Ground Mobile Robots Research Articles

Design and Kinematic Analysis of a Wall-climbing Robot for Bridge appearance Inspection

In order to solve the maneuverability and safety of large bridge appearance inspection, a new type of hexapod wall-climbing robot is designed. As an important branch of mobile robot field, the organic combination of ground mobile robot technology and adsorption technology greatly expands the application range of robot. This paper introduces the mechanical structure of two self-designed legged wall-climbing robots, puts forward four problems on the quadruped robot and improves them on the hexapod robot. At the same time, in order to control the hexapod wall-climbing robot, the kinematics model of the hexapod wall-climbing robot must be established, and on this basis, the forward and inverse kinematics equations of the robot should be solved. The research results show that the two new robots meet the requirements of reliable adsorption and flexible movement, and have large application scenarios. The forward and inverse kinematics solved by the established kinematics model is proved to be effective by experiments.

Designing human–system cooperation in industry 4.0 with cognitive work analysis: a first evaluation

One objective of Industry 4.0 is to reach a better system performance as well as to have a better consideration of humans. This would be done by benefiting from knowledge and experience of humans, and balancing in a reactive way some complex or complicated tasks with intelligent systems. Several studies already dealt with such an objective, but few are done at a methodological level, which forbids, for example, the correct evaluation of design choices in terms of human awareness of the situation or mental workload when designing intelligent manufacturing systems integrating the human. Indeed, increasing the intelligence and autonomy of industrial systems and their composing entities (resources, products, robots…), as fostered by Industry 4.0, increases their overall complexity. This modification reduces the ability to understand the behaviors of these systems, and leads to the difficulty for humans not only to elaborate alternative decisions when required, but also to make effective decisions and understand their consequences. This paper evaluates such a design methodology, the Cognitive Work Analysis (CWA), and its applicability when designing an assistance system to support Human in the control of Intelligent Manufacturing System in Industry 4.0. Among several functions identified through the application of CWA, the assistant system might have to integrate a digital twin of the intelligent manufacturing system. The evaluation of the methodology through the one of the designed assistant systems is done using a micro-world, which is an intelligent manufacturing cell composed of intelligent mobile ground robots, products, and static production robots interacting together and with a human supervisor in charge of the reaching of several time-based and energy-based performances indicators. The assistant system embeds a digital twin of the intelligent manufacturing system. Twenty-three participants took part in experiments to evaluate the designed assistance system. First results show that the assistance system enables participants to have a correct awareness of the situation and a correct evaluation of their alternative decisions, while their mental workload is managed and expected production performances are reached. This paper contains an analysis of these experiments and points out some limits of the CWA method in the context of Industry 4.0, especially the lack of tool enabling to specify clearly the cooperation processes between the supervisor and the intelligent manufacturing system. This paper concludes with potential research avenues, the main one being the potential benefits of coupling CWA with human–machine cooperation principles to fine tune and adapt the cooperation between the human and the intelligent manufacturing system.

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.

Finite-time control of multiagent networks as systems with time transformation and separation principle

In this paper, we study finite-time control of multiagent networks as systems, where they involve floating agents that exchange local information and driver agents that not only exchange local information but also take input and output roles. For this class of multiagent networks, control algorithms are applied to the driver agents based on the measurements collected from them for the purpose of influencing the overall behavior of the resulting system. Specifically, we consider time-critical applications in the control of multiagent networks as systems and propose a finite-time control approach predicated on a recent time transformation method. The proposed method guarantees execution of control algorithms over a prescribed time interval [0,T) with T being a user-defined convergence time based on analysis performed over a stretched, infinite-time interval [0,∞). We analytically show that the resulting system achieves user-defined finite-time convergence regardless of the initial conditions of agents, where we also discuss the separation principle obtained with the proposed method. The presented theoretical contributions are not only illustrated by numerical examples but also experimentally validated using ground mobile robots.

