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This paper presents the development of an autopilot system for self-driving an autonomous wheeled vehicle. A mathematical model, including the power allocation system, has been designed for a vehicle with three degrees of freedom. All model parameters have been identified through experimental trials. Heading and speed controllers were designed based on Lyapunov theory. These controllers have been further fine-tuned and tested through simulations to verify their robustness against external disturbances in the system dynamics. Moreover, this work proposes guidance approaches that allow the vehicle to track desired waypoints (line of sight (LOS)), and follow a given path (cross-track error) and a predefined trajectory with obstacle avoidance. A comparative study was also proposed in this paper, wherein we evaluate the paths followed by the vehicle using distinct yaw moment control techniques which are; differential thrust controller, solely relying on a steering controller, and a combination of both. To validate the effectiveness of the proposed autopilot system, we have conducted experimental tests, specifically focusing on waypoint tracking control (LOS method). The results underscore the system’s capabilities and its potential in real-world applications.

The Thrust vector control (TVC) is a method for controlling the angular velocity and attitude of aerial vehicles (AV) by manipulating the thrust direction of propulsion. This technology enhances maneuverability and allows for dynamic aerobatics at low speeds and near-zero airspeeds without stalling at high angles of attack (AOA). As the aerodynamic control surfaces are ineffective for vehicles operating outside the atmosphere, TVC is a suitable technique for these applications. To design a control system for AVs utilizing TVC, an accurate mathematical model is essential to simulate flight parameters and optimize the control gains. This work presents a complete six degrees-of-freedom (6-DOF) high-fidelity simulation model of a thrust vector control aerial vehicle (TVC-AV). The nonlinear model is developed by dividing the mathematical representation into five submodules, including the geometrical model, the actuation model that was experimentally identified, and an aerodynamic model that was validated through semi-empirical techniques, computational fluid dynamics (CFD), and wind-tunnel experiments; in addition, the propulsion model’s characteristics are identified through experimentation, and the atmospheric model is based on International Standard Atmosphere (ISA) values. The integrated model was implemented in MATLAB^Ⓡ (Simulink) that provides a foundation for designing effective flight controllers and guidance systems.

This paper presents the flexural behavior of notched steel beams repaired with carbon fiber-reinforced polymer (CFRP) strips. A combined experimental and computational approaches are used to examine local plasticity near the damage and the effects of CFRP-repair. A modeling approach is proposed to take into account the bond-slip behavior of CFRP-steel interface. The experimentally validated models are further used to conduct a parametric study addressing various engineering properties of CFRP composites and adhesives. The CFRP-repair is shown to restore the strength of the damaged beam. The CFRP strip relieves the stress concentration resulting from the presence of the notch, reducing the high local plasticity. The parametric study confirms the improved effectiveness of high modulus CFRP (i.e., exceeding 150 GPa) in affecting repairs of steel members. Under static loading conditions, the stiffness of the adhesive bond line influences the local behavior of the CFRP-steel interface but has little effect on the overall member behavior.

This paper presents a simplified modeling strategy for simulating the nonlinear behavior of reinforced concrete (RC) structures under seismic loadings. A new type of Euler–Bernoulli multifiber beam element with axial force and bending moment interaction is introduced. To analyze the behavior of RC structures in the axial direction, the interpolation of the axial strain is enriched using the incompatible modes method. The model uses the constitutive laws based on plasticity for steel and damage mechanics for concrete. The proposed multifiber element is implemented in the finite element Code_Aster to simulate the nonlinear behavior of two different RC structures. One structure is a building tested on a shaking table; the other is a column subjected to cyclic loadings. The comparison between the simulation and experimental results shows that the performance of this approach is quite good. The proposed model can be used to investigate the behavior of a wider variety of configurations which are impossible to study experimentally.

In this paper, we present a comprehensive design for a fully functional unmanned rotorcraft system: GremLion. GremLion is a new small-scale unmanned aerial vehicle (UAV) concept using two contra-rotating rotors and one cyclic swash-plate. It can fit within a rucksack and be easily carried by a single person. GremLion is developed with all necessary avionics and a ground control station. It has been employed to participate in the 2012 UAVForge competition. The proposed design of GremLion consists of hardware construction, software development, dynamics modeling and flight control design, as well as mission algorithm investigation. A novel computer-aided technique is presented to optimize the hardware construction of GremLion to realize robust and efficient flight behavior. Based on the above hardware platform, a real-time flight control software and a ground control station (GCS) software have been developed to achieve the onboard processing capability and the ground monitoring capability respectively. A GremLion mathematical model has been derived for hover and near hover flight conditions and identified from experimental data collected in flight tests. We have combined H_∞ technique, a robust and perfect tracking (RPT) approach, and custom-defined flight scheduling to design a comprehensive nonlinear flight control law for GremLion and successfully realized the automatic control which includes take-off, hovering, and a variety of essential flight motions. In addition, advanced mission algorithms have been presented in the paper, including obstacle detection and avoidance, as well as target following. Both ground and flight experiments of the complete system have been conducted including autonomous hovering, waypoint flight, etc. The test results have been presented in this paper to verify the proposed design methodology.

