Tip-over stability enhancement for omnidirectional mobile robot

2014 ◽  
Vol 2 (2) ◽  
pp. 91-106 ◽  
Author(s):  
Muhammad Juhairi Aziz Safar ◽  
Keigo Watanabe ◽  
Shoichi Maeyama ◽  
Isaku Nagai
Keyword(s):  
Mobile Robot ◽  
Content Type ◽  
Omnidirectional Mobile Robot ◽  
Control Moment ◽  
Enhancement Method ◽  
Angle Stability ◽  
The Stability ◽  
Stability Enhancement ◽  
Stable Trajectory ◽  
Control Moment Gyro

Purpose – The purpose of this paper is to analyze the stability behavior of the omnidirectional mobile robot with active dual-wheel caster (ADWC) assemblies and provide a stable trajectory without any tip-over incident. The omnidirectional mobile robot to be developed is for transporting cuboid-shaped objects. Design/methodology/approach – The omnidirectional transport mobile robot is designed using an ADWC assemblies structure, the tip-over occurrence is estimated based on the support forces of an active footprint, the tip-over direction is predicted, the tip-over stability is enhanced to prevent the tip-over occurrence and a fast traveling motion is provided. Findings – The omnidirectional mobile robot tends to tip-over more on the sides with small ranges of tip-over angle. The proposed method for estimating the tip-over occurrence and enhancing the stability using the gyroscopic torque device was feasible as the tip-over prevention system of the omnidirectional mobile robot with ADWC assemblies. Originality/value – The research addresses the study of the tip-over stability for the omnidirectional mobile robot that possesses an active footprint. It also addresses the prediction of the tip-over occurrence using the derived dynamical model together with force-angle stability measure and the tip-over stability enhancement method using a single-gimbal control moment gyro device.

Wave-transmitting method for a travelling-wave-type omnidirectional mobile robot

2015 ◽  
Vol 42 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Masashi Konno ◽  
Yutaka Mizota ◽  
Taro Nakamura
Keyword(s):  
Mobile Robot ◽  
Contact Area ◽  
Travelling Waves ◽  
Travelling Wave ◽  
Propagation Mechanism ◽  
Ground Contact ◽  
Wave Type ◽  
Content Type ◽  
Omnidirectional Mobile Robot ◽  
Magnetic Attraction

Purpose – This paper aims to develop a wave-transmitting mechanism for a travelling-wave-type omnidirectional mobile robot. Existing omnidirectional mechanisms are prone to movement instability because they establish a small contact area with the ground. The authors have developed a novel omnidirectional mobile robot that achieves stable movement by a large ground-contact area. The proposed robot moves by a wave-transmitting mechanism designed for this purpose. Design/methodology/approach – To achieve stable movement, a spiral-type travelling-wave-propagation mechanism that mimics the locomotion mechanism of a snail was developed. The mechanism was applied to an omnidirectional mobile robot. Findings – The practicality of magnetic attraction was verified in experiments of the wave-transmitting mechanism. Moreover, omnidirectional movement was confirmed in a robot prototype adopting this mechanism. Research limitations/implications – The proposed robot will eventually be deployed in human spaces such as factories and hospitals. A mechanically improved version of the robot will be evaluated in load-driving experiments and equipped with control systems. Originality/value – This paper proposes an omnidirectional mobile robot with a large ground contact area that moves by continuous travelling waves. The practicability of this mechanism was experimentally confirmed, and a prototype robot achieved omnidirectional movement.

Tip over Stability Analysis of a Three-Wheeled Mobile Robot Capable of Traversing Uneven Terrains without Slip

2011 ◽  
Vol 110-116 ◽  
pp. 2940-2947 ◽  
Author(s):  
Tharakeshwar Appala ◽  
Ashitava Ghosal
Keyword(s):  
Stability Analysis ◽  
Mobile Robot ◽  
Wheeled Mobile Robot ◽  
Free Motion ◽  
Lateral Tilt ◽  
Uneven Terrain ◽  
Stability Measure ◽  
Angle Stability ◽  
The Stability ◽  
Measure Technique

A mobile robot traversing an uneven terrain can undergo tip over instability when one or more wheels of the mobile robot losses contact with the uneven terrain. In this paper, we study the tip over stability of a three wheeled mobile robot. The three wheeled mobile robot studied in this paper has torus shaped rear wheels and have the ability of lateral tilting – a condition required for slip free motion on uneven terrain. The torus shaped wheels and slip free motion makes the dynamics and tip over stability analysis more difficult and interesting. In this paper, the force-angle stability measure technique is used to analyze and detect tip over instability. Simulation results of the stability analysis shows that the wheeled mobile robot with lateral tilt of rear wheels is capable of moving on certain kinds of rough terrains without tip over.

