Velocity Of Mobile Robot Research Articles

Development of rapidly exploring random tree based autonomous mobile robot navigation and velocity predictions using K-nearest neighbors with fuzzy logic analysis

Development of rapidly exploring random tree based autonomous mobile robot navigation and velocity predictions using K-nearest neighbors with fuzzy logic analysis

Planning of Service Mobile Robot Based on Convolutional LSTM Network

This paper proposes method that can complete motion planning in one step using convolutional Long Short-Term Memory (LSTM) network. Service mobile robot movement from the starting position to the target position includes three main tasks: mapping, positioning, motion planning. The convolutional LSTM network mainly is used to complete motion planning. The input of the network is a GRB picture with obstacles, target position, starting position. The outputs of the network are linear velocity and angular velocity of service mobile robot. The convolution layer of the network is to mark obstacles, target position and starting position. LSTM layer describes the time characteristics of movement and full connected layer is used to smoothly fit linear velocity and angular velocity of service mobile robot. The convolutional LSTM network can complete tasks of path finding and control, that is, mapping pictures with obstacles, target position, starting position to linear velocity and angular velocity of service mobile robot. Compared with traditional separate solutions for motion tasks, this method has obvious advantages such as good fault tolerance and complete motion tasks planning in real time. In experiment, a mobile robot “Turtlebot” based on ROS systems was used to verify the effectiveness and convenience of the method for motion planning.

Force and Position–Velocity Coordination for Delayed Bilateral Teleoperation of a Mobile Robot

SummaryThis document proposes a control scheme for delayed bilateral teleoperation of a mobile robot, which it is sought to achieve a coordination of the master device position with the slave mobile robot velocity, and at the same time synchronize the force exerted by the operator with force applied by the environment over the mobile robot. This approach allows the operator to improve the sensitive perception of the remote environment in which the robot navigates while he generates commands to control the mobile robot motion. In this paper, variable and asymmetrical communication time delays are taken into account, as well as a non-passive model of the human operator, for which a novel model is proposed that has a more general structure than the typical ones used to date in the teleoperation field. Furthermore, based on the theoretical analysis presented, the state of convergence in the stationary response is obtained. In addition, an experimental performance evaluation is carried out, where the position–velocity error, force error and the time to complete the task are evaluated. In the tests, a human operator commands a remote mobile robot to push objects of different weight while he perceives the weight of each object through the force feedback system. As an outcome, the theoretical and practical results obtained allow concluding that a satisfactory trade-off between stability and transparency is reached.

Fault-tolerant control-based flexible AGV transportation in a seat assembly system

Abstract The cyclic nature of the production flow enables just-in-time planning and organization of the associated supply chains. In turn, disruptions in the operation of machinery and equipment, which occur in practice, lead to deviations from nominal operation times. That lead to changes in production takt time, making it necessary to adjust previously created schedules for delivery/reception of materials. Consequently since a control action should be taken to adjust transport operation times within a specified time range, the following problem of fault-tolerant cyclic scheduling boils down to the dual stage task composed of linear- and mixed-linear-integer programming. Its advantage is that it can compensate the effects of certain faults such as delays present in the assembly station or reduced velocities of mobile robots enabling the system to return to the previously scheduled delivery times.

Application of neural models as controllers in mobile robot velocity control loop

Abstract This paper presents the application of an inverse neural models used as controllers in comparison to classical PI controllers for velocity tracking control task used in two-wheel, differentially driven mobile robot. The PI controller synthesis is based on linear approximation of actuators with equivalent load. In order to obtain relevant datasets for training of feed-forward multi-layer perceptron based neural network used as neural model, the mathematical model of mobile robot, that combines its kinematic and dynamic properties such as chassis dimensions, center of gravity offset, friction and actuator parameters is used. Neural models are trained off-line to act as an inverse dynamics of DC motors with particular load using data collected in simulation experiment for motor input voltage step changes within bounded operating area. The performances of PI controllers versus inverse neural models in mobile robot internal velocity control loops are demonstrated and compared in simulation experiment of navigation control task for line segment motion in plane.