In this paper, mathematical model, control law design, different locomotion patterns, and locomotion planning are presented for an Anguilliform robotic fish. The robotic fish, consisted of links and joints, are driven by torques applied to the joints. Considering kinematic constraints, Lagrangian formulation is used to obtain the mathematical model of the robotic fish. The model reveals the relation between motion of the fish and external forces. Computed torque control method is first applied, which can provide satisfactory tracking performance for reference joint angles. To deal with parameter uncertainties, sliding model control is adopted. Three locomotion patterns — forward locomotion, backward locomotion, and turning locomotion — are realized by assigning appropriate reference angles to the joints, and the three locomotions are verified by experiments and simulations. A new form of central pattern generator (CPG) model is presented, which consists of three-dimensional coupled Andronov–Hopf oscillators, artificial neural network, and outer amplitude modulator. By using this CPG model, swimming pattern of a real Anguilliform fish is successfully applied to the robotic fish in an experiment.

Multirotors are well suited for application tasks such as surveillance and exploration of otherwise inaccessible areas. Standard quadrotors have limitations in their possible configurations due to their underactuation. For this reason, some spatial configurations are not possible, such as hovering while maintaining a nonhorizontal orientation. This paper presents an overactuated quadrotor platform with double axes tilting propellers. The peculiarity of the proposed platform is that, beside the usual control on the four propellers, it allows to tilt each arm where motors are mounted along two independent axis. The resulting number of control inputs is 12, allowing a higher number of stable configurations with respect to traditional quadrotors. As a result, it can assume spatial orientations that are not possible for traditional quadcopters, enabling the possibility to deal with obstacles that would generally impede the motion of normal quadcopters. This feature allows to potentially explore a larger space. This paper presents the design and modeling of the quadrotor. Numerical simulations are carried out to show the effectiveness of the proposed solution.

The growing utilization of unmanned aerial vehicles (UAVs) in military operations has necessitated the development of a suitable weaponry for these kind of platforms. One of the trending categories of such armaments is the aerial gliding vehicle (AGV). AGVs have no propulsion system, consequently, a critical need for a robust flight control system (FCS) tailored to this kind of aerial systems is raised. This research focuses on designing a nonlinear model based controller, starting with the construction of a precise model through practical experiments and the establishment of a dedicated testing and flight simulation environment. Recognizing the limitations of traditional nonlinear dynamic inversion (NDI) due to its dependence on the vehicle model, the modified incremental nonlinear dynamic inversion (MI-NDI) is developed to operate in the presence of wind, model mismatches, and external disturbances. In this research, an extensive testing is conducted in a hardware-in-the-loop (HIL) simulation environment which validates the MI-NDI controller’s superior performance, even in challenging conditions. The research outcomes mark a significant advancement in enhancing autopilot precision for advanced aerial weaponry and unmanned vehicles.

Environmentally responsible and minimal natural variation in electric power generation has been a goal of researchers for several decades. With the establishment of the electrical power generation potential from microalgae’s photosynthesis, several researchers revealed interesting microbial fuel cell configurations to improve the output of electrical parameters. However, little work is done to understand the electrical charge collected from photosynthesis. This article proposes a fuel cell-based electrochemical modeling of the micro-photosynthetic power cell. The model is developed, excluding significant analytical assumptions at stationary conditions. Due to the complexity of modeling the electron release from photosynthesis, the electron release reactions are substituted with a simpler redox coupler of similar electric potential to that of photosynthesis. The micro-photosynthetic power cell revealed that the electron collection rate does not directly correlate to the photosynthesis electron chain. It might remain constant for a specific electrical load. The peak power is obtained at a different operating loading than the internal resistance of the device. The experimental open circuit voltage ($\sim$0.96V) and the peak power ($\sim$0.18mW) are predicted accurately by this modeling approach. The results show that the fill factor remains constant with respect to several effective electrode surface areas. Based on this theoretical modeling, we believe that with optimized algal physiological state and micro-photosynthetic power cell’s effective surface area, this micro-photosynthetic power cell will be useful for application in low-power applications.

This paper is to understand and model the thermomechanical response of the rotary forged WHA, uniaxial compression and tension tests are performed on cylindrical samples, using a material testing machines and the split Hopkinson bar technique. True strains exceeding 40% are achieved in these tests over the range of strain rates from 0.001/s to about 7,000/s, and at initial temperatures from 77K to 1,073K. The results show: 1) the WHA displays a pronounced changing orientation due to mechanical processing, that is, the material is inhomogeneous along the section; 2) the dynamic strain aging occurs at temperatures over 700K and in a strain rate of 10^-3 1/s; 3) failure strains decrease with increasing strain rate under uniaxial tension, it is about 1.2% at a strain rate of 1,000 1/s; and 4) flow stress of WHA strongly depends on temperatures and strain rates. Finally, based on the mechanism of dislocation motion, the parameters of a physically-based model are estimated by the experimental results. A good agreement between the modeling prediction and experiments was obtained.