Dynamic Modelling and Velocity Control of a Two-Wheeled Inverted Pendulum Robot

With the advancement of Industry 4.0, mobile robots are being applied to more and more tasks, in areas such as exploring unfamiliar environments, inspecting and monitoring infrastruc- ture, finding and rescuing people, or transporting and handling loads, among others. In this project we will focus on the modeling and control of two-wheeled inverted pendulum robots. Although they must be actively stabilized to prevent them from tipping over, these systems have several advantages over stable robots with more wheels: they can rotate around a point without moving, compensate external force disturbances that would tip over a conventional robot, and achieve taller and slimmer geometries while being stable. Along the project we will see how the kinematic and dynamic models for a twinbot (two-wheeled inverted pendulum robot) are obtained, we will go over the design of a control system, that, using the dynamic model, stabilizes the robot in the upright position along a real time defined trajectory, and we will end up validating the robustness of this control by applying force disturbances while the robot is trying to follow a defined trajectory

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

Keep Rollin' - Whole-Body Motion Control and Planning for Wheeled Quadrupedal Robots

We show dynamic locomotion strategies for wheeled quadrupedal robots, which combine the advantages of both walking and driving. The developed optimization framework tightly integrates the additional degrees of freedom introduced by the wheels. Our approach relies on a zero-moment point based motion optimization which continuously updates reference trajectories. The reference motions are tracked by a hierarchical whole-body controller which computes optimal generalized accelerations and contact forces by solving a sequence of prioritized tasks including the nonholonomic rolling constraints. Our approach has been tested on ANYmal, a quadrupedal robot that is fully torque-controlled including the non-steerable wheels attached to its legs. We conducted experiments on flat and inclined terrains as well as over steps, whereby we show that integrating the wheels into the motion control and planning framework results in intuitive motion trajectories, which enable more robust and dynamic locomotion compared to other wheeled-legged robots. Moreover, with a speed of 4 m/s and a reduction of the cost of transport by 83 % we prove the superiority of wheeled-legged robots compared to their legged counterparts.Comment: IEEE Robotics and Automation Letter

A new approach to the kinematic modeling of a three-dimensional car-like robot with differential drive using computational mechanics

[EN] This article presents a kinematic analysis of a four-wheeled mobile robot in three-dimensions, introducing computational mechanics. The novelty lies in (1) the type of robot that is analyzed, which has been scarcely dealt with in the literature, and (2) the methodology used which enables the systematic implementation of kinematic algorithms using the computer. The mobile robot has four wheels, four rockers (like an All-Terrain Mobile Robot), and a main body. It also has two actuators and uses a drive mechanism known as differential drive (like those of a slip/skid mobile robot). We characterize the mobile robot as a set of kinematic closed chains with rotational pairs between links and a higher contact pair between the wheels and the terrain. Then, a set of generalized coordinates are chosen and the constraint equations are established. A new concept named ¿driving modes¿ has been introduced because some of the constraint equations are derived from these. The kinematics is the first step in solving the dynamics of this robot in order to set a control algorithm for an autonomous car-like robot. This methodology has been successfully applied to a real mobile robot, ¿Robotnik,¿ and the results are analyzed.Rubio Montoya, FJ.; Llopis Albert, C.; Valero Chuliá, FJ.; Besa Gonzálvez, AJ. (2019). A new approach to the kinematic modeling of a three-dimensional car-like robot with differential drive using computational mechanics. Advances in Mechanical Engineering. 11(3):1-14. https://doi.org/10.1177/1687814019825907S114113Campion, G., Bastin, G., & Dandrea-Novel, B. (1996). Structural properties and classification of kinematic and dynamic models of wheeled mobile robots. IEEE Transactions on Robotics and Automation, 12(1), 47-62. doi:10.1109/70.481750Bajracharya, M., Maimone, M. W., & Helmick, D. (2008). Autonomy for Mars Rovers: Past, Present, and Future. Computer, 41(12), 44-50. doi:10.1109/mc.2008.479Poczter, S. L., & Jankovic, L. M. (2013). The Google Car: Driving Toward A Better Future? Journal of Business Case Studies (JBCS), 10(1), 7. doi:10.19030/jbcs.v10i1.8324Wang, T., Wu, Y., Liang, J., Han, C., Chen, J., & Zhao, Q. (2015). Analysis and Experimental Kinematics of a Skid-Steering Wheeled Robot Based on a Laser Scanner Sensor. Sensors, 15(5), 9681-9702. doi:10.3390/s150509681Alexander, J. C., & Maddocks, J. H. (1989). On the Kinematics of Wheeled Mobile Robots. The International Journal of Robotics Research, 8(5), 15-27. doi:10.1177/027836498900800502Muir, P. F., & Neuman, C. P. (1987). Kinematic modeling of wheeled mobile robots. Journal of Robotic Systems, 4(2), 281-340. doi:10.1002/rob.4620040209Tarokh, M., & McDermott, G. J. (2005). Kinematics modeling and analyses of articulated rovers. IEEE Transactions on Robotics, 21(4), 539-553. doi:10.1109/tro.2005.847602Zhang, N., Zhao, Y., Wei, H., & Chen, G. (2016). Experimental study on the influence of air injection on unsteady cloud cavitating flow dynamics. Advances in Mechanical Engineering, 8(11), 168781401667667. doi:10.1177/168781401667667

The Problem of Adhesion Methods and Locomotion Mechanism Development for Wall-Climbing Robots

This review considers a problem in the development of mobile robot adhesion methods with vertical surfaces and the appropriate locomotion mechanism design. The evolution of adhesion methods for wall-climbing robots (based on friction, magnetic forces, air pressure, electrostatic adhesion, molecular forces, rheological properties of fluids and their combinations) and their locomotion principles (wheeled, tracked, walking, sliding framed and hybrid) is studied. Wall-climbing robots are classified according to the applications, adhesion methods and locomotion mechanisms. The advantages and disadvantages of various adhesion methods and locomotion mechanisms are analyzed in terms of mobility, noiselessness, autonomy and energy efficiency. Focus is placed on the physical and technical aspects of the adhesion methods and the possibility of combining adhesion and locomotion methods