Slide-Down Prevention for Wheeled Mobile Robots on Slopes

Wheeled mobile robots on inclined terrain can slide down due to loss of traction and gravity. This type of instability, which is different from tip-over, can provoke uncontrolled motion or get the vehicle stuck. This paper proposes slide-down prevention by real-time computation of a straightforward stability margin for a given ground-wheel friction coefficient. This margin is applied to the case study of Lazaro, a hybrid skid-steer mobile robot with caster-leg mechanism that allows tests with four or five wheel contact points. Experimental results for both ADAMS simulations and the actual vehicle demonstrate the effectiveness of the proposed approach.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Suspension effect in tip-over stability and steerability of robots moving on terrain discontinuities

[ES] En este artículo se estudia el efecto que produce el sistema de suspensión sobre la estabilidad al vuelco y la capacidad de direccionamiento en un robot móvil Skid Steer, cuando este se enfrenta a distintas discontinuidades del terreno: descenso (frontal y lateral) y ascenso sobre escalones, además del desplazamiento sobre zanjas. Específicamente, se estudió el instante cuando se generan cargas de impacto producto del movimiento del robot sobre la irregularidad del terreno. En cada caso se hizo un análisis correlacional del efecto sobre la estabilidad al vuelco y el direccionamiento (cuantificadas con métricas fundamentadas en las fuerzas de reacción de las ruedas con el suelo), al variar cuatro parámetros que definen el sistema de suspensión: constante de rigidez en los resortes, constante de amortiguamiento en los amortiguadores y las constantes de rigidez y amortiguamiento en las ruedas. Por último se estimó para cada caso, qué magnitudes deberían adquirir estos parámetros para garantizar una mejor estabilidad y direccionamiento del robot.[EN] This article studies the effect produced by the suspension system in tip-over stability and steerability of a Skid Steer mobile robot, when it faces different terrain discontinuities: descent (front and side) and ascent on steps, plus displacement over ditches. Specifically, the moment was studied when impact loads producted by the robot's movement on the irregularity of the terrain are generated. In each case, a correlational analysis was made about the effect in tip-over stability and steerability (quantified with metrics based on the reaction forces of the wheels with the ground), by varying four parameters that define the suspension system: stiffness constant in the springs, damping constant in the dampers and the stiffness and damping constants in the wheels. Finally, it was estimated for each case, what magnitudes these parameters should acquire to ensure better stability and steerability of robot.Este trabajo ha sido realizado parcialmente gracias al apoyo del Decanato de Investigación de la Universidad Nacional Experimental del Táchira bajo los proyectos 01-025-2016 y 01-008-2018.García, JM.; Valero, A.; Bohórquez, A. (2020). Efecto de la suspensión en la estabilidad al vuelco y direccionamiento de robots moviéndose sobre discontinuidades de terreno. Revista Iberoamericana de Automática e Informática industrial. 17(2):202-214. https://doi.org/10.4995/riai.2020.12308OJS202214172Abo-Shanab, R., & Sepehri, N., 2005. Tip-over stability of manipulator-like mobile hydraulic machines. Journal of Dynamic Systems, Measurement and Control , 127 (2), 295-301. https://doi.org/10.1115/1.1898239Bluethmann, B., Herrera, E., Hulse, A., Figuered, J., Junkin, L., Markee, M., y otros., 2010. An active suspension system for lunar crew mobility. 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Proc. 23rd Mediterranean Conference on Control and Automation, (págs. 267-272). Torremolinos, Spain. https://doi.org/10.1109/MED.2015.7158761García, J. M., Medina, I., Cerezo, A. G., & Linares, A., 2015a. Improving the static stability of a mobile manipulator using its end effector in contact with the ground. IEEE Latin American Transactions , 13 (10), 3228-3234. https://doi.org/10.1109/TLA.2015.7387226García, J., Medina, I., Martínez, J., García-Cerezo, A., Linares, A., & Porras, C., 2017a. Lázaro: robot móvil dotado de brazo para contacto con el suelo. Revista Iberoamericana de Automática e Informática industrial , 14 (1), 174-183. https://doi.org/10.1016/j.riai.2016.09.012Goga, V., & Kl'úcik, M., 2012. Optimization of vehicle suspension parameters with use of evolutionary computation. Procedia Engineering , 48, 174-179. https://doi.org/10.1016/j.proeng.2012.09.502Hurel, J., Mandow, A., & García-Cerezo, A., 2013. Los sistemas de suspensión activa y semiactiva: una revisión. Revista iberoamericana de automática e informática , 10 (2), 121-132. https://doi.org/10.1016/j.riai.2013.03.002Kang, S., Lee, W., Kim, M., & Shin, K., 2005. Robhaz-rescue: Rough-terrain negotiable teleoperated mobile robot for rescue mission. IEEE International Workshop on Safety, Security and Rescue Robotics, (págs. 105-110). Kobe.Lei, X., Zhang, G., Li, S., Qian, H., & Xu, Y., 2017. Dual-spring AGV shock absorption system design: Dynamic analysis and simulations. IEEE International Conference on Robotics and Biomimetics (ROBIO), (págs. 1-7). Macau. https://doi.org/10.1109/ROBIO.2017.8324559Li, B., Ma, S., Liu, J., Wang, M., Liu, T., & Wang, Y., 2009. Amoeba-I: a shape-shifting modular robot for urban search and rescue. Advanced Robotics , 23 (9), 1057-1083. https://doi.org/10.1163/156855309X452485Liu, Y., Meng, X., & Zhang, M., 2008. Research on mobile manipulator tip-over stability and compensation. 8th WSEAS International Conference on Robotics, control and Manufacturing Technology, (págs. 114-120). Hangzhou.Luo, Z., Shang, J., Wei, G., & Ren, L., 2018. Module-based structure design of wheeled mobile robot. Mechanical Sciences , 9 (1), 103-121. https://doi.org/10.5194/ms-9-103-2018Mihon, L., & Lontiș, N., 2019. Modeling and analysis of a vehicle suspension. En N. Burnete, & B. Varga (Ed.), Proceedings of the 4th International Congress of Automotive and Transport Engineering (AMMA 2018), (págs. 113-121). https://doi.org/10.1007/978-3-319-94409-8_14Moosavian, A., Alipour, K., & Bahramzadeh, Y., 2007. Dynamics modeling and tip-over stability of suspended wheeled mobile robots with multiple arms. IEEE/RSJ International Conference on Intelligent Robots and Systems, (págs. 1210-1215). San Diego. https://doi.org/10.1109/IROS.2007.4398999Reid, W., Pérez-Grau, F., Göktogan, A., & Sukkarieh, S., 2016. Actively articulated suspension for a wheel-on-leg rover operating on a martian analog surface. IEEE International Conference on Robotics and Automation (ICRA), (págs. 5596-5602). Stockholm. https://doi.org/10.1109/ICRA.2016.7487777Sert, E., & Boyraz, P., 2017. Optimization of suspension system and sensitivity analysis for improvement of stability in a midsize heavy vehicle. Engineering Science and Technology, an International Journal , 20, 997-1012. https://doi.org/10.1016/j.jestch.2017.03.007Suresh, A., Ajithkumar, N., Kalathil, S., Simon, A., Unnikrishnan, V., Mathew, D., y otros., 2017. An advanced spider-like rocker-bogie suspension system for mars exploration rovers. En J. Kim, F. Karray, P. Sincak, & G. Myung (Ed.), Robot Intelligence Technology and Applications 4. Advances in Intelligent Systems and Computing. 447, págs. 423-447. Springer. https://doi.org/10.1007/978-3-319-31293-4_34Yang, L., Cai, B., Zhang, R., Li, K., & Wang, R., 2018. 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Design and Development of an Automated Mobile Manipulator for Industrial Applications

