Mujahid Abdulrahim

University of Florida | UF · Department of Mechanical and Aerospace Engineering

Micro-air vehicles (MAVs) are envisaged to spend a large portion of their mission within urban environments, which in general are rich in large obstacles (both natural and man-made). These obstacles can be a hindrance to MAV flight, but also have the potential to generate orographic updrafts when wind impinges on them. In theory, MAVs can exploit t...

Strategies for forward-sensing turbulence ahead of an aircraft are introduced, which enable more timely opposing control inputs than for traditional inertial sensing. Typically traditional systems measure the effect of a velocity perturbation on an aircraft and thus can only provide a delayed response when countering the effect. The early acquisiti...

There are significant challenges associated with the flight control of fixed-wing micro air vehicles (MAVs) operating in complex environments. The scale of MAVs makes them particularly sensitive to atmospheric disturbances thus limiting their ability to sustain controlled flight. Bio-inspired, phase-advanced sensors have been identified as promisin...

Fixed-wing Micro-Aerial Vehicles (MAVs) need effective sensors that can rapidly detect turbulence induced motion perturbations. Current MAV attitude control systems rely on inertial sensors. These systems can be described as reactive; detecting the disturbance only after the aircraft has responded to the disturbing phenomena. In this part of the pa...

There are significant challenges in the control of fixed-wing Micro Air Vehicles (MAVs) in high turbulence environments. Birds can sustain stable flight in such environments by obtaining flow information through mechanoreceptors embedded in their wings. Inspired by nature’s flyers, an investigation into replicating the function of mechanoreceptors...

Challenges associated with flight control of agile fixed-wing Micro Air Vehicles (MAVs) operating in complex environments is significantly different to any larger scale vehicle. The micro-scale of MAVs can make them particularly sensitive to atmospheric disturbances thus limiting their operation. As described in Part 1, current conventional reactiv...

In the last several years, we have developed unique types of micro air vehicles that utilize flexible structures and extensible covering materials. These MAVs can be operated with maximum dimensions as small as 6 inches and carry reasonable payloads, such as video cameras and transmitters. We recently demonstrated the potential of these vehicles by...

Flight capability for micro air vehicles is rapidly maturing throughout the aviation community; however, mission capability has not yet matured at the same pace. Maintaining trim during a descent or in the presence of crosswinds remains challenging for fixed-wing aircraft but yet is routinely performed by birds. This paper presents an overview of d...

Air vehicle flight in turbulence is generally treated as an anomalous part of the flying environment. Aircraft geometries and flight-control systems are often designed and tested for calm atmospheric conditions, where both steady winds and gusts are minor. As a result, the flight performance of small aircraft deteriorates in the presence of atmosph...

This report is the research summary of flying MAV experiments in turbulent flow, utilizing prior research measuring and reproducing aspects of the outdoor environment. Turbulence was replicated in a large wind engineering tunnel and was well mixed, thus replicating atmospheric turbulence under neutrally stable conditions far removed from local effe...

Major challenges to low speed micro flight are the transient and time-averaged velocities arising from the Atmospheric Boundary Layer (ABL), particularly turbulence a few metres above the ground. In this paper, existing data from meteorologists and wind engineers are reviewed and measurements dedicated to understanding the spatial and temporal velo...

Micro air vehicle ∞ight in turbulence is generally treated as an anomalous part of the ∞ying environment. Aircraft geometries and ∞ight control systems are often designed and tested for calm atmospheric conditions, where both steady winds and gusts are minor. As a result, the ∞ight performance of MAVs deteriorates in the presence of atmospheric tur...

Aspects of the turbulent wind environment Micro Air Vehicles (MAVs) experience when flying outdoors were replicated in a large wind tunnel. An overview of the facility, instrumentation and initial flight tests is given. Piloting inputs and aircraft accelerations were recorded on fixed and rotary wing MAVs and for some tests, measurements of the app...

Major challenges to low speed micro flight are the transient and time-averaged velocities arising from the Atmospheric Boundary Layer (ABL), particularly turbulence a few metres above the ground. In this paper, existing data from meteorologists and wind engineers are reviewed and measurements dedicated to understanding the spatial and temporal velo...

A class of micro air vehicles uses a flexible membrane wing for weight savings and passive shape adaptation. Such a wing is not amenable to conventional aileron mechanisms for roll control, due to a lack of internal wing structure. Therefore, morphing (in the form of asymmetric twisting) is implemented through the use of a torque-actuated wing stru...