Real-Time Lidar-based Localization of Mobile Ground Robot

Paper discusses modern methods for localization of mobile ground robot in outdoor environment. Special attention is payed to lidar-based methods which allow to do precise simultaneous localization and mapping (SLAM) independently to lighting conditions. Modular approach to lidar-based localization is proposed. It consists of three modules: map reconstructor, map merger and corrector, localization module. As map reconstructor we use 3D Lidar-based Graph SLAM, state-of-the-art method LOAM and its modification with point cloud segmentation techniques A-LeGO-LOAM. As map merger and corrector we apply the technique of interactive map correction for 3D Graph SLAM. For localization module we compare different real-time approaches: NDT scan matching and Localization with scan batch processing. They do not allow to localize the robot with an unknown initial position. To overcome this problem, a stage of global Monte Carlo localization is proposed, which allows to generate a switching condition and a rough initial pose. Matrix of localization convergence speed is introduced to study influence of possible inaccuracies of initial pose estimation to the convergence of real-time localization approach. An important emphasis in the paper is made to the evaluation of the localization quality with relative and absolute metrics. Experimental results are obtained for own data from mobile ground robot ClearPath Husky equipped with Velodyne HDL-32E lidar. Proposed approach to robot localization achieves real-time performance for different hardware platforms in particular single-board computer Nvidia Jetson Xavier. It demonstrates possibility for integration of studied modular localization approach to onboard control systems of autonomous vehicles.

Probabilistic Indoor Positioning and Navigation (PIPN) of Autonomous Ground Vehicle (AGV) Based on Wireless Measurements

Recently, Autonomous Ground Vehicles (AGV) and mobile robots have been rapidly developed in various engineering applications, such as Industry 4.0 factory and smart manufacturing. Indoor navigation was one of the most important tasks for the mobile systems as they were often designed to move from one location to another location autonomously without contacting the surrounding objects along the moving path in a usually dynamic and complex indoor environment. There were two key steps to achieve Simultaneous Localization and Mapping (SLAM). First, indoor positioning of the mobile system based on some measurements was done. The second step was to navigate itself inside the indoor map. This was a very challenging problem because there always existed uncertainties in the measurements. It was desired to estimate the positioning errors and determine a safe moving path with high reliability. This paper presented the methodologies for wireless indoor positioning and navigation of AGV with measurement uncertainties. Two kinds of AGV moving trajectories with various design parameters were simulated: a linear trajectory and a curved one. It was found that both greater number of sensors being used for wireless measurements and greater number of measurement trials for multilateration could effectively improve the accuracy of AGV positioning.

Event Camera Based Real-Time Detection and Tracking of Indoor Ground Robots

This paper presents a real-time method to detect and track multiple mobile ground robots using event cameras. The method uses density-based spatial clustering of applications with noise (DBSCAN) to detect the robots and a single k-dimensional (k-d) tree to accurately keep track of them as they move in an indoor arena. Robust detections and tracks are maintained in the face of event camera noise and lack of events (due to robots moving slowly or stopping). An off-the-shelf RGB camera-based tracking system was used to provide ground truth. Experiments including up to 4 robots are performed to study the effect of i) varying DBSCAN parameters, ii) the event accumulation time, iii) the number of robots in the arena, and iv) the speed of the robots on the detection and tracking performance. The experimental results showed 100% detection and tracking fidelity in the face of event camera noise and robots stopping for tests involving up to 3 robots (and upwards of 93% for 4 robots).

Improved hybrid A* path planning method for spherical mobile robot based on pendulum

This article proposes a modification of hybrid A* method used for navigation of spherical mobile robots with the ability of limited partial lateral movement driven by pendulum. For pendulum-driven spherical robots with nonzero minimal turning radius, our modification helps to find a feasible and achievable path, which can be followed in line with the low time cost. Because of spherical shell shape, the robot is point contact with the ground, showing different kinematic model compared with common ground mobile robots such as differential robot and wheeled car-like robot. Therefore, this article analyzes the kinematic model of spherical robot and proposes a novel method to generate feasible and achievable paths conforming to kinematic constraints, which can be the initial value of future trajectory tracking control and further optimization. A concept of optimal robot’s minimum area for rotation is also proposed to improve search efficiency and ensure the ability of turning to any orientation by moving forward and backward in a finite number of times within limited areas.