This thesis presents the modeling, control and coordination of an automated mobile manipulator. A mobile manipulator in this investigation consists of a robotic manipulator and a mobile platform resulting in a hybrid mechanism that includes a mobile platform for locomotion and a manipulator arm for manipulation. The structural complexity of a mobile manipulator is the main challenging issue because it includes several problems like adapting a manipulator and a redundancy mobile platform at non-holonomic constraints. The objective of the thesis is to fabricate an automated mobile manipulator and develop control algorithms that effectively coordinate the arm manipulation and mobility of mobile platform. The research work starts with deriving the motion equations of mobile manipulators. The derivation introduced here makes use of motion equations of robot manipulators and mobile platforms separately, and then integrated them as one entity. The kinematic analysis is performed in two ways namely forward & inverse kinematics. The motion analysis is performed for various WMPs such as, Omnidirectional WMP, Differential three WMP, Three wheeled omni-steer WMP, Tricycle WMP and Two steer WMP. From the obtained motion analysis results, Differential three WMP is chosen as the mobile platform for the developed mobile manipulator. Later motion analysis is carried out for 4-axis articulated arm. Danvit-Hartenberg representation is implemented to perform forward kinematic analysis. Because of this representation, one can easily understand the kinematic equation for a robotic arm. From the obtained arm equation, Inverse kinematic model for the 4-axis robotic manipulator is developed. Motion planning of an intelligent mobile robot is one of the most vital issues in the field of robotics, which includes the generation of optimal collision free trajectories within its work space and finally reaches its target position. For solving this problem, two evolutionary algorithms namely Particle Swarm Optimization (PSO) and Artificial Immune System (AIS) are introduced to move the mobile platform in intelligent manner. The developed algorithms are effective in avoiding obstacles, trap situations and generating optimal paths within its unknown environments. Once the robot reaches its goal (within the work space of the manipulator), the manipulator will generate its trajectories according to task assigned by the user. Simulation analyses are performed using MATLAB-2010 in order to validate the feasibility of the developed methodologies in various unknown environments. Additionally, experiments are carried out on an automated mobile manipulator. ATmega16 Microcontrollers are used to enable the entire robot system movement in desired trajectories by means of robot interface application program. The control program is developed in robot software (Keil) to control the mobile manipulator servomotors via a serial connection through a personal computer. To support the proposed control algorithms both simulation and experimental results are presented. Moreover, validation of the developed methodologies has been made with the ER-400 mobile platform

