Landing Guidance System Research Articles

Research on Unmanned Aerial Vehicle (UAV) Visual Landing Guidance and Positioning Algorithms

Considering the weak resistance to interference and generalization ability of traditional UAV visual landing navigation algorithms, this paper proposes a deep-learning-based approach for airport runway line detection and fusion of visual information with IMU for localization. Firstly, a coarse positioning algorithm based on YOLOX is designed for airport runway localization. To meet the requirements of model accuracy and inference speed for the landing guidance system, regression loss functions, probability prediction loss functions, activation functions, and feature extraction networks are designed. Secondly, a deep-learning-based runway line detection algorithm including feature extraction, classification prediction and segmentation networks is designed. To create an effective detection network, we propose efficient loss function and network evaluation methods Finally, a visual/inertial navigation system is established based on constant deformation for visual localization. The relative positioning results are fused and optimized with Kalman filter algorithms. Simulation and flight experiments demonstrate that the proposed algorithm exhibits significant advantages in terms of localization accuracy, real-time performance, and generalization ability, and can provide accurate positioning information during UAV landing processes.

Tianwen-1 Entry, Descent, and Landing Guidance, Navigation, and Control System Design and Validation

On 15 May 2021, the Tianwen-1 mission delivered a lander and the Zhurong rover to the Mars surface, which made China the second nation to successfully land and place a rover on that planet. The guidance, navigation, and control (GNC) system for the entry, descent, and landing (EDL) of the Tianwen-1 mission play keys role in guaranteeing a successful landing. In this paper, the Tianwen-1 EDL GNC system design is presented, including the GNC architecture, scheme, and algorithm; additionally, the system is validated through experimental tests, numerical simulations, and actual flight results from telemetry data.

Braking and attitude control of lunar lander in active descent stage

Abstract China officially launched the lunar exploration project, named “Chang’e Project,” in 2004. Then, in 2013, Chang’e-3 completed the soft landing on the lunar surface, starting a series of studies on the soft landing of spacecraft. This study aims to optimize the dynamic flight guidance and attitude control of the lunar landing module represented by Chang’e-3 in the soft landing stage. After analyzing the attitude control requirements of the soft landing stage of the lunar landing module, this study designs the lunar soft landing process under a variable structure sliding mode (VSSM) control. The study also analyzes the influence of the pulse width modulator (PWM) on the soft landing process. The simulation model of the lunar soft landing guidance and control system is established by MATLAB/Simulink, and the traditional proportional–integral–derivative (PID) control mode is compared with the interference condition. Results show that VSSM + PWM is superior to PID in robustness and accuracy and has a theoretical reference value for future lunar landing exploration and even Mars landing exploration.

Research on the Design of UAV Relay Charging High-rise Platform for Electrical Equipment Live Detection in Substation

The multi-rotor UAV inspection technology has received extensive attention in the live detection of electrical equipment in substations and has begun to be practically applied. However, due to the short endurance and the characteristics of intermittent operations, the UAV needs to frequently travel between the operational airspace and the cabin, which seriously affects the operational efficiency of the inspection. This paper first introduces the traditional substation electrical equipment live detection technology and then summarizes the application of UAV inspection in the substation electrical equipment live detection. Finally, in view of the shortcomings of the existing technology, this paper proposes a design scheme of a relay-charging high-rise platform for live detection and inspection of electrical equipment in substations. The relay charging high-rise platform can be divided into six parts according to the functional structure: high-altitude apron, UAV landing guidance system, UAV automatic binding system, high insulation strength power supply system, and platform monitoring system. In this paper, the overall structure of the relay charging high-level platform and the technical solutions of each component are described in detail. The technical solution can effectively improve the efficiency and safety of multi-rotor UAV inspection operations for live detection of electrical equipment in substations.

Automatic Landing for Carrier-Based Aircraft Under the Conditions of Deck Motion and Carrier Airwake Disturbances

This article studies the automatic landing problem for the carrier-based aircraft in the presence of deck motion and carrier airwake disturbance. First, an automatic regressive model based prediction algorithm is proposed to generate the motion information of the deck, which in turn is used to generate corrections in the commands of the aircraft's heading and flight path to guarantee landing accuracy. Then, a fast fixed-time stable system (FFSS) is proposed. Based on the FFSS, the sliding-mode-based command differentiators are designed to estimate the first-order derivatives of the reference commands in finite time. Moreover, using the modified reaching law, the incremental sliding mode control (ISMC) is presented to design the landing guidance and control system to provide fast and accurate flight control to touchdown, where the airwake disturbances are compensated by the designed adaptive super twisting extended state observers (ASTESOs). Besides, to improve the stability during the final approach, an approach power compensation subsystem maintaining the angle of attack is proposed using the ISMC and ASTESO. The stability of the closed-loop system is analyzed using the Lyapunov theorem. Finally, comparative simulation results demonstrate the effectiveness of the proposed control scheme over state-of-the-art methods on the landing accuracy and robustness.