УПРАВЛЕНИЕ ДВИЖЕНИЕМ НАЗЕМНОГО МОБИЛЬНОГО РОБОТА ПРИ НАРУШЕНИИ ЦЕЛОСТНОСТИ НАВИГАЦИОННЫХ ДАННЫХ СПУТНИКОВОЙ НАВИГАЦИОННОЙ СИСТЕМЫ

The article discusses the determination of navigational data corruption, which received by the satellite navigation system as well as traffic control of ground mobile robots. It also specifies the movement features of ground robots, which affect the data integrity monitoring. It proposes an algorithm of control to implement the methods of autonomous onboard monitoring of the navigational data integrity. The algorithm is based on the equations of signal correspondence in various parts of the control system. It is designed to determine the inoperability of the satellite navigation system that implies the loss of signal and failure in the navigation problem solution. The algorithm takes into account the non-deterministic nature of moving ground robot with possible stops in the process of following the trajectory. The article considers the implementation variants of algorithm to assess reliability for the control system containing additional sensors of the robot’s displacement and for the hardware-redundant system containing no additional sensors. The results of modeling the movement of a ground mobile robot along an arbitrary trajectory in case of navigational data corruption are presented. The features of algorithm based on the simulation results are described in the article. The authors considered variants of robot control in case of navigational data corruption. The structure of the system and a method for controlling a mobile robot in case of satellite navigation system failures are also proposed. The method is based on the control mode in the system, according to the measured data of the position of the robot in the case of navigational data corruption or otherwise according to the data calculated from the robot model. The implementation of the method makes it possible to avoid significant deviations of the robot from a given trajectory of movement at intervals of signal loss of the satellite navigation system.

A Review on Teleoperation of Mobile Ground Robots: Architecture and Situation Awareness

Currently, the application of mobile ground robots spans a range of fields from surveillance, search and rescue, exploration, agriculture, military among others. In unstructured and dangerous environments such as disaster scene, military fields or chemical spray in agricultural farms, the experience and intelligence of the operator are necessary for making complex decisions beyond the autonomy of the robot. In such cases, teleoperation allow the operator to guide the robot in achieving complex task from a safe location. The effectiveness with which the operator controls the robot depends on, among others, operator’s awareness of the robot’s environment, the quality of communication link, the robustness of robot’s control system and experience of the human operator. Ground mobile robots form the basis of this work since they are applicable in many fields and mostly operate in dynamic environments that require additional guidance from a human operator. This study reviews research work on mobile robot teleoperation systems, and puts more emphasis on the architecture, communication link and situation awareness creation. Moreover, future trend in mobile robot teleoperation is also put forward in this review to give ground for new research work in this field. Based on the sited literature, it is noted that making the operator feel present in the robot’s environment through sufficient visual and force feedback as well as use of good quality network, significantly improve the navigation efficiency and task achievement of mobile ground robots.

Memory‐enhanced cognitive radar for autonomous navigation

This study introduces a cognitive radar system for autonomous robotic navigation and presents results of simulations and experiments. The study focuses on the role of memory within autonomous cognitive radar systems, examining the impact that working memory has on navigation performance. A suitable radar architecture is derived, inspired by basic natural cognitive processes. It is then implemented and tested in laboratory conditions with an appropriate technology demonstrator on-board a ground mobile robot. To the best of the authors’ knowledge, this work presents the first results of an experimentally realised cognitive radar system that explicitly incorporates a short-term memory function for robotic navigation.

From Motions to Emotions: Can the Fundamental Emotions be Expressed in a Robot Swarm?

This paper explores the expressive capabilities of a swarm of miniature mobile robots within the context of inter-robot interactions and their mapping to the so-called fundamental emotions. In particular, we investigate how motion asnd shape descriptors that are psychologically associated with different emotions can be incorporated into different swarm behaviors for the purpose of artistic expositions. Based on these characterizations from social psychology, a set of swarm behaviors is created, where each behavior corresponds to a fundamental emotion. The effectiveness of these behaviors is evaluated in a survey in which the participants are asked to associate different swarm behaviors with the fundamental emotions. The results of the survey show that most of the research participants assigned to each video the emotion intended to be portrayed by design. These results confirm that abstract descriptors associated with the different fundamental emotions in social psychology provide useful motion characterizations that can be effectively transformed into expressive behaviors for a swarm of simple ground mobile robots.

Ultra-Wideband Radio Channel Characteristics for Near-Ground Swarm Robots Communication