Locomotion system for ground mobile robots in uneven and unstructured environments

One of the technology domains with the greatest growth rates nowadays is service robots. The extensive use of ground mobile robots in environments that are unstructured or structured for humans is a promising challenge for the coming years, even though Automated Guided Vehicles (AGV) moving on flat and compact grounds are already commercially available and widely utilized to move components and products inside indoor industrial buildings. Agriculture, planetary exploration, military operations, demining, intervention in case of terrorist attacks, surveillance, and reconnaissance in hazardous conditions are important application domains. Due to the fact that it integrates the disciplines of locomotion, vision, cognition, and navigation, the design of a ground mobile robot is extremely interdisciplinary. In terms of mechanics, ground mobile robots, with the exception of those designed for particular surroundings and surfaces (such as slithering or sticky robots), can move on wheels (W), legs (L), tracks (T), or hybrids of these concepts (LW, LT, WT, LWT). In terms of maximum speed, obstacle crossing ability, step/stair climbing ability, slope climbing ability, walking capability on soft terrain, walking capability on uneven terrain, energy efficiency, mechanical complexity, control complexity, and technology readiness, a systematic comparison of these locomotion systems is provided in [1]. Based on the above-mentioned classification, in this thesis, we first introduce a small-scale hybrid locomotion robot for surveillance and inspection, WheTLHLoc, with two tracks, two revolving legs, two active wheels, and two passive omni wheels. The robot can move in several different ways, including using wheels on the flat, compact ground,[1] tracks on soft, yielding terrain, and a combination of tracks, legs, and wheels to navigate obstacles. In particular, static stability and non-slipping characteristics are considered while analyzing the process of climbing steps and stairs. The experimental test on the first prototype has proven the planned climbing maneuver’s efficacy and the WheTLHLoc robot's operational flexibility. Later we present another development of WheTLHLoc and introduce WheTLHLoc 2.0 with newly designed legs, enabling the robot to deal with bigger obstacles. Subsequently, a single-track bio-inspired ground mobile robot's conceptual and embodiment designs are presented. This robot is called SnakeTrack. It is designed for surveillance and inspection activities in unstructured environments with constrained areas. The vertebral column has two end modules and a variable number of vertebrae linked by compliant joints, and the surrounding track is its essential component. Four motors drive the robot: two control the track motion and two regulate the lateral flexion of the vertebral column for steering. The compliant joints enable limited passive torsion and retroflection of the vertebral column, which the robot can use to adapt to uneven terrain and increase traction. Eventually, the new version of SnakeTrack, called 'Porcospino', is introduced with the aim of allowing the robot to move in a wider variety of terrains. The novelty of this thesis lies in the development and presentation of three novel designs of small-scale mobile robots for surveillance and inspection in unstructured environments, and they employ hybrid locomotion systems that allow them to traverse a variety of terrains, including soft, yielding terrain and high obstacles. This thesis contributes to the field of mobile robotics by introducing new design concepts for hybrid locomotion systems that enable robots to navigate challenging environments. The robots presented in this thesis employ modular designs that allow their lengths to be adapted to suit specific tasks, and they are capable of restoring their correct position after falling over, making them highly adaptable and versatile. Furthermore, this thesis presents a detailed analysis of the robots' capabilities, including their step-climbing and motion planning abilities. In this thesis we also discuss possible refinements for the robots' designs to improve their performance and reliability. Overall, this thesis's contributions lie in the design and development of innovative mobile robots that address the challenges of surveillance and inspection in unstructured environments, and the analysis and evaluation of these robots' capabilities. The research presented in this thesis provides a foundation for further work in this field, and it may be of interest to researchers and practitioners in the areas of robotics, automation, and inspection. As a general note, the first robot, WheTLHLoc, is a hybrid locomotion robot capable of combining tracked locomotion on soft terrains, wheeled locomotion on flat and compact grounds, and high obstacle crossing capability. The second robot, SnakeTrack, is a small-size mono-track robot with a modular structure composed of a vertebral column and a single peripherical track revolving around it. The third robot, Porcospino, is an evolution of SnakeTrack and includes flexible spines on the track modules for improved traction on uneven but firm terrains, and refinements of the shape of the track guidance system. This thesis provides detailed descriptions of the design and prototyping of these robots and presents analytical and experimental results to verify their capabilities