Prediction and Compensation Model of Longitudinal and Lateral Deck Motion for Automatic Landing Guidance System

This paper mainly studies the longitudinal and lateral deck motion compensation technology. In order to ensure the safe landing of the carrier-based aircrafts on the flight decks of carriers during the landing process, it is necessary to introduce deck motion information into the guidance law information of the automatic landing guidance system when the aircraft is about to land so that the aircraft can track the deck motion. To compensate the influence of the height change in the ideal landing point on the landing process, the compensation effects of the deck motion compensators with different design parameters are verified by simulation. For further phase-lead compensation for the longitudinal automatic landing guidance system, a deck motion predictor is designed based on the particle filter optimal prediction theory and the AR model time series analysis method. Because the influence of up and down motions on the vertical motion of the ideal landing point is the largest, the compensation effects of the designed predictor and compensator are simulated and verified based on the up and down motion of the power spectrum. For the compensation for the lateral motion, a tracking strategy of the horizontal measurement axis of the inertial stability coordinate system to the horizontal axis of the hull coordinate system (center line of the deck) is proposed. The tracking effects of the horizontal measurement axis of the designed integral and inertial tracking strategies are simulated and compared. Secondly, the lateral deck motion compensation commands are designed, and the compensation effects of different forms of compensation commands are verified by simulations. Finally, the compensation effects for the lateral deck motion under integral and inertial tracking strategies are simulated and analyzed.

Visual-based Landing Guidance System of UAV with Deep Learning Technique for Environments of Visual-detection Impairment

Visual-based Landing Guidance System of UAV with Deep Learning Technique for Environments of Visual-detection Impairment

Proactive Guidance for Accurate UAV Landing on a Dynamic Platform: A Visual-Inertial Approach.

This work aimed to develop an autonomous system for unmanned aerial vehicles (UAVs) to land on moving platforms such as an automobile or a marine vessel, providing a promising solution for a long-endurance flight operation, a large mission coverage range, and a convenient recharging ground station. Unlike most state-of-the-art UAV landing frameworks that rely on UAV onboard computers and sensors, the proposed system fully depends on the computation unit situated on the ground vehicle/marine vessel to serve as a landing guidance system. Such a novel configuration can therefore lighten the burden of the UAV, and the computation power of the ground vehicle/marine vessel can be enhanced. In particular, we exploit a sensor fusion-based algorithm for the guidance system to perform UAV localization, whilst a control method based upon trajectory optimization is integrated. Indoor and outdoor experiments are conducted, and the results show that precise autonomous landing on a 43 cm × 43 cm platform can be performed.

Improved Non-Fragile State Feedback Control for Stochastic Jump Systems With Uncertain Parameters and Mode-Dependent Time-Varying Delays

This paper reports the investigation on non-fragile state feedback control for stochastic Markovian jump systems with uncertain parameters and mode-dependent time-varying delays. The resulted closed-loop system is stochastic stabilization by virtue of an improved L-K functional. By free-weight-matrix technique, the non-fragile state feedback controller is designed and novel conditions for robust stochastic stabilization are acquired in the form of linear matrix inequalities. Two examples including a take-off and landing guidance system are employed to show the effectiveness and validity of the proposed approach.

A Vision/Radar/INS Integrated Guidance Method for Shipboard Landing

This paper presents a vision/radar/INS integrated guidance system for shipboard landing. The vision system on the aircraft tracks landmarks on the ship and outputs their coordinates in the image. The motion information of aircraft is obtained from airborne inertial navigation system (INS). Meanwhile, the datalink receives the relative position between the ship and aircraft from the shipboard radar and the ship motion information from shipboard sensors. The federated filter is utilized to fuse the vision, radar and inertial information, and the information from INS is chosen as the reference system in the federated filter. The estimated ship motion information is utilized to calculate the glide-down path. All the guidance information is regarded as the feedback information given to the flight control system to calculate control command. A designed on-vehicle experiment shows that the vision/radar/INS integrated landing guidance system achieves satisfied results.

