Wheeled Mobile Robot Research Articles

Fisheye-based visual aligned regulation for wheeled mobile robots

In this paper, a fisheye-based visual servo regulation method is proposed for wheeled mobile robots, which utilizes motion planning algorithms to provide trajectories for driving the robot to desired poses in an aligned pattern. To satisfy the wide field-of-view (FOV) requirement in robotic systems, the image projection model of fisheye is analyzed, and derivation and estimation of homography for fisheye vision are implemented to facilitate robotic pose calculation. Compared with traditional visual regulation schemes, motion planning and trajectory tracking techniques are combined to make mobile robots reach given poses in the frontal aligned style, which guarantees the robot to move smoothly and is extendable such as for car-like robots. Desired image trajectories are calculated reversely by the fisheye model with respect to the planned geometric path, and then a tracking controller is employed for maneuvering the mobile robot. Simulation and comparative experimental results are collected to verify effectiveness of the proposed strategy.

PSO-based optimized neural network PID control approach for a four wheeled omnidirectional mobile robot

AbstractThe demand for automation using mobile robots has been increased dramatically in the last decade. Nowadays, mobile robots are used for various applications that are not attainable to humans. Omnidirectional mobile robots are one particular type of these mobile robots, which has been the center of attention for their maneuverability and ability to track complex trajectories with ease, unlike their differential type counterparts. However, one of the disadvantages of these robots is their complex dynamical model, which poses several challenges to their control approach. In this work, the modeling of a four-wheeled omnidirectional mobile robot is developed. Moreover, an intelligent Proportional Integral Derivative (PID) neural network control methodology is developed for trajectory tracking tasks, and Particle Swarm Optimization (PSO) algorithm is utilized to find optimized controller's weights. The simulation study is conducted using Simulink and Matlab package, and the results confirmed the accuracy of the proposed intelligent control method to perform trajectory tracking tasks.

Minimum-Time Trajectory Generation for Wheeled Mobile Systems Using Bézier Curves with Constraints on Velocity, Acceleration and Jerk.

This paper considers the problem of minimum-time smooth trajectory planning for wheeled mobile robots. The smooth path is defined by several Bézier curves and the calculated velocity profiles on individual segments are minimum-time with continuous velocity and acceleration in the joints. We describe a novel solution for the construction of a 5th order Bézier curve that enables a simple and intuitive parameterization. The proposed trajectory optimization considers environment space constraints and constraints on the velocity, acceleration, and jerk. The operation of the trajectory planning algorithm has been demonstrated in two simulations: on a racetrack and in a warehouse environment. Therefore, we have shown that the proposed path construction and trajectory generation algorithm can be applied to a constrained environment and can also be used in real-world driving scenarios.

Trajectory tracking control of super-twisting sliding mode of mobile robot based on neural network

Aiming at improving the response speed and robustness of wheeled mobile robots, this paper uses neural networks to identify the dynamic functions of mobile robots, and proposes an improved adaptive super-twisting sliding mode controller. First, this paper improves the sliding mode surface of super-twisting sliding mode control, which effectively speeds up the response speed of the system. Second, the robust adaptive law is utilized to eliminate the influence of uncertain parameters in super-twisting sliding mode control, which improves the robustness of the system and greatness reduces the chattering. In addition, the use of a high-gain observer to estimate the speed information of the mobile robot in real time avoids the shortcomings of direct measurement of speed information and realizes the output feedback control of the system.

Energy Consumption Analysis of the Selected Navigation Algorithms for Wheeled Mobile Robots

The article presents the research on navigation algorithms of a wheeled mobile robot with the use of a vision mapping system and the analysis of energy consumption of selected navigation algorithms, such as RRT and A-star. Obstacle maps were made with the use of an RGBW camera, and binary occupation maps were also made, which were used to determine the traffic path. To recreate the routes in hardware, a programmed Pure Pursuit controller was used. The results of navigation were compared on the basis of the forward kinematics model and odometry measurements. Quantities such as current, except (x, y, phi), and linear and angular velocities were measured in real time. As a result of the conducted research, it was found that the RRT star algorithm consumes the least energy to reach the designated target in the designated environment.

Koopman-Operator-Based Robust Data-Driven Control for Wheeled Mobile Robots

The Koopman operator theory offers a way to construct explicit control-oriented high-dimensional linear dynamical models for the original nonlinear systems, solely using the input–output data of the dynamical system. The modeling accuracy of the Koopman model largely depends on the basis functions (lifting functions), dimensionality, and data quality. However, there has not been a systematic way to solve the problems mentioned above. In this article, a Koopman-operator-based robust data-driven control framework is proposed for wheeled mobile robots, via incorporating tools from control theory, to solve the problem of modeling errors of the Koopman model. By employing an extended state observer, the modeling errors of the Koopman model, including unknown external disturbances, are online estimated and compensated in the control signal in real time. Then, sliding-mode control is used to synthesize the controller. Importantly, the method of virtual control input is proposed, to cope with the model errors arising from the rotational motion of all the mobile robots. Besides, stability analysis is conducted, and the optimal dimensionality of the Koopman model is experimentally selected. Finally, experimental tests on an omnidirectional mobile robot are carried out to verify the effectiveness of the proposed control scheme, in terms of tracking performance and robustness.