Ultra-Wideband (UWB) technology has great potential for the cooperation and navigation among near ground mobile robots in GPS-denied environments. In this paper, an efficient two-segment UWB radio channel model is proposed with considering the multi-path condition in very near-ground environments and different surface roughness. We conducted field measurements to collect channel information, with both transmitter and receiver antennas placed at different heights above the ground: 0cm-20cm. Signal frequency was chosen at 4.3GHz with bandwidth of 1GHz. Three ground coverings were tested in common scenarios: brick, grass and robber fields. The proposed model has enhanced accuracy achieved by careful assessment of dominant propagation mechanisms in each segment, such as diffraction loss due to obstruction of the first Fresnel zone and higher-order waves produced by ground roughness. It is realized that antenna height and distance are the most influential geometric parameters to affect the path loss model. Once the antenna height is known, there exists a breakpoint distance in UWB propagation, which separates two segmentation using the different path-loss mechanism. Different surface types can cause different signal attenuation. Monte Carlo simulations are used to investigate the effects of antenna height, distance, ground surface type on mobile robots swarm communication to find out the antenna height is also a dominant factor on connectivity and the average number of neighbors. Within a certain range, the higher the antenna height and the closer the communication distance, the better the communication performance will usually be. Cramér-Rao lower bound(CRLB) of path loss estimator based on the proposed model is derived to show the relationship between CRLB with height and distance.

Structural and intelligent scheme of navigation system of a ground-based mobile robot for forming a traffic route

At the beginning of Russian studies on the task of creating mobile ground fire robots for use in extreme situations in late 1980, it was justified by the fact that firefighters need protection when dealing with the consequences of accidents in areas with high levels of radioactive pollution. The use of fire robotics was increase because of a large number of technogenic accidents. There was a need for use of fire ground robots, where emergency situations, fire, and technogenic accidents arise because it’s dangerous for the life and health of firefighters and people. Fire mobile ground robot is an automated self-propelled technical device which does given commands of human and other actions without human. People use this robot at the accident on area, where is dangerous for the health of firefighters things are situated like oil, nuclear, chemical objects. Now we are considering a structural and intelligent navigation system of fire mobile ground robot, in which a structure of fire robot must create a good way to the center of ignition, control parameters of motions, track own location for safe navigation and improvement tactical of opportunities of the firefighters. The introduction of a fire mobile ground robotics device is needed for an increase in the tactical capabilities of fire detachments during the extinguishing of the fire. The goal is to the definition of tasks and development structural and intelligent scheme of the navigation system of fire mobile robot for the shortest path to fire and extinguish a fire.

Canopy-Based Monte Carlo Localization in Orchards Using Top-View Imagery

Localization of ground mobile robots in orchards is a complex problem which is yet to be fully addressed. The typical localization approaches are not adjusted to the characteristics of the orchard environment, especially the homogeneous scenery. To alleviate these difficulties, we propose to use top-view images of the orchard acquired in real-time. The top-view observation of the orchard provides a unique signature of every tree formed by the shape of its canopy. This practically changes the homogeneity premise in orchards and paves the way for addressing the kidnapped robot problem. Using computer vision techniques, we build a virtual canopies laser scan around the ground robot which is generated from low-altitude top-view video streams. We apply Monte Carlo Localization on this virtual scan to localize the robot against a high-altitude top-view snapshot image which is used as a map. The suggested approach is examined in numerous offline experiments conducted on data acquired in real orchards and is compared against a typical simulated approach which relies on ground-level trunk observations. The canopy-based approach demonstrated better performance in all measures, including convergence to centimeter-level accuracy.

Slip-Aware Motion Estimation for Off-Road Mobile Robots via Multi-Innovation Unscented Kalman Filter

Benefiting from high mobility and robust mechanical structure, ground mobile robots are widely adopted in the outdoor environment. The mobility of skid-steered mobile robots highly depends on the nonlinear and uncertain interaction between the tire and terrain. This paper introduces an approach to estimate the position, orientation, velocity, and wheel slip for the skid-steered mobile robots navigating on off-road terrains. More specifically, a Multi-Innovation Unscented Kalman Filter (MI-UKF) is developed to fusing different sensors' data. Historical innovations generated along the time sequence are merged into the update process of standard UKF to improve the accuracy of motion estimation. In the proposed estimator, an asymmetric ICR kinematic indicating wheel slip is taken into localization process. A four-wheeled prototype is introduced and three challenging test scenarios are designed. The improvements in orientation and velocity estimation are achieved according to results comparison. In the turning maneuver, the ICRs-based model operates more steady than the traditional wheel slip/skid model.

Communication Constrained Distributed Spatial Field estimation Using Mobile Sensor Networks

Abstract In this paper we address the problem of distributed estimation of spatial fields using mobile sensor networks with communication constraints. These constraints consist of a maximum communication bandwidth which limits the amount of data that can be exchanged between any two nodes of the network at each time instant. An algorithm to select the most significant data to be transferred between neighboring sensor nodes is developed starting from derived analytical error bounds. Moreover, the motion of the network nodes is controlled using a coverage control algorithm with the objective of minimizing the estimation uncertainty of each of the nodes. The resulting communication constrained distributed estimation algorithm is deployed on a team of ground mobile robots in the Robotarium, and its performance is evaluated both in terms of estimation accuracy of a simulated spatial field, and of the amount of data transferred.