UAV Flight and Landing Guidance System for Emergency Situations †.

Unmanned aerial vehicles (UAVs) with high mobility can perform various roles such as delivering goods, collecting information, recording videos and more. However, there are many elements in the city that disturb the flight of the UAVs, such as various obstacles and urban canyons which can cause a multi-path effect of GPS signals, which degrades the accuracy of GPS-based localization. In order to empower the safety of the UAVs flying in urban areas, UAVs should be guided to a safe area even in a GPS-denied or network-disconnected environment. Also, UAVs must be able to avoid obstacles while landing in an urban area. For this purpose, we present the UAV detour system for operating UAV in an urban area. The UAV detour system includes a highly reliable laser guidance system to guide the UAVs to a point where they can land, and optical flow magnitude map to avoid obstacles for a safe landing.

A visual/inertial integrated landing guidance method for UAV landing on the ship

This paper presents a visual/inertial integrated guidance method for UAV shipboard landing. The airborne vision system is utilized to track infrared cooperated targets on the ship and output their center coordinates in the image. Meanwhile, the attitude information of the UAV is obtained from airborne Inertial Measurement Unit (IMU). Extended Kalman Filter (EKF) is chosen to fuse the visual and inertial information. The UAV's position, attitude, and velocity relative to the runway and the ship motion information are estimated. The ship motion information is utilized to predict the position of the intended landing point at the touchdown moment through the Autoregressive algorithm. And the motion information of the UAV is used to calculate the deviation from the intended landing path. All the information is delivered to the flight control system to calculate control command. Simulation shows that the visual/inertial integrated landing guidance system achieves satisfied estimation and prediction results.

Autonomous Landing of a Fixed Wing UAV with a Ground-based Visual Guidance System

Fixed wing UAV autonomous landing guidance system needs high precision, fast tracking speed. This paper designs and built a set of Ground-based visual guidance system, which first introduces the visual landing guidance system principle, composition, analysis of the mathematical model and error analysis of the system; The Adaboost algorithm is applied to the recognition of UAV, where UAV samples and non-UAV are chosen for training cascade classifie. After the recognition of UAV, the UAV tracking system based on vision is designed. Finally, the reliability, tracking speed and precision of the system are verified by field experiments. The experimental results show that the designed landing guidance system could meet the requirements of the precise autonomous landing of a fixed wing UAV.

Guidance Summary and Assessment of the Chang’e-3 Powered Descent and Landing

On 14 December 2013, Chang’e-3 successfully touched down on the surface of the moon, setting off its roaming exploration activities. Before this significant step, years of design, development, and testing of the Chang’e-3 powered descent and landing guidance, navigation, and control system were conducted to prepare for the most challenging robotic spacecraft landing endeavor attempted on the moon to date. In this paper, the mission and system design of Chang’e-3 are first described. Then, the guidance algorithms of powered descent and soft landing are summarized and assessed in detail. The powered descent and landing guidance technologies developed for Chang’e-3, including autonomous hazard detection and avoidance, lay the critical foundation for future lunar pinpoint soft-landing missions.

光电着舰引导系统的视轴稳定

To increase line-of-sight (LOS) tracking and pointing accuracy of an Optic-Electro (O-E) landing guidance system, this work explores how to isolate the LOS tracking and pointing of a O-E theodolite from the carrier motion disturbance. A carrier-based O-E theodolite model was established with various disturbance factors introduced. Three kinds of controllers, Lead-lag, LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) and H were designed to improve the stability and performance of the system. The Kalman filter and H weighting matrix were investigated in detail. Then, the controllers were emulated in Matlab and verified on a swing bench. The compared experiments for the three kinds of controllers on time domain, frequency response and stability were performed. Obtained results show that both LQG/LTR and H controllers can satisfy the design specifications, and their decoupling effects are as deep as 50 dB, which can ensure precise tracking and pointing performance of LOSs in O-E landing guidance systems.