Joint actuator fault estimation and localization under Round-Robin protocol for wheeled mobile robot

In this paper, the joint actuator fault estimation (AFE) and the wheeled mobile robot (WMR) localization under the Round-Robin protocol (RRP) problems are concerned. In order to complete the joint AFE and the WMR localization, a nominal joint system is constructed, which consists of the drive subsystem and WMR localization subsystem. In the drive subsystem of the WMR, the DC motor is used as an actuator to drive the WMR. When the faults occur, the performance of the actuator will be degraded, and the mobility of the WMR will be affected. In order to maintain a satisfactory mobility of the WMR, the faults need to be estimated timely such that some appropriate decisions or remedies can be made. In the WMR localization subsystem, for saving the network resources, the RRP is introduced to schedule the transmission of sensor measurements used for the WMR localization. The purpose of this paper is, by designing a time-varying filter for the constructed joint nominal system, to ensure the filtering error to meet the given [Formula: see text] performance requirement, such that the joint AFE and the WMR localization can be achieved simultaneously. Specifically, the sufficient condition is derived first and then the desired filter gain is designed by the recursive linear matrix inequality technology. Finally, a simulation experiment is conducted to certify the usefulness of the proposed algorithm.

Investigation on the Mobile Wheeled Robot in Terms of Energy Consumption, Travelling Time and Path Matching Accuracy

The task of controlling a wheeled mobile robot is an important element of navigation algorithms. The control algorithm manages the robot’s movement in accordance with the path determined by the planner module, where the accuracy of mapping the given route is very important. Most often, mobile robots are battery-powered, which makes minimizing energy consumption and shortening travel time an important issue. For this reason, in this work, the mobile robot control algorithm was tested in terms of energy consumption, travel time and path mapping accuracy. During the research, a criterion was developed, thanks to which it was possible to select the optimal parameters of the pure pursuit algorithm that controls the movement of the tested robot. The research was carried out in the Laboratory of Intelligent Mobile Robots using the QBot2e mobile robot operating on the basis of differential drive kinematics. As a result of the research, optimal values of the control parameters were obtained, minimizing the travel time, energy consumption and mapping error of the given paths.

Nonlinear Adaptive Fuzzy Control Design for Wheeled Mobile Robots with Using the Skew Symmetrical Property

This research presents a nonlinear adaptive fuzzy control method as an analytical design and a simple control structure for the trajectory tracking problem in wheeled mobile robots with skew symmetrical property. For this trajectory tracking problem in wheeled mobile robots, it is not easy to find an analytical adaptive fuzzy control solution due to the complicated error dynamics between the controlled wheeled mobile robots and desired trajectories. For deriving the analytical adaptive fuzzy control law of this trajectory tracking problem, a filter link is firstly adopted to find the solvable error dynamics, then the research is based on the skew symmetrical property of the transformed error dynamics. This proposed nonlinear adaptive fuzzy control solution has the advantages of low computational resource consumption and elimination of modeling uncertainties. From the results for tracking two simulation scenarios (an S type trajectory and a square trajectory), the proposed nonlinear adaptive fuzzy control method demonstrates a satisfactory trajectory tracking performance for the trajectory tracking problem in wheeled mobile robots with huge modeling uncertainties and outperforms the existing H2 control method.

Formation control of nonholonomic wheeled mobile robots via fuzzy fractional-order integral sliding mode control

Formation control of nonholonomic wheeled mobile robots via fuzzy fractional-order integral sliding mode control

A Brownian–Markov stochastic model for cart-like wheeled mobile robots

Wheeled mobile robots are commonly used in a wide range of applications from automated warehouses to patrolling. A rigorous and accurate model describing their dynamics is then important for control and tracking. It is worth mentioning that the majority of these models in literature deal with deterministic settings. Therefore, they are not able to take into account stochastic uncertainty or non-predictable phenomena such as lateral grip loss. In this paper, we present a novel stochastic dynamic model which considers random perturbations, while also considering the effect of unknown dissipative external forces acting on wheeled mobile robots. In particular, our approach is based on a two-state hybrid system of Stochastic Differential Equations modeling the robot dynamics subject to Brownian motion noises, with transitions from one state to the other triggered by to a homogeneous Markov chain.