Robust 2D map building with motion-free ICP algorithm for mobile robot navigation

SUMMARYA new motion-free iterative closest point (ICP) algorithm is proposed for building a two-dimensional (2D) map for mobile robot navigation. A laser range finder (LRF) sensor is installed on a mobile robot to scan and measure the depth data of the environment to form a 2D map during mobile robot navigation. Because the scanning and navigation motions are performed independently, the scanned data contain distortions from the motions of the mobile robot. To compensate for the distortions, the proposed motion-free ICP algorithm estimates the effects of the dynamic motions of the robot on the scanning process. That is, the motion-free algorithm compensates for the distance measurement errors related to the dynamic changes in the mobile robot's velocity. Experiments were performed with actual velocity changes of a mobile robot to demonstrate and verify the effective performance of the proposed algorithm.

Robust finite-time tracking control of nonholonomic mobile robots without velocity measurements

The problem of robust finite-time trajectory tracking of nonholonomic mobile robots with unmeasurable velocities is studied. The contributions of the paper are that: first, in the case that the angular velocity of the mobile robot is unmeasurable, a composite controller including the observer-based partial state feedback control and the disturbance feed-forward compensation is designed, which guarantees that the tracking errors converge to zero in finite time. Second, if the linear velocity as well as the angular velocity of mobile robot is unmeasurable, with a stronger constraint, the finite-time trajectory tracking control of nonholonomic mobile robot is also addressed. Finally, the effectiveness of the proposed control laws is demonstrated by simulation.

Adaptive-observer-based dynamic surface tracking of a class of mobile robots with nonlinear dynamics considering unknown wheel slippage

This paper addresses an adaptive-observer-based control design problem for path tracking of a class of wheeled mobile robots in the presence of unknown slippage effects. The linear and angular velocities of mobile robots are assumed to be unmeasurable. This causes nonlinear coupling terms between the unmeasurable velocities and unknown skidding and slipping effects in the robot dynamics, making the design of an adaptive observer difficult. An adaptive observer is presented to estimate unmeasured velocities of the mobile robots and to compensate for the skidding and slipping effects. Then, a simple adaptive controller at the dynamic level is derived using dynamic surface design methodology. Fuzzy logic systems are employed to overcome the coupling problems between the unmeasurable velocities and unknown skidding and slipping effects in the controller design procedure. From Lyapunov stability analysis, the stability of the controlled closed-loop system is analyzed under slippage conditions.

Optimal placement of optical mice for accurate mobile robot velocity estimation

There can be some restrictions during the installation of optical mice at the bottom of a mobile robot, owing to the non-circular base or other existing structures of the robot. This paper presents the optimal placement of optical mice under positional restriction during installation for the velocity estimation of a mobile robot. First, the velocity kinematics between a mobile robot and an array of two or more optical mice is derived, mapping the velocity of a mobile robot in the world coordinate frame to the velocities of optical mice in their local frames. Second, the error characteristics of the velocity estimation of a mobile robot are represented by the uncertainty ellipsoid, and the performance index is then defined as the inverse of the volume of the ellipsoid, which should be minimized for the optimal placement of optical mice. Third, the global optimization strategy is stated in terms of the distances to each optical mouse and the geometrical center of all optical mice, and the local optimization strategy is described as the positional change of each optical mouse, leading to optimal optical mouse placement. Fourth, simulation results for three optical mice within a given elliptical region are given to show how the positional restriction during installation affects the resulting optimal optical mouse placement.

Isotropic Optical Mouse Placement for Mobile Robot Velocity Estimation

This paper presents the isotropic placement of multiple optical mice for the velocity estimation of a mobile robot. It is assumed that there can be positional restriction on the installation of optical mice at the bottom of a mobile robot. First, the velocity kinematics of a mobile robot with an array of optical mice is obtained and the resulting Jacobian matrix is analysed symbolically. Second, the isotropic, anisotropic and singular optical mouse placements are identified, along with the corresponding characteristic lengths. Third, the least squares mobile robot velocity estimation from the noisy optical mouse velocity measurements is discussed. Finally, simulation results for several different placements of three optical mice are given.