In Depth Analysis of Power Balance, Handling, and the Traction Subsystem of an Articulated Skid-Steering Robot for Sustainable Agricultural Monitoring

This paper reports on the energy balance test performed on Agri.Q, an eight-wheel articulated robot intended to be a sustainable monitoring tool within the precision agriculture paradigm, and proposes an in-depth analysis of the traction subsystem in order to develop an appropriate traction allocation strategy to improve navigation through hilly or mountainous crops. Tests were conducted on the contribution of the orientable photovoltaic panel to the mission duration and overall sustainability, showing that a suitable mission plan, including dedicated charging phases, could significantly increase the robot’s operating time. A series of simulations of circular trajectories of different curvature and at different longitudinal velocities on flat ground were performed, with the aim of mapping the robot’s behaviour at steady state. The results of the simulations were analysed, paying particular attention to the required torques, manoeuvrability and forces exchanged on the ground. The simulations conducted demonstrated and extended previous results obtained on similar robotic architectures, which suffer from significant understeer behaviour due to significant lateral wheel slip during turning. They also showed the limitations of currently employed traction motors, but also the advantages of a proper traction allocation strategy involving the rear module. Article highlights. Agri.Q energy balance tests have been carried out to assess its endurance and sustainability The traction and handling behaviours of Agri.Q were mapped and discussed in detail in order to improve them Agri.Q has proven to be a basis for the future implementation of precision agriculture to advance the SDG

Climbing and Walking Robots

With the advancement of technology, new exciting approaches enable us to render mobile robotic systems more versatile, robust and cost-efficient. Some researchers combine climbing and walking techniques with a modular approach, a reconfigurable approach, or a swarm approach to realize novel prototypes as flexible mobile robotic platforms featuring all necessary locomotion capabilities. The purpose of this book is to provide an overview of the latest wide-range achievements in climbing and walking robotic technology to researchers, scientists, and engineers throughout the world. Different aspects including control simulation, locomotion realization, methodology, and system integration are presented from the scientific and from the technical point of view. This book consists of two main parts, one dealing with walking robots, the second with climbing robots. The content is also grouped by theoretical research and applicative realization. Every chapter offers a considerable amount of interesting and useful information

Engineering Dynamics and Life Sciences

From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”

Vehicle and Traffic Safety

The book is devoted to contemporary issues regarding the safety of motor vehicles and road traffic. It presents the achievements of scientists, specialists, and industry representatives in the following selected areas of road transport safety and automotive engineering: active and passive vehicle safety, vehicle dynamics and stability, testing of vehicles (and their assemblies), including electric cars as well as autonomous vehicles. Selected issues from the area of accident analysis and reconstruction are discussed. The impact on road safety of aspects such as traffic control systems, road infrastructure, and human factors is also considered

Design of a Mobile Robotic Platform with Variable Footprint

This thesis presents an in-depth investigation to determine the most suitable mobile base design for a powerful and dynamic robotic manipulator. It details the design process of such a mobile platform for use in an indoor human environment that is to carry a two-arm upper-body humanoid manipulator system. Through systematic dynamics analysis, it was determined that a variable footprint holonomic wheeled mobile platform is the design of choice for such an application. Determining functional requirements and evaluating design options is performed for the platform’s general configuration, geometry, locomotion system, suspension, and propulsion, with a particularly in-depth evaluation of the problem of overcoming small steps. Other aspects such as processing, sensing and the power system are dealt with sufficiently to ensure the feasibility of the overall proposed design. The control of the platform is limited to that necessary to determine the appropriate mechanical components. Simulations are performed to investigate design problems and verify performance. A basic CAD model of the system is included for better design visualization. The research carried out in this thesis was performed in cooperation with the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt)’s Robotics and Mechatronics Institute (DLR RM). The DLR RM is currently utilizing the findings of this research to finish the development of the platform with a target completion date of May 2008