Airborne Integrated Vision/Inertial Navigation System for Landing on Aircraft Carrier

It is a very difficult task to land on aircraft carrier, because of limits of the carrier runway during rough sea. In this article, a new algorithm of aircraft carrier landing is proposed utilizing airborne infrared camera/inertial integrated system, which can provide the relative positions and orientation of the aircraft with respect to the carrier so as to help aircrafts semi-auto or auto landing. The mathematic relationship between guidance parameters and imaging information was modeled, and then the relative position and attitude information between the carrier and the aircraft were estimated through Newton iteration method. From that information, the pitching, rolling and heave movement of the carrier were estimated and compensated, so the touchdown point could be predicted and provided to the pilot so as to control aircraft landing. On the ground of the theoretic research, the field verification tests were carried out, which adopted the minification scheme to simulate the process of aircraft carrier landing. In the experiments, the runway simulator simulated the motion of the carrier runway and the land vehicle was used as the aircraft. The results verify the landing guidance system scheme is feasible and effective, and lay the technical foundation for the flight test, improving its safety.

Displacement motion prediction of a landing deck for recovery operations of rotary UAVs

This paper proposes a practical prediction procedure for vertical displacement of a Rotarywing Unmanned Aerial Vehicle (RUAV) landing deck in the presence of stochastic sea state disturbances. A proper time series model tending to capture characteristics of the dynamic relationship between an observer and a landing deck is constructed, with model orders determined by a novel principle based on Bayes Information Criterion (BIC) and coefficients identified using the Forgetting Factor Recursive Least Square (FFRLS) method. In addition, a fast-converging online multi-step predictor is developed, which can be implemented more rapidly than the Auto-Regressive (AR) predictor as it requires less memory allocations when updating coefficients. Simulation results demonstrate that the proposed prediction approach exhibits satisfactory prediction performance, making it suitable for integration into ship-helicopter approach and landing guidance systems in consideration of computational capacity of the flight computer.

Monotonous Trend Estimation of Deck Displacement for Automatic Landing of Rotorcraft UAVs

This paper presents a novel and practical procedure for estimating the mean deck height to assist in automatic landing operations of a Rotorcraft Unmanned Aerial Vehicle (RUAV) in harsh sea environments. A modified Prony Analysis (PA) procedure is outlined to deal with real-time observations of deck displacement, which involves developing an appropriate dynamic model to approach real deck motion with parameters identified through implementing the Forgetting Factor Recursive Least Square (FFRLS) method. The model order is specified using a proper order-selection criterion based on minimizing the summation of accumulated estimation errors. In addition, a feasible threshold criterion is proposed to separate the dominant components of deck displacement, which results in an accurate instantaneous estimation of the mean deck position. Simulation results demonstrate that the proposed recursive procedure exhibits satisfactory estimation performance when applied to real-time deck displacement measurements, making it well suited for integration into ship-RUAV approach and landing guidance systems.

Ship Motion Prediction for Maritime Flight Operations

This paper presents a novel and feasible prediction procedure for ship motion in the presence of uncertain tendency of ship motion dynamic variations and stochastic sea state disturbances. An appropriate model aiming to feature the characteristics of the dynamic relationship between an observer and a ship deck is constructed, from which an initial algorithm is implemented. The optimal system order based on Bayes Information Criterion (BIC) is derived, resulting in the development of an accurate adaptive multi-step predictor for estimation of ship motion dynamics. Simulation results demonstrate that the proposed prediction approach substantially reduces the model complexity and exhibits excellent prediction performance, making it suitable for integration into ship-helicopter approaches and landing guidance systems.

Ecological Approach to Support Pilot Terrain Awareness After Total Engine Failure

Terrain awareness enhancing avionics, such as Synthetic Vision Systems and the Enhanced Ground Proximity Warning System, have been developed to reduce the number of controlled flight into terrain accidents. The protection these systems offer, however, is far from optimal. Synthetic Vision Systems only provide pilots with perceptual data, and leave all cognition and interpretation of data to the pilot. With Enhanced Ground Proximity Warning Systems the opposite is true. Here, pilots are only confronted with compelling advisories and commands without the underlying data and rationale. This paper presents a display system, the Emergency Landing Guidance System, that visualizes the functional of surrounding terrain, adopting an ecological interface design approach. The potential benefits of this approach are demonstrated with the case of locating and approaching a suitable landing area after sudden complete engine failure. To evaluate the effect of the new display on pilot terrain awareness, an experiment was conducted in a fixed-base flight simulator. Results show that the new display supports pilot terrain awareness much better than present terrain avoidance systems, i.e., pilots better understand the meaning of the terrain in relation to their goals and constraints. However, pilots also operated more closely to the limits of performance, thereby negatively affecting the metrics for safety.