Tracking control of a nonholonomic mobile robot using compound cosine function neural networks

The purpose of this paper is to propose a compound cosine function neural network with continuous learning algorithm for the velocity and orientation angle tracking control of a nonholonomic mobile robot with nonlinear disturbances. Herein, two neural network (NN) controllers embedded in the closed-loop control system have the simple continuous learning and rapid convergence capability without the dynamics information of the mobile robot to realize the adaptive control of the mobile robot. The neuron function of the hidden layer in the three-layer feed-forward network structure is on the basis of combining a cosine function with a unipolar sigmoid function. The developed neural network controllers have simple algorithm and fast learning convergence because the weight values are only adjusted between the nodes in hidden layer and the output nodes, while the weight values between the input layer and the hidden layer are one, i.e. constant, without the weight adjustment. Therefore, the main advantages of this control system are the real-time control capability and the robustness by use of the proposed neural network controllers for a nonholonomic mobile robot with nonlinear disturbances. Through simulation experiments applied to the nonholonomic mobile robot with the nonlinear disturbances which are considered as dynamics uncertainty and external disturbances, the simulation results show that the proposed NN control system of nonholonomic mobile robots has real-time control capability, better robustness and higher control precision. The compound cosine function neural network provides us with a new way to solve tracking control problems for mobile robots.

Wheeled Mobile Robot Tracking Control without Velocity Measurement

In this paper, a new robust trajectory tracking control scheme for wheeled mobile robots without velocity measurement is proposed. In the proposed controller, the velocity observer is used to estimate the velocity of wheeled mobile robot. The dynamics of wheeled mobile robot is considered to develop the controller. The proposed controller has the following features: i) The proposed controller has good robustness performance; ii) It is easy to improve tracking performance by setting only one design parameters.

이동로봇 속도 추정 성능 향상을 위한 광 마우스의 최적 배열

This paper presents the optimal array of optical mice for the accurate velocity estimation of a mobile robot. It is assumed that there can be some restriction on the installation of two or more optical mice at the bottom of a mobile robot. First, the velocity kinematics of a mobile robot with an array of optical mice is derived, which maps the velocity of a mobile robot to the velocities of optical mice. Second, taking into account the consistency in physical units, the uncertainty ellipsoid is obtained to represent the error characteristics of the mobile robot velocity estimation owing to noisy optical mouse measurements. Third, a simple but effective performance index is defined as the inverse of the volume of the uncertainty ellipsoid, which can be used for the optimization of the optimal optical mouse placement. Fourth, simulation results for the optimal placement of three optical mice within a given elliptical region are given.

Systematic robustness analysis of least squares mobile robot velocity estimation using a regular polygonal optical mouse array

This paper presents the systematic robustness analysis for the least squares velocity estimation of a mobile robot using a polygonal array of optical mice. First, the least squares velocity estimation of a mobile robot is obtained as the simple average of the velocity readings from optical mice. Second, the robustness of the proposed mobile robot velocity estimation is analyzed in terms of measurement noises, partial malfunctions, and imprecise installation of optical mice. Some experimental results are given to demonstrate the validity and performance of the proposed method.

Adaptive Trajectory Tracking Control for a Nonholonomic Mobile Robot

As one of the core issues of the mobile robot motion control, trajectory tracking has received extensive attention. At present, the solution of the problem only takes kinematic or dynamic model into account separately, so that the presented strategy is difficult to realize satisfactory tracking quality in practical application. Considering the unknown parameters of two models, this paper presents an adaptive controller for solving the trajectory tracking problem of a mobile robot. Firstly, an adaptive kinematic controller utilized to generate the command of velocity is designed based on Backstepping method. Then, in order to make the real velocity of mobile robot reach the desired velocity asymptotically, a dynamic adaptive controller is proposed adopting reference model and Lyapunov stability theory. Finally, through simulating typical trajectories including circular trajectory, fold line and parabola trajectory in normal and perturbed cases, the results illustrate that the control scheme can solve the tracking problem effectively. The proposed control law, which can tune the kinematic and dynamic model parameters online and overcome external disturbances, provides a novel method for improving trajectory tracking performance of the mobile robot.

