Spherical Mobile Robot Research Articles

Special spherical mobile robot for planetary surface exploration: A review

Considering the requirements of high scientific return, low cost, less complexity, and more reliability for the robot proposed by the extreme environment exploration task on the planet surface, this article comprehensively reviews the history of the special spherical robot used for extraterrestrial surface exploration and summarizes the environmental characteristics and task difficulties of different planet surface. This article compares the advantages of different types of ground spherical robots and points out the superiority of special spherical robots, such as omni-direction, airtightness, zero-radius turning, under-actuated, swarming, and lightweight. In addition, the research progress of special spherical robots for extraterrestrial exploration, such as wind ball, jumping ball, fly ball, ball with leg, pendulum driven ball, tensegrity structure, are reviewed respectively. Finally, the performance characteristics of all these robots are analyzed, their application scope given.

Development and Control of a Weight-Shifting Mechanism to Change the Nature of Sway of a Spherical Mobile Robot

Development and Control of a Weight-Shifting Mechanism to Change the Nature of Sway of a Spherical Mobile Robot

Error driven Fuzzy Logic Controller (FLC) for Spherical Mobile Robot: Simulation & Experimental Performance Analysis

Spherical mobile robot is a ball-shaped mobile robot that capable to move from one place to another to perform the desired tasks. The challenge for spherical mobile robot falls within control algorithm aspects, where it is nonlinear and highly under-actuated increases the difficulties to control its motion. In this paper, the potentiality of intelligent controller is explored to control the motion spherical mobile robot. An error driven Fuzzy Logic controller (FLC) which consist of modular of two Proportional-Derivative (PD) type FLC and a Proportional-Integral (PI) type FLC were designed and tested to control the position of the spherical mobile robot, angle of the rotation of the pendulum and the angular velocity of the spherical mobile robot, respectively. The performance of the controller was then optimized by tuning the input and output gain of the controller with Particle Swarm optimization (PSO) method. The performance of the robot without the controller and with optimized controller were compared and analysed. As a result, the performance of the system in the form of rise time and settling time of the robot to control its position managed to be reduced by 86% and 89% respectively with optimized PD-type. For PD-type FLC to control the rotation of the pendulum, it was capable to eliminate the overshoot and reduce it settling time by 35.5%. While the optimized PI-type FLC has managed to eliminate the steady state error and achieved it desired velocity setpoint in 1.2s. Lastly, all the designed controllers were successfully tested on the prototype of the spherical mobile robot to study the performance of the spherical mobile robot. However, the overall performance of the implemented designed controller has shown a minimum effectiveness. The controller managed to achieve the setpoint value but with low stability which result from the less accuracy of the hardware sensors.

Mechanism and Control of Spherical Mobile Robot Using an Omnidirectional Three-Wheel Internal Drive Unit

Mechanism and Control of Spherical Mobile Robot Using an Omnidirectional Three-Wheel Internal Drive Unit

과소 작동 문제를 갖는 구형 이동 로봇의 동적 표면 기법 기반의 비선형 제어

본 논문은 과소 작동 문제를 갖는 구형 이동 로봇의 동적 표면 제어를 제안한다. 구형 이동 로봇의 과소 작동 문제는 제어 성능을 저조하게 하거나 하드웨어의 내구성을 손상시킬 수 있다. 이를 해결하기 위해 구형 이동 로봇 시스템의 안정화를 위한 기준각도로 가상 각도를 도입하고 동적 표면 제어 기법을 이용하여 비선형 제어기를 설계한다. 안정성 확보를 위해서 Lyapunov 안정성 이론에 의해 모든 오차는 궁극적으로 균일하게 유계가 된다. 마지막으로 모의실험을 통해 제안한 제어 시스템의 성능을 검증한다.

Kinematic Modelling and Structural Analysis of a Spherical Robot: BALL-E

This paper presents a spherical mobile robot which is capable of executing rolling and walking motions. The proposed robot can also transform into a quadruped based on the terrain conditions. The advantage of combining these motions in the robot is that it improves the collision recovery and manoeuvrability over multiple terrains. Various conceptual designs are developed, and concept scoring is carried out to find the best design. The kinematic analysis is presented for the chosen design using the Denavit-Hartenberg (D-H) method. The inverse kinematics is solved using MATLAB and the corresponding robot configurations are plotted. The structural analysis of the robot is also completed using ANSYS Workbench.

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.

