Mobile Inspection Robot Research Articles

Design of intelligent controller for obstacle avoidance and navigation of electric patrol mobile robot based on PLC

Currently, the obstacle avoidance control of patrol robots based on intelligent vision lacks professional controller module assistance. Therefore, this paper proposes a design method of intelligent controller for obstacle avoidance and navigation of electrical inspection mobile robot based on PLC control. The controller designs a laser range finder to determine the required position of electrical patrol inspection. Use PLC as the core controller, and combine sensors, actuators, communication module and PLC selection module in the process of hardware design to achieve autonomous navigation and obstacle avoidance functions of the robot. Then design the software including the PLC compiler system and the virtual machine module. Based on the above steps, design the control module of obstacle avoidance navigation, which realizes the key link of robot autonomous navigation. The test results show that the controller can successfully avoid obstacles, improve the efficiency and quality of inspection, and achieve accurate and fast obstacle avoidance navigation for the electrical inspection mobile robot.

Advanced Image Analytics for Mobile Robot-Based Condition Monitoring in Hazardous Environments: A Comprehensive Thermal Defect Processing Framework.

In hazardous environments like mining sites, mobile inspection robots play a crucial role in condition monitoring (CM) tasks, particularly by collecting various kinds of data, such as images. However, the sheer volume of collected image samples and existing noise pose challenges in processing and visualizing thermal anomalies. Recognizing these challenges, our study addresses the limitations of industrial big data analytics for mobile robot-generated image data. We present a novel, fully integrated approach involving a dimension reduction procedure. This includes a semantic segmentation technique utilizing the pre-trained VGG16 CNN architecture for feature selection, followed by random forest (RF) and extreme gradient boosting (XGBoost) classifiers for the prediction of the pixel class labels. We also explore unsupervised learning using the PCA-K-means method for dimension reduction and classification of unlabeled thermal defects based on anomaly severity. Our comprehensive methodology aims to efficiently handle image-based CM tasks in hazardous environments. To validate its practicality, we applied our approach in a real-world scenario, and the results confirm its robust performance in processing and visualizing thermal data collected by mobile inspection robots. This affirms the effectiveness of our methodology in enhancing the overall performance of CM processes.

Design and Development of a Manual Controlled Mobile Robot for Inspection of Cracks in Storm Sewer Using Machine Learning

Design and Development of a Manual Controlled Mobile Robot for Inspection of Cracks in Storm Sewer Using Machine Learning

Multimodal immersive digital twin platform for cyber–physical robot fleets in nuclear environments

AbstractThe nuclear energy sector can benefit from mobile robots for remote inspection and handling, reducing human exposure to radiation. Advances in cyber–physical systems have improved robotic platforms in this sector through digital twin (DT) technology. DTs enhance situational awareness for robot operators, crucial for safety in the nuclear energy sector, and their value is anticipated to increase with the growing complexity of cyber–physical systems. The primary motivation of this work is to rapidly develop and evaluate a robot fleet interface that accounts for these benefits in the context of nuclear environments. Here, we introduce a multimodal immersive DT platform for cyber–physical robot fleets based on the ROS‐Unity 3D framework. The system design enables fleet monitoring and management by integrating building information models, mission parameters, robot sensor data, and multimodal user interaction through traditional and virtual reality interfaces. A modified heuristic evaluation approach, which accounts for the positive and negative aspects of the interface, was introduced to accelerate the iterative design process of our DT platform. Robot operators from leading nuclear research institutions (Sellafield Ltd. and the Japan Atomic Energy Agency) performed a simulated robot inspection mission while providing valuable insights into the design elements of the cyber–physical system. The three usability themes that emerged and inspired our design recommendations for future developers include increasing the interface's flexibility, considering each robot's individuality, and adapting the platform to expand sensor visualization capabilities.

Porcospino, spined single-track mobile robot for inspection of narrow spaces

AbstractThis paper discusses the design and the experimental tests on Porcospino, a bio-inspired single-track mobile robot for inspection of unstructured environments characterized by narrow spaces. It is an evolution of SnakeTrack, a single-track robot with steering capabilities; differently from SnakeTrack, the track modules of Porcospino are characterized by elastic spines, which improve traction on uneven and irregular terrains. The main body is a vertebral column, comprising a series of vertebrae connected by compliant joints and two end modules. Each end module carries two sprockets, sharing a common actuator, to drive the single peripherical track. Moreover, each end module hosts an actuator for track steering. The remaining mobilities of the vertebral column allow it to cope passively with the terrain profile, to enhance traction. The control unit, batteries, drivers, and environmental sensors are placed along the vertebral column. Both the end modules are equipped with a camera for intermittent vision, which is possible thanks to openings realized on the track modules. The experimental campaign on the first Porcospino prototype is discussed, highlighting the differences with its earlier version.