실내 자율형 주행로봇의 자기위치 추정을 위한 보상필터 설계

This paper present an effective complementary filtering method using encoder and gyro sensors for the self-localization(including heading and velocity) of indoor mobile robot. The main idea of the proposed approach is to find the pros and cons of each sensor through a various maneuvering tests and to design of an adaptive complementary filter that works for the entire maneuvering phases. The proposed method is applied to an indoor mobile robot and the performances are verified through extensive experiments.

실내 GPS 환경에서 로봇의 이동속도기반 강인한 위치 및 방향 추정

실내 복잡한 환경에서 이동 로봇의 정확한 이동 동작과 작업의 정확도를 높이기 위해서는 보다 정확한 위치 및 방향 추정이 요구된다. 본 논문에서는 실내 환경에서 이동 로봇이 실내 GPS(iGPS) 정보와 이동속도를 기반으로 위치 및 진행 방향을 강인하게 추정하는 기법을 제안하였다. 초음파를 사용한 iGPS를 기반으로 하는 실내 위치 추정 시스템은 외부 잡음과 초음파 자체의 오차를 가지고 있다. 외부 잡음과 자체 오차 한계를 가지는 환경에서 강인한 위치 및 방향 추정 시스템을 구현하기 위해 로봇의 이동 속도와 취득된 위치 정보의 불확실성을 고려한 소속 함수를 활용하여 강인한 추정 시스템을 제안하였다. 제안된 추정방법은 센서의 개수와 다양한 위치 오차를 고려한 모의실험을 통해 검증하였다. The accurate estimation of position and direction of the mobile robot is essential for preparing precise movement and works in the inner complex environment. In this paper, we propose a robust estimation method of location and direction using the velocity of mobile robot in the inner GPS environment. The estimation using the inner GPS with ultrasonic sensors have to consider with various acoustic noise and sensor errors. We design a robust estimation method using a membership function based on uncertainty of the obtained information and robot velocity. The simulation results of the proposed method show effectiveness in the contaminated environment with position errors.

加速度制限付き最速誘導制御実験

This paper discusses experimentally how to control velocity of mobile robot as fast as possible with a condition of not letting carrying objects slip on it, while guiding the mobile robot onto a desired traveling course designated arbitrarily as preconditions. The requirements of above control objectives seem to be standing against each other. We have confirmed that our approach to this knotted problem could control the traveling speed within a velocity extent of making the carrying objects kept stationary on the mobile robot. The proposed fastest guidance control method has been examined intensively through sinusoidal course traveling and rectangular course traveling experiments.

ROBUST MOBILE ROBOT VELOCITY ESTIMATION USING A POLYGONAL ARRAY OF OPTICAL MICE

This paper presents the robust velocity estimation of a mobile robot using a polygonal array of optical mice that are installed at the bottom of the mobile robot. First, the velocity kinematics from a mobile robot to an array of optical mice is derived, from which the least squares estimation of a mobile robot velocity is obtained. Second, the least squares mobile robot velocity estimation is shown to be robust against measurement noises and partial malfunctions of optical mice. Third, in the presence of installation error, a practical method for optical mouse position calibration is devised. Finally, some experimental results are given to demonstrate the validity and performance of the proposed mobile robot velocity estimation.

정다각형 배열의 광 마우스를 이용한 이동 로봇의 최소 자승 속도 추정

This paper presents the velocity estimation of a mobile robot using a regular polygonal array of optical mice that are installed at the bottom of a mobile robot. First, the basic principle of the proposed velocity estimation method is explained. Second, the velocity kinematics from a mobile robot to an array of optical mice is derived as an overdetermined linear system. Third, for a given set of optical mouse readings, the mobile robot velocity is estimated based on the least squares solution to the obtained system. Finally, simulation results are given to demonstrate the validity of the proposed velocity estimation method.