Reliable Monte Carlo localization for mobile robots

AbstractReliability is a key factor for realizing safety guarantee of fully autonomous robot systems. In this paper, we focus on reliability in mobile robot localization. Monte Carlo localization (MCL) is widely used for mobile robot localization. However, it is still difficult to guarantee its safety because there are no methods determining reliability for MCL estimate. This paper presents a novel localization framework that enables robust localization, reliability estimation, and quick relocalization, simultaneously. The presented method can be implemented using a similar estimation manner to that of MCL. The method can increase localization robustness to environment changes by estimating known and unknown obstacles while performing localization; however, localization failure of course occurs by unanticipated errors. The method also includes a reliability estimation function that enables a robot to know whether localization has failed. Additionally, the method can seamlessly integrate a global localization method via importance sampling. Consequently, quick relocalization from a failure state can be realized while mitigating noisy influence of global localization. We conduct three types of experiments using wheeled mobile robots equipped with a two‐dimensional LiDAR. Results show that reliable MCL that performs robust localization, self‐failure detection, and quick failure recovery can be realized.

Design and Analysis of Transformable Wheel-legged Mobile Robot

Wheeled mobile robot has good ground motion ability, fast moving speed and low energy consumption, but poor obstacle surmounting performance. In order to make the mobile robot have the motion performance in complex environments, the wheel mechanism and the wheel-leg mechanism are coupled and designed, and a deformable wheel-leg structure is designed. The mobile robot can not only move in the wheel mode, but also switch to the wheel-leg mode to adapt to the complex motion environment. The deformable wheel-leg mechanism is composed of a four-bar linkage, and the static analysis of key components is carried out in ANSYS.

I-Randomly Exploring Algorithm for Wheeled Mobile Robot Path Planning

An Improved-RRT-based route planning technique with navigable trajectories was proposed. In this research work, the classical RRT technique is enhanced by optimizing the Non-linear equations and extending the mechanism of the technique. At first, the proposed I-RRT Expansion procedure is done and a task called N-action is performed that could identify the navigable trajectory in the configuration space. Then, an efficient extend-based-obstacles avoidance action has been carried out in the chosen navigable trajectory that was traced by the proposed I-RRT Expansion procedure. Finally, a subsequent-operation process was performed to carry out the node trimming process and smoothening of the final optimal path traced by the I-RRT Expansion method. Trajectories that have been generated using the proposed Improved Rapidly-Exploring Random Tree (I- RRT) method not only satisfied direction constraints approach on both start and goal points, but also simultaneously guaranteed the effectiveness and continuity of the trajectory. Consequently, the trajectories produced by the non-linear vehicle systems like Wheeled Mobile Robots (WMRs) are found to be geometrically viable and dynamically feasible. The optimal trajectories for five identical scenarios each of grid size of 100 × 100 and each scenario consisting of different number of nodes (500, 750, 1000, 1250 and 1500) were generated and the proposed method Improved Rapidly-Exploring Random Tree (I-RRT) was applied to all the scenarios and the performances were evaluated. The simulation results illustrate that the time traversed by the wheeled mobile robot and the path lengths traced by the WMR to reach the goal using the proposed I-RRT algorithm in each scenario are reduced considerably when compared to the corresponding time traversed by the wheeled mobile robot and the path lengths traced by the WMR to reach the goal using the existing RRT algorithm.

Teleoperation of Wheeled Mobile Robot With Dynamic Longitudinal Slippage

The increasing demand for a wheeled mobile robot (WMR) in many special fields (e.g., planetary exploration) has generated new difficulties, one of which is caused by the wheel longitudinal slippage on soft terrains. Compared with the general teleoperation under wheel pure rolling (no slippage), the introduction of wheel slippage creates new issues that potentially cause WMR instability. A new bilateral teleoperator for WMR coupling with dynamic longitudinal slippage is presented in this article. The traditional dynamic model is augmented in the presence of wheel slippage, whereas the slippage-induced unstable elements are determined through passivity analysis. To compensate for the active energy at the slave site, this article proposes a conservative slippage-dependent local controller without online estimation for wheel slippage. The teleoperator is then designed by guaranteeing the passivity of the entire teleoperation system. Experiments validate that the proposed methods can result in a stable system on soft terrains with good performance.

Velocity and position tracking controllers for wheeled mobile robots

This paper studies the velocity and position tracking control problems of differential-drive wheeled mobile robots with nonholonomic constraints. We show that these control problems can be solved without using the robot's linear velocity in the feedback loop. The proposed control laws are based on the dynamic feedback linearization technique and render the origin of the closed-loop dynamics globally exponentially stable. The stability analysis is carried out using Lyapunov theory. Finally, to validate the developed theory we present experimental results on a differential-drive wheeled mobile robot.