Research on novel spatial structure of power generation of spherical robot

Continuous energy supply is essential to spherical mobile robot in the Antarctic investigation. This paper puts forward energy harvesters that can generate electricity from the wind to achieve the long time and the long range exploration. The major contribution is to present the preliminary models of the energy harvester which uses the law of electromagnetic induction, and meanwhile the spatial structures about generating electricity are analyzed, and the influence of different structures on the power generation and efficiency will be obtained. In order to get the characteristics of power generation efficiency, this paper designs one element pipeline model and two element pipeline model, and then the motion of magnet in harvester will be simulated in different installed structures and wind speed. The varying rules of induced voltage are concluded at last. Finally, experiments are implemented based on the simulated model. The experimental results verify the dependability of different structural schemes of the robot and the validity of induced voltages’ varying rules. The results show that the induced electromotive force value obtained by the one element pipeline structure model is larger than the two element pipeline model, but the stability of the latter is better. Through the research in this paper, it can provide a basis for selecting a suitable spherical robot space structure according to the environmental conditions to improve the endurance.

Heavy-duty Spherical Mobile Robot Driven by Five Omni Wheels

Heavy-duty Spherical Mobile Robot Driven by Five Omni Wheels

A Novel Step Optimal Path Planning Algorithm for the Spherical Mobile Robot Based on Fuzzy Control

In order to improve the ability of the spherical mobile robot to navigate and move autonomously in an unknown environment. This paper proposed a novel step optimal path planning method based on fuzzy control. Firstly, by analyzing the motion model of the spherical mobile robot, the arrangement and debugging of the ultrasonic sensors (HC-SR04) were completed. Then, through multi-sensor fusion technology and D-H parameter method, a fuzzy controller for the spherical mobile robot was designed. Finally, the proposed fuzzy control method was applied to the path planning of spherical mobile robot in unknown environment, and tested by a series of simulations and experiments. The results showed that the step optimal method based on fuzzy control could ensure that the spherical mobile robot completed the path planning. The experimental results also verified the effectiveness and practicability of the proposed novel path planning method.

Spherical Mobile Robot Driven by Single Omni Wheel

This paper presents a new spherical mobile robot driven by single omni wheel. The physical model is that an arc track is built inside the sphere shell and can rotate around a spherical diameter freely. It supports one driving omni wheel and keeps the driving omni wheel touching the inside of the sphere shell. The touching friction force can drive the sphere rolling forward or backward. Steering drive can move the omni wheel running along the arc track, that leads the spherical mobile robot turning left or right. The omni wheel can run sphere shell in straight way and turn its direction freely at same time. The mechanism of the spherical mobile robot is described in detail, and its motion and dynamics coordinate systems are built to analysis. The preliminary analysis shows that the robot has a variety of good motion capabilities, such as obstacle crossing, jumping, small radius steering etc.

Design, Modeling, and Motion Analysis of a Novel Fluid Actuated Spherical Rolling Robot

This paper studies a novel fluid actuated system for a spherical mobile robot. The robot’s mechanism consists of two essential parts: circular pipes to lead spherical moving masses (cores) and an internal driving unit to propel the cores. The spherical shell of the robot is rolled by displacing the cores in the pipes filled with fluid. First, we describe the structure of the robot and derive its nonlinear dynamics using the D’Alembert principle. Next, we model the internal driving unit that actuates the core inside the pipe. The simulated driving unit is studied with respect to three important parameters—the input motor torque, the actuator size, and the fluid properties. The overall model of the robot is then used for analyzing motion patterns in the forward direction. Analytical studies show that the modeled robot can be implemented under the given design specifications.

Spherical Mobile Robot Designed with Single Omnidirectional Wheel Method

Spherical Mobile Robot Designed with Single Omnidirectional Wheel Method

Research Progress and Development Trend of Spherical Mobile Robots

Research Progress and Development Trend of Spherical Mobile Robots

Kinematics-based four-state trajectory tracking control of a spherical mobile robot driven by a 2-DOF pendulum

Spherical mobile robot has compact structure, remarkable stability, and flexible motion, which make it have many advantages over traditional mobile robots when applied in those unmanned environments, such as outer planets. However, spherical mobile robot is a special highly under-actuated nonholonomic system, which cannot be transformed to the classic chained form. At present, there has not been a kinematics-based trajectory tracking controller which could track both the position states and the attitude states of a spherical mobile robot. In this paper, the four-state (two position states and two attitude states) trajectory tracking control of a type of spherical mobile robot driven by a 2-DOF pendulum was studied. A controller based on the shunting model of neurodynamics and the kinematic model was deduced, and its stability was demonstrated with Lyapunov’s direct method. The control priorities of the four states were allocated according to the magnification of each state tracking error in order to firstly ensure the correct tracking of the position states. The outputs (motor speeds) of the controller were regulated according to the maximum speeds and the maximum accelerations of the actuation motors in order to solve the speed jump problem caused by initial state errors, and continuous and bounded outputs were obtained. The effectiveness including the anti-interference ability of the proposed trajectory tracking controller was verified through MATLAB simulations.