Rotation speed assessment for idlers in belt conveyors using image analysis

Monitoring and diagnostics of elements of the belt conveyor is a challenging task. One of the hardest aspects is dealing with objects such as rolling idlers that support the belt. They are distributed along the entire length of a conveyor, and their amount can easily reach thousands. In the ideal case, every idler should undergo in-situ monitoring, however, this is impractical. Hence, it is proposed to use remote sensing to acquire knowledge about some aspects of their condition. In particular, the authors propose to measure the rotational speed of the idler based on short video recordings. This data could be captured by mobile inspection robots, such as UAVs or UGVs, or even manually. Detecting the fact that the idler rotates with improper speed (lower than nominal), could indicate a developing fault of the internal bearing. An idler that rotates slower than it should also create additional friction between itself and the belt. This friction can increase the overall operational resistances, and even cause fire due to increased temperature. In this paper, the authors present a simple method for establishing the rotational speed of the idler based on video data analysis.

A Model-Free Kullback–Leibler Divergence Filter for Anomaly Detection in Noisy Data Series

Abstract We propose a Kullback–Leibler divergence (KLD) filter to extract anomalies within data series generated by a broad class of proximity sensors, along with the anomaly locations and their relative sizes. The technique applies to devices commonly used in engineering practice, such as those mounted on mobile robots for nondestructive inspection of hazardous or other environments that may not be directly accessible to humans. The raw data generated by this class of sensors can be challenging to analyze due to the prevalence of noise over the signal content. The proposed filter is built to detect the difference of information content between data series collected by the sensor and baseline data series. It is applicable in a model-based or model-free context. The performance of the KLD filter is validated in an industrial-norm setup and benchmarked against a peer industrially adopted algorithm.

Autonomous control for miniaturized mobile robots in unknown pipe networks.

Despite recent advances in robotic technology, sewer pipe inspection is still limited to conventional approaches that use cable-tethered robots. Such commercially available tethered robots lack autonomy, and their operation must be manually controlled via their tethered cables. Consequently, they can only travel to a certain distance in pipe, cannot access small-diameter pipes, and their deployment incurs high costs for highly skilled operators. In this paper, we introduce a miniaturised mobile robot for pipe inspection. We present an autonomous control strategy for this robot that is effective, stable, and requires only low-computational resources. The robots used here can access pipes as small as 75 mm in diameter. Due to their small size, low carrying capacity, and limited battery supply, our robots can only carry simple sensors, a small processor, and miniature wheel-legs for locomotion. Yet, our control method is able to compensate for these limitations. We demonstrate fully autonomous robot mobility in a sewer pipe network, without any visual aid or power-hungry image processing. The control algorithm allows the robot to correctly recognise each local network configuration, and to make appropriate decisions accordingly. The control strategy was tested using the physical micro robot in a laboratory pipe network. In both simulation and experiment, the robot autonomously and exhaustively explored an unknown pipe network without missing any pipe section while avoiding obstacles. This is a significant advance towards fully autonomous inspection robot systems for sewer pipe networks.

Acoustic-based diagnostics of belt conveyor idlers in real life mining conditions by mobile inspection robot

Acoustic-based diagnostics of belt conveyor idlers in real life mining conditions by mobile inspection robot

Measurement of idlers rotation speed in belt conveyors based on image data analysis for diagnostic purposes

It is a challenge for mining enterprises to diagnose the belt conveyors, which length can be tens of kilometres and the number of idlers reaches several thousand. All of them require inspection, which is infeasible to perform using monitoring sensors, such as accelerometers. The authors proposed a novel method for the rotational speed measurement of idlers based on image data analysis. The relation is assumed of the rotation speed decrease due to internal defects. The procedure of visual data processing is verified on the real conveyor idlers. The remote sensing method can be applied in mobile inspection robots such as UAVs or UGVs as well as for manual camera recordings. The accuracy of the proposed method is 0.13-0.67% error depending on the speed range, which is provided by the standard sampling rates (30-60 FPS) and video resolution (1280 x 720 px). Recommendations are formulated for method implementation in practice.