Trajectory Tracking Control of the Wheeled Mobile Robot based on the Curve Tracking Algorithm

A controller based on the curve tracking algorithm is offered as a solution to the issue of the wheeled mobile robot’s trajectory not be precisely monitored. First, Utilizing a planar global coordinate system, the kinematics and dynamics models of the wheeled mobile robot is created. Then, the kinematic model of the actual and predicted trajectories is utilized to determine the trajectory tracking error of the wheeled mobile robot. By the trajectory tracking error system model, The curve tracking algorithm controller is employed in the outer loop control to remove the robot’s position and attitude deviation during trajectory tracking, while the PI controller is utilized in the inner loop control to precisely track the robot’s speed. The simulation results demonstrate that the suggested control technique can regulate the wheeled mobile robot’s pose error [xq yq θq]T within the ranges of 0.1m, 0.03m, and 0.03rad, which demonstrates the efficacy of the control approach.

Dizajni novog hibridnog kontrolera zasnovan na poboljšanoj verziji optimizacije sivi vuk za praćenje putanje mobilnog robota na točkovima

Nonholonomic wheeled mobile robots are considered to be multi-input multi-output systems that are performed in varying environments. This work presents the trajectory tracking control of a nonholonomic wheeled mobile robot (WMR). The Kinematic and the dynamic models of the robot were derived. A new hybrid controller was designed, which consisted of two controllers based on an optimization algorithm to solve the trajectory tracking problem. The first controller is the Fractional order PID controller, which is based on the kinematic model and has been applied to control the linear and the angular robot velocities, while the second controller is a linear quadratic regulator (LQR) and is based on the dynamic model used to control the motors' torques. A new, improved version of grey wolf optimization wasadopted to tune the parameters of the hybrid controller. The main goals of this improvement are rapid convergence towards a solution, reducing the effect of the wolves' random motion, and balancing exploitation and exploration processes. MATLAB software was used to simulate the results under an S-shape trajectory and to evaluate the robustness and performance of the proposed control unit. The simulation results demonstrated the adopted control system's activity and efficiency based on the mean square error (MSE) between the desired and actual trajectory. The values of MSE of trajectory in the X and Y directions and the orientation are [6.589*10-4(m) 8.421*10-5(m) 0.00401(rad)]T . Also, the adopted control system can generate smooth values of the control input signals without sharp spikes. The performance of the presented control system has been verified and compared with the results obtained from the other two control systems, and the simulation results have offered the superiority and effectiveness of the hybrid controller of this work.

Formation Control for Leader–Follower Wheeled Mobile Robots Based on Embedded Control Technique

The formation control problem for leader–follower wheeled mobile robots (WMRs) is investigated in this article. A formation control strategy is proposed based on the embedded control technique. Different from the conventional design philosophy of designing the formation controller based on the formation tracking errors directly, the proposed strategy decomposes the formation control task into two subtasks. One is the virtual signal generator (i.e., virtual follower) design, and the other is the trajectory tracking controller design. The virtual signal generator is devised to act as a virtual follower such that it “achieves” the desired formation control goal, whose output is taken as the reference trajectory for the follower. To solve the subtask of trajectory tracking controller design, an unconstrained controller and a constrained controller with saturated velocities are designed, respectively. A rigorous stability analysis of the closed-loop system is given under these two kinds of controllers. Comparative simulations and experiments among the unconstrained controller with higher gains/lower gains and the constrained controller are given to illustrate the feasibility and effectiveness of the proposed formation control strategy.

DESIGN OF A FUNCTIONAL MODEL OF A THREE-WHEELED MOBILE ROBOT

Mobile wheeled robots are one of the most widespread group of service robots today. The simplicity of their design and their ability to better negotiate difficult terrain places them at the forefront. In practice, it is possible to find a variety of mobilewheeled robots, which differ from each other in the number and arrangement of wheels, the variety of structural design, or the suspension of the wheels and their suspension. Current statistics confirm that mobile service robots on wheeled chassis are themost numerous design of all realized applications, technical practice has filled with the diversity of their design solutions. The diversity of wheeled mobile service robots is mainly in the design of the wheeled chassis, the solutions range from single-wheeled to multi-wheeled concepts, from simple variants of the chassis layout to special or combined systems. The purpose of the article is the design of a three-wheeled robot, which will include the derivation of a mathematical model, the construction of a simulation model and the creation of a model in CAD software. An important part of the robot analysis is a complete kinematic model of the mechanical system, which provides all the necessary kinematic quantities for both the dynamic model of the mechanical system (force application, link loading, sizing) and for control needs (synthesis of position and velocity controllers). It is mainly about the position and orientation of the end working point in time and the corresponding position of the individual links of the mechanism. The next step was the overall design of the electronic system by appropriately selecting the electronic components and also creating the overall electronic circuitry. Finally, an experimental realistic model of the mobile robot was created from the simulation results.