Spherical Mobile Robot Driven by Biorthogonal Omnidirectional Wheels

Spherical Mobile Robot Driven by Biorthogonal Omnidirectional Wheels

Point stabilization of nonholonomic spherical mobile robot using nonlinear model predictive control

Control of nonholonomic spherical mobile robot is a generalization of the classical ball-plate problem which is still challenging in robotic researches. In this paper, point stabilization of a nonholonomic spherical mobile robot actuated by two internal rotors is investigated. Since every kinematic trajectory is not always dynamically realizable for the spherical robot driven by two actuators, the mathematical model of the robot is derived based on the angular momentum conservation principle. The controllability of the robot is evaluated based on the obtained model and the uncontrollable configurations as well as their geometrical meaning are specified. To simultaneous control of position and orientation of the robot, a nonlinear model predictive control (NMPC) is developed for the first time and the stability analysis is performed through using Lyapunov stability theorem. The performance of the designed control system is assessed through computer simulations in different test conditions. The simulation results show the significant performance of the proposed NMPC in stabilization of the spherical shell from every initial configuration to every desired position and orientation even in the uncontrollable region. Considering additive bounded noises, the robust stabilization of the nonholonomic spherical robot by the NMPC is also assessed in simulations. A spherical mobile robot driven by two perpendicular rotors is investigated.The equations of motion are derived using angular momentum conservation principle.The controllability of the model is analyzed and its uncontrollable configurations are specified.A NMPC is designed to control the position and orientation of the spherical shell simultaneously.The stability of designed controller is proven and its performance is evaluated.

Controlling spherical mobile robot in a two-parametric friction model

The theoretical mechanical model of the spherical robot with the flywheels located in a sphere is considered. The described design is intended for the motion control of a sphere on various trajectories. In the paper, control algorithms of a sphere on basic trajectories are investigated; the movements from rotation on the point and the movements on a straight line piece before the basic movements on curvilinear trajectories are considered. The paper describes dynamical models of a sphere robot, different models of friction, as well as a two-parametrical model as the main model of friction. Technical possibility of realization of a sphere robot with flywheels is proved.

Control of an omnidirectional spherical mobile robot using an adaptive Mamdani-type fuzzy control strategy

In this study, a supervisory control system with an adaptive Mamdani-type fuzzy controller (AMFC) is used to control an omnidirectional spherical mobile robot (ODSMR). The system combines an adaptive Mamdani-type fuzzy controller and a supervisory controller for ODSMRs with unknown external disturbances. Tracking is provided by a Mamdani-type fuzzy controller that approximates a theoretically exact control law, and a separate controller is used to cancel the residual of the approximation error. The control law is derived using Lyapunov stability theory to ensure the stability of the closed-loop system. Many external factors can cause the system to become unstable, so a supervisory controller is included. A decoupled control approach provides a simple method to achieve asymptotic stability for a fourth-order nonlinear system. The main concept of this approach is to decouple the system into two subsystems. Then, the primary subsystem combines the information provided by the secondary subsystem to generate a control that drives both subsystems to their desired states. This platform can move in any direction with no constraints. The efficiency of the proposed controller is verified with tests on an actual robot. The contributions of this study are: (1) the implementation of an ODSMR and (2) the application of the proposed AMFC with a supervisory control system to real-time control of the ODSMR.

Dynamic analysis of a spherical mobile robot based on a tensegrity structure with two curved compressed members

The use of mechanically compliant tensegrity structures in mobile robotics is an attractive research topic. The mechanical properties and therefore the locomotion performance of mobile robots based on these structures can be adjusted reversibly during locomotion. In the present work, a rolling mobile robot, based on a simple tensegrity structure, consisting of two rigid disconnected curved members connected to a continuous net of eight prestressed tensioned members with pronounced elasticity, is considered. Pure rolling uniaxial locomotion and also planar locomotion can be realized with small control effort, induced by the movement of two internal masses. After kinematic considerations, the nonlinear equations of motion are derived and transient dynamic analyses are performed, to study the system behavior. Also the dependency of the rolling movement behavior on structural and actuation parameters is discussed. The uniaxial and planar locomotion performance of the system are verified experimentally.