Mobile Wall-Climbing Robot for NDT inspection of vertical concrete structures

Concrete structures, such as bridges or viaducts, play an important role in global road infrastructure. These types of structures are relatively expensive to build and they are susceptible to outer external influences, which in time deteriorate and lead to the reduction of their structural resistance. To reduce this effect, regular inspection is needed, which is often done manually by using specialized equipment to reach certain parts of bridges and viaducts. This process is both expensive and dangerous for the inspectors to conduct. Within the research project ASAP (Autonomous System for Assessment and Prediction of Infrastructure Integrity) in order to overcome these challenges, we have developed a prototype of a wall-climbing robot (WCR) for nondestructive testing (NDT). In this paper, different iterations of the developed WCR prototypes are presented. In four consecutive prototype designs, we have evaluated and upgraded the adhesion and locomotion system. Finally, a fifth prototype that carries the NDT equipment is presented. The final version of the WCR is equipped with robust and flexible adhesion that enables the robot to adhere to different types of surfaces. We have also addressed the challenges of integrating NDT equipment into the robot. To successfully conduct an inspection, besides the WCR, a safety system, control, and power systems are needed, which are further presented and discussed.

Visual navigation system for generator stator wedge inspection mobile robot

Stator wedge tightness inspection is one of the most important periodic inspections carried out on required for large-capacity generators. The traditional wedge tightness inspection method enforces inspectors to enter the narrow and uncomfortable inner space of a stator. As an alternative, a wedge tightness inspection mobile robot is developed. This robot has a robotic arm with a wedge tightness test module. A visual navigation system using two cameras is proposed. The proposed system controls the driving of the robot in a stator by using line detection of the bottom view camera image. The system also detects wedges and assigns a location number to them by using the inspection view camera image and an object detector based on a convolutional neural network. The detected wedges are tracked using robot motion to assign location numbers to the new wedges. The inspection points are then determined using the length and position of the detected wedges. The experimental results conducted on the stator testbed demonstrate the potential applicability of the proposed system.

Construction of 2D relative positioning accuracy evaluation experimental system for mobile robots for infrastructure inspection

Construction of 2D relative positioning accuracy evaluation experimental system for mobile robots for infrastructure inspection

Inspection Mobile Robot’s Control System with Remote IoT-based Data Transmission

The article presents the main stages of the development of remote control system for the inspection mobile robot operating on inclined ferromagnetic surfaces. The mobile robot remains on the surface and moves along working areas using separate clamping permanent magnets and caterpillars. The focus is on the control system’s architecture and remote data transmission based on Internet of Things technologies. Features of non-expensive Arduino Uno and WeMos D1 R2 mini microcontrolled development boards, cloud service Blynk, as well as multi-tab Android application interactions are revealed at the inspection mobile robot movement on the inclined surface. Experimental results of the proposed system show a good compatibility of chosen hardware, user-friendly human-machine interface and high mobility for future research of modern control algorithms at Internet of Things approach implementation for the extreme robotics.

Toward A Mobile Robot for Vibration Control and Inspection of Power Lines

Abstract As power demand across communities increases, focus has been given to the maintenance of power lines against harsh environments such as wind-induced vibration (WIV). Inspection robots and fixed vibration absorbers (FVAs) are the current solutions. However, both solutions are currently facing many challenges. Inspection robots are limited by their size and considerable power demand, while FVAs are narrowband and unable to adapt to changing wind characteristics and thus are unable to reposition themselves at the antinodes of the vibrating loop. In view of these shortcomings, we propose a mobile damping robot (MDR) that integrates inspection robots mobility and FVAs WIV vibration control to help maintain power lines. In this effort, we model the conductor and the MDR by using Hamilton’s principle, and we consider the two-way nonlinear interaction between the MDR and the cable. The MDR is driven by a proportional-derivative (PD) controller to the optimal vibration location (antinodes) as the wind characteristics vary. The numerical simulations suggest that the MDR outperforms FVAs for vibration mitigation. Furthermore, the key parameters that influence the performance of the MDR are identified through a parametric study. The findings could setup a platform to design a prototype and experimentally evaluate the performance of the MDR.

