moments are analytically computed for a specific type of wing beat motion that enables nearly decoupled, multiple degrees-of-freedom control of the aircraft. The wing positions are controlled using oscillators whose frequencies change once per wing beat cycle. A control oriented dynamic model of the vehicle is derived, which is based on a cycle averaged representation of the forces and moments. Control derivatives are calculated and a cycle-averaged control law is designed that provides control over multiple degrees-of-freedom of the vehicle.

Development of a Flapping Wing Mechanism that Can Produce Lift Greater than Weight

This work is focused on testing multiple versions of flapping wing mechanisms to improve the lift generating capabilities of the mechanisms. Three mechanisms are considered in this work, a traditional four bar linkage version, a four bar mechanism which used ball joints, and a four bar mechanism with a sector and output gear for amplified motion. The traditional four bar version has a wing stroke amplitude of about 55 while the other two mechanisms have an amplitude of nearly 90. The criteria for comparison is the lift force generating capacity of each mechanism. For each mechanism, the forward kinematics are derived for use in a table lookup so that symmetric and asymmetric flapping can be achieved as desired.

Computation of inertial forces and torques associated with flapping wings

Typically, inertial loads associated with flapping wing micro air vehicles are ignored for analysis and control law development purposes. The goal of this work is to compute the inertial loads associated with flapping a wing and compare those loads to aerodynamic loads. It is assumed that the wing is a rigid flat plate so that there is no in-plane, out-of-plane, or torsional bending of the wing. The analysis begins by computing the acceleration of the wing center-of-gravity over a complete wingbeat cycle. Newton’s second law is then used to compute the inertial forces and eventually, the inertial moments. Simulation results are provided which compare the magnitude of the inertial loads to the aerodynamic loads for a wing of varying geometry.

Kinematic Selection for a Tailless Flapping Wing Micro-Air Vehicle

A flapping wing micro air vehicle, which utilizes a four-bar linkage with amplified gearing to convert rotary motion of the prime movers into oscillatory motion of the wings, is described in this work. The four-bar linkage yields an asymmetric wingstroke, where the first half and second half of the wingstroke do not have the same angular velocity. This asymmetry results in undesired fore or aft translation and roll of the vehicle, which must be canceled with control effort in order to hover. During experiments, it was found that a large amount of control authority was required to trim out these undesired motions, leaving only a small amount of control authority for maneuvering. In this work, the four-bar linkage is optimized to reduce the asymmetric wingstroke and provide more constant torque transmission throughout the entire stroke. Experimental results show an improvement in the symmetry of the wingstroke after kinematic optimization. ∗Scientist, Aerospace Vehicles Technology Assessment and Simulation Branch, 2210 Eighth Street, Bldg. 145, Air Force Research Laboratory, WPAFB, OH 45433-7531 Email: isaac.weintraub.1@us.af.mil, Ph. (937) 255-4459 †Principal Engineer, General Dynamics Information Technology, 2210 Eighth Street, Bldg. 146, Rm. 304A, WPAFB, OH 45433-7531 Email: David.Sigthorsson.ctr.is@us.af.mil, Ph. (937) 255-4512, Member, AIAA ‡Senior Electronics Engineer, Autonomous Control Branch, 2210 Eighth Street, Bldg. 146, Rm. 305, Air Force Research Laboratory, WPAFB, OH 45433-7531 Email michael.oppenheimer@us.af.mil, Ph. (937) 713-7020, Associate Fellow, AIAA §Principal Aerospace Engineer, Autonomous Control Branch, 2210 Eighth Street, Bldg. 146, Rm. 305, Air Force Research Laboratory, WPAFB, OH 45433-7531 Email david.doman@us.af.mil, Ph. (937) 713-7003, Fellow AIAA

Experimental Measurements of Cycle Averaged Forces for a Flapping Wing Vehicle

In this work, experimental measurements of cycle-averaged forces produced by a flapping wing micro air vehicle are provided. The measurements are taken with a one degree-of-freedom force balance. The vehicle is mounted in different orientations so that cycle-averaged lift and drag can be measured. A variety of wing flapping frequencies are examined as well as different split-cycle parameters. The cycle-averaged measurements are compared to theoretical values obtained with a blade element model. The primary objective of this work is to determine if a blade element based aerodynamic model can accurately predict the cycle-averaged forces produced by wing flapping.