Bearing-based formation manoeuvre control of nonholonomic multi-agent systems

ABSTRACTThis paper concerns on the bearing-based leader–follower formation manoeuvre control problem for two- (2D) and three-dimensional (3D) multi-agent systems with nonholonomic constraint. The target formation is defined by relative-bearing measurements, which, for example, can be obtained from onboard cameras. The contributions of this paper are twofold. Firstly, a distributed formation manoeuvre control law is proposed for 2D nonholonomic agents according to the inter-bearing measurement. The multi-agent systems can achieve the desired formation which is defined by the bearings information. The formation manoeuvre can be achieved by steering at least two leaders. Secondly, the control law is nontrivially extended to 3D nonholonomic multi-agents systems. The leader–follower formation tracking problem can also be solved by the proposed proportional-integral control scheme. Simulation results for 2D and 3D nonholonomic multi-agents systems are presented. Experiments that used ground mobile robots verify the effectiveness of the proposed control laws.

ITC: Infused Tangential Curves for Smooth 2D and 3D Navigation of Mobile Robots †

Navigation is an indispensable component of ground and aerial mobile robots. Although there is a plethora of path planning algorithms, most of them generate paths that are not smooth and have angular turns. In many cases, it is not feasible for the robots to execute these sharp turns, and a smooth trajectory is desired. We present ‘ITC: Infused Tangential Curves’ which can generate smooth trajectories for mobile robots. The main characteristics of the proposed ITC algorithm are: (1) The curves are tangential to the path, thus maintaining continuity, (2) The curves are infused in the original global path to smooth out the turns, (3) The straight segments of the global path are kept straight and only the sharp turns are smoothed, (4) Safety is embedded in the ITC trajectories and robots are guaranteed to maintain a safe distance from the obstacles, (5) The curvature of ITC curves can easily be controlled and smooth trajectories can be generated in real-time, (6) The ITC algorithm smooths the global path on a part-by-part basis thus local smoothing at one point does not affect the global path. We compare the proposed ITC algorithm with traditional interpolation based trajectory smoothing algorithms. Results show that, in case of mobile navigation in narrow corridors, ITC paths maintain a safe distance from both walls, and are easy to generate in real-time. We test the algorithm in complex scenarios to generate curves of different curvatures, while maintaining different safety thresholds from obstacles in vicinity. We mathematically discuss smooth trajectory generation for both 2D navigation of ground robots, and 3D navigation of aerial robots. We also test the algorithm in real environments with actual robots in a complex scenario of multi-robot collision avoidance. Results show that the ITC algorithm can be generated quickly and is suitable for real-world scenarios of collision avoidance in narrow corridors.

Coordinated Bayesian-Based Bioinspired Plume Source Term Estimation and Source Seeking for Mobile Robots

A new nonparametric Bayesian-based motion planning algorithm for autonomous plume source term estimation (STE) and source seeking (SS) is presented in this paper. The algorithm is designed for mobile robots equipped with gas concentration sensors. Specifically, robots coordinate and utilize a Gaussian-plume likelihood model in a Bayesian-based STE process, then they simultaneously search for and navigate toward the source through model based, bioinspired SS methods such as biased-random-walk and surge-casting. Compared with the state-of-the-art Bayesian- and sensor-based STE/SS motion planners, the strategy described takes advantage of coordination between multiple robots and the estimated plume model for faster and more robust SS, rather than rely on direct or filtered sensor measurements. A set of Monte Carlo simulation studies are conducted to compare the performance between the uncoordinated and coordinated algorithms for different robot team sizes and starting conditions. Additionally, the algorithms are validated experimentally through a laboratory-safe, realistic humid-air plume that behaves similar to a gas plume, to test STE and SS using mobile ground robots equipped with humidity sensors. Simulation and experimental results show consistently that the algorithm involving coordination outperforms traditional bioinspired SS algorithms and it is approximately twice as fast as the uncoordinated case. Finally, the plume source is distorted to study the algorithm's limitations and impact on STE and SS, where results show that even for distorted plumes, useful source localization information can be obtained.