Natural flight as a source of inspiration for aircraft design was prominent with early aircraft but became marginalized as aircraft became larger and faster. With recent interest in small unmanned air vehicles, biological inspiration is a possible technology to enhance mission performance of aircraft that are dimensionally similar to gliding birds....

Birds are perhaps the most versatile and graceful flying objects in the atmosphere. Even in complex urban environments, they are able to rapidly change shape to transition from efficient cruise to aggressive maneuvering and precision descents. Avian morphology permits a wide range of wing configurations, each of which may be used for a particular f...

Morphing, which changes the shape and configuration of an aircraft, is being adopted to expand mission capabilities of aircraft. The introduction of biologically-inspired morphing is particularly attractive in that highly-agile birds present examples of aerodynamically-effective shapes. This paper introduces an aircraft with a multiple-joint design...

Morphing is attractive as a control effector that can dramatically alter the flight characteristics of an aircraft. In particular, morphing can use biologically-inspired approaches that note the similarity in size and airspeed between a micro air vehicle and birds. This paper introduces several types of morphing that have been implemented and flown...

A class of micro air vehicles (MAVs) developed and tested at the University of Florida use a flexible membrane wing as an effective means of gust rejection. Such a wing is not amenable to conventional aileron mechanisms for roll control due to a lack of internal wing structure. Therefore, morphing (in the form of asymmetric wing twisting) is implem...

Driving at large angles of sideslip does not necessarily in-dicate terminal loss of control, rather, it is the fundamental objective of the sport of drifting. Drift racing challenges drivers to navigate a course in a sustained sideslip by ex-ploiting coupled nonlinearities in the tire force response. The current study explores some of the physical...

Missions envisioned for micro air vehicles may require a high degree of autonomy to operate in unknown environments. As such, vision is a critical technology for mission capability. This paper discusses an autopilot that uses vision coupled with GPS and altitude sensors for waypoint navigation. The vision processing analyzes a horizon to estimate r...

Despite the past century of innovation in aircraft technology, the versatility of modern aircraft remains far worse than airborne biological counterparts. The shape changing accomplished by birds and bats in ight stands as one of the few examples of true morphing. As such, the aircraft community is devoting considerable attention to the study of bi...

Biologically inspired concepts are rapidly expanding the range of aircraft technology. Consideration is given to merging two biologically-inspired concepts, morphing and micro air vehicles, and the resulting flight characteristics are investigated. Specifically, wing shaping is used to morph the membrane wings of a micro air vehicle. The micro air...

Contemporary morphing designs are focused towards enabling a vehicle to transition from one distinct flight regime to another. Such a change often requires highly complex morphing that is designed to address both aerodynamic performance and handling criteria. The University of Florida has developed a morphing demonstrator to investigate the effect...

Micro air vehicles are able to fly in environments with little maneuvering room; however, such flight re-quires high agility and precision maneuvering. A current class of micro air vehicle is constructed with only rudder and elevator for control authority. Such surfaces are not optimal for flight control but ailerons can not be installed on the mem...

A micro air vehicle is a ight system being designed for operation within urban environments. Such vehicles are small and highly agile but often have limited control authority. This paper investigates the use of morphing as an effector to provide control authority. Simple mechanisms for morphing are designed to twist the wings of a 24 in vehicle and...

Flight researchers are increasingly turning towards small, unmanned aircraft for achieving mission objectives. These aircraft are simple to operate and offer numerous advantages over larger manned vehicles. In addition to being light, inexpensive, and readily available, they are also more versatile in that they can be used for flight experiments th...

Missions envisioned for micro air vehicles, such as ur- ban surveillance, require exceptional agility. Their size allows ight operations within conned spaced but the control effectors must provide sufcient maneuverabil- ity for those ight operations. This paper discusses a program to investigate morphing as control effectors for micro air vehicles....

This paper explains and illustrates the development of flexible-wing Micro Air Vehicles (MAVs) at the University of Florida (UF). The UF MAV team used different design objectives to create an endurance vehicle as well as a surveillance vehicle. This paper shows the design intent and approach, identifying airplane components, fabrication techniques,...

ABSTRACT: The research presented in this thesis is an approach to the study of flight dynamics of morphing vehicles. Case studies of several strategies are addressed in order to determine some of the basic flight characteristics of dynamically and quasi-statically morphing aircraft. These strategies include a flexible membrane wing that uses tensio...