Functional Design of a Hybrid Leg-Wheel-Track Ground Mobile Robot

This paper presents the conceptual and functional design of a novel hybrid leg-wheel-track ground mobile robot for surveillance and inspection, named WheTLHLoc (Wheel-Track-Leg Hybrid Locomotion). The aim of the work is the development of a general-purpose platform capable of combining tracked locomotion on irregular and yielding terrains, wheeled locomotion with high energy efficiency on flat and compact grounds, and stair climbing/descent ability. The architecture of the hybrid locomotion system is firstly outlined, then the validation of its stair climbing maneuver capabilities by means of multibody simulation is presented. The embodiment design and the internal mechanical layout are then discussed.

Hierarchical fuzzy obstacle avoidance control of omnidirectional mobile robot for substation inspection

There are some limitations in the practical application of robot obstacle avoidance control methods. In order to realize the high-speed planning and obstacle avoidance processing of mobile robot, the path model, inspection route and path obstacles of the robot must be fully considered. Through feature extraction, the reasonable planning of substation inspection obstacle avoidance route is realized, and the control quantity set satisfying substation inspection is given. The hierarchical fuzzy obstacle avoidance control method of mobile robot is realized by using the optimal control set design. The simulation results show that the control method can solve various complex problems when the robot contour collides with obstacles, and can realize safe and fast control. The flexibility and robustness of obstacle avoidance are improved, and the motion state and speed of obstacles are also improved.

Accuracy Evaluation of Selected Mobile Inspection Robot Localization Techniques in a GNSS-Denied Environment.

Locating an inspection robot is an essential task for inspection missions and spatial data acquisition. Giving a spatial reference to measurements, especially those concerning environmental parameters, e.g., gas concentrations may make them more valuable by enabling more insightful analyses. Thus, an accurate estimation of sensor position and orientation is a significant topic in mobile measurement systems used in robotics, remote sensing, or autonomous vehicles. Those systems often work in urban or underground conditions, which are lowering or disabling the possibility of using Global Navigation Satellite Systems (GNSS) for this purpose. Alternative solutions vary significantly in sensor configuration requirements, positioning accuracy, and computational complexity. The selection of the optimal solution is difficult. The focus here is put on the assessment, using the criterion of the positioning accuracy of the mobile robot with no use of GNSS signals. Automated geodetic surveying equipment is utilized for acquiring precise ground truth data of the robot’s movement. The results obtained, with the use of several methods, compared: Wheel odometry, inertial measurement-based dead-reckoning, visual odometry, and trilateration of ultra-wideband signals. The suitability, pros, and cons of each method are discussed in the context of their application in autonomous robotic systems, operating in an underground mine environment.

Mechanism design of a small mobile robot for inspection of underground cables-in-pipe

With the rapid growth of urban power load, underground cables-in-pipe is increasingly used in urban power transmission. The operation status inspection of underground cables-in-pipe is very important to guarantee the safety of power transmission. At present, mostly, the inspection of the underground cables-in-pipe is implemented by workers after cutting the power supply. Cutting power supply will cause economic loss. In addition, the workers cannot step into the narrow pipes, which lead to low inspection efficiency and the high omission factor. In order to solve the above problems, this paper proposes a novel mechanism of a small mobile robot for underground cables-in-pipe inspection. In the pipes where cables have been laid, the remaining space is narrow and irregular. Through the unique compact design of the robot mechanism, we make the robot able to run smoothly in the pipes. In this paper, we firstly establish the remaining space model of the cable-laid pipes. Then design the mechanism model of each part of the robot. After that, we determine the specific structural parameters. Finally, we carry out the feasibility analysis of the whole robot mechanism. The results of the analysis indicate that, the designed robot mechanism can move smoothly in underground cable pipes.

Robust Adaptive Terminal Sliding Mode Control of an Omnidirectional Mobile Robot for Aircraft Skin Inspection

In this paper, an adaptive terminal sliding mode control scheme for an omnidirectional mobile robot is proposed as a robust solution to the trajectory tracking control problem. The omnidirectional mobile robot has a double-frame structure, which adsorbes on the aircraft surface by suction cups. The major difficulties lie in the existence of nonholonomic constraints, system uncertainty and external disturbance. To overcome these difficulties, the kinematic model is established, the dynamic model is derived by using Lagrange method. Then, a robust adaptive terminal sliding mode (RATSM) control scheme is proposed to solve the problem of state stabilization and trajectory tracking. In order to enhance the robustness of the system, an adaptive online estimation law is designed to overcome the total uncertainty. Subsequently, the asymptotic stability of the system without total uncertainty is proved with basis on Lyapunov theory, and the system considering total uncertainty can converge to the domain containing the origin. Simulation results are given to show the verification and validation of the proposed control scheme.