Autonomous omnidirectional mobile robot navigation based on hierarchical fuzzy systems

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Najla Krichen ◽  
Mohamed Slim Masmoudi ◽  
Nabil Derbel
Keyword(s):  
Mobile Robot ◽  
Obstacle Avoidance ◽  
Fuzzy Systems ◽  
Fuzzy Controller ◽  
Fuzzy Rules ◽  
Infrared Sensors ◽  
Content Type ◽  
Omnidirectional Mobile Robot ◽  
Simulation Results ◽  
Hierarchical Fuzzy Systems

Purpose This paper aims to propose a one-layer Mamdani hierarchical fuzzy system (HFS) to navigate autonomously an omnidirectional mobile robot to a target with a desired angle in unstructured environment. To avoid collision with unknown obstacles, Mamdani limpid hierarchical fuzzy systems (LHFS) are developed based on infrared sensors information and providing the appropriate linear speed controls. Design/methodology/approach The one-layer Mamdani HFS scheme consists of three fuzzy logic units corresponding to each degree of freedom of the holonomic mobile robot. This structure makes it possible to navigate with an optimized number of rules. Mamdani LHFS for obstacle avoidance consists of a number of fuzzy logic units of low dimension connected in a hierarchical structure. Hence, Mamdani LHFS has the advantage of optimizing the number of fuzzy rules compared to a standard fuzzy controller. Based on sensors information inputs of the Mamdani LHFS, appropriate linear speed controls are generated to avoid collision with static obstacles. Findings Simulation results are performed with MATLAB software in interaction with the environment test tool “Robotino Sim.” Experiments have been done on an omnidirectional mobile robot “Robotino.” Simulation results show that the proposed approaches lead to satisfied performances in navigation between static obstacles to reach the target with a desired angle and have the advantage that the total number of fuzzy rules is greatly reduced. Experimental results prove the efficiency and the validity of the proposed approaches for the navigation problem and obstacle avoidance collisions. Originality/value By comparing simulation results of the proposed Mamdani HFS to another navigational controller, it was found that it provides better results in terms of path length in the same environment. Moreover, it has the advantage that the number of fuzzy rules is greatly reduced compared to a standard Mamdani fuzzy controller. The use of Mamdani LHFS in obstacle avoidance greatly reduces the number of involved fuzzy rules and overcomes the complexity of high dimensionality of the infrared sensors data information.

High-Precision Control for Magnetically Suspended Rotor of a DGMSCMG Based on Motion Separation

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Jinjin Xie ◽  
Gang Liu ◽  
Hu Liu
Keyword(s):  
High Precision ◽  
Control Strategy ◽  
Sliding Mode ◽  
Switching Function ◽  
Torsional Motion ◽  
Precision Control ◽  
Rotating Speed ◽  
Control Moment ◽  
The Stability ◽  
Control Moment Gyro

The magnetically suspended rotor (MSR) in a double-gimbal magnetically suspended control moment gyro (DGMSCMG) is a complicated system with multivariable, nonlinearity, and strong coupling. Not only the torsional motion of the MSR is coupled depend on the rotating speed but also its translational and torsional motions at the same axis are coupled due to the asymmetric position stiffness of magnetic bearings. Besides, the MSR also encounters the nonlinear coupling torque due to gimbals' movements. These problems influence the control accuracy of the MSR. To resolve these issues, this work presents a high-precision control strategy. A compensation method for asymmetric position stiffness is proposed to realize separation between the translational and torsional motions. Then the integral sliding mode control based on motion separation (MSISMC) is employed to stabilize the translational and torsional dynamics. To suppress the coupling torque from gimbals' movements, a novel switching function considering the estimation of the coupling torque is designed in torsional controller, and the decoupling control for the torsional motion is implemented by pole assignments. The stability of the closed-loop MSR control system is analyzed by the Lyapunov and state space methods. Comparative simulations and experiments verify the effectiveness and superiority of the proposed control strategy.

Stability Measures and Criteria for Autonomous Mobile Robotic Platforms: Analysis, Comparison and Numerical Evaluation

2019 ◽  
Author(s):  
Kaveh Nazem Tahmasebi ◽  
Roberto Belotti ◽  
Renato Vidoni ◽  
Karl Von Ellenrieder
Keyword(s):  
Mobile Robot ◽  
Center Of Mass ◽  
Stability Margin ◽  
Base Surface ◽  
Point Energy ◽  
Stability Margins ◽  
Stability Measure ◽  
Mass Moment ◽  
Angle Stability ◽  
The Stability

Abstract The tip-over instability of an autonomous mobile robot is a significant problem as it can diminish its maneuverability and increase the possibility of damaging the robot and its surrounding environment. For these reasons, it is important to define the stability margin and predict the edge of the tip-over instability considering different robot specifications and environmental conditions. Different stability measures have been developed to evaluate and analyze robot stability margins for diverse conditions. In this work, the Zero Moment Point, Energy Stability Margin, Force-Angle Stability Measure, and Mass-Moment Height Stability Measure methods are considered and applied to different mobile robot architectures including three-wheeled, four-wheeled (with rectangular and trapezoidal base surface) and articulated systems. The stability margins are discussed considering the four different stability criteria and evaluating the effect of a sloped surface. Then, the sensitivity of the tip-over instability in relation to the variation of the center of mass height as an important robot configuration parameter is evaluated. Finally, after a theoretical extension of the Force-Angle Stability and Mass-Moment Height stability measurement methods, the articulated mobile robot’s stability margin is considered and evaluated.

Comparing fluid ring and CMG servomechanisms for active control of rigid satellites

2018 ◽  
Vol 90 (6) ◽  
pp. 896-905 ◽  
Author(s):  
Saleh Akbaritabar ◽  
Reza Esmaelzadeh ◽  
Reza Zardashti
Keyword(s):  
Attitude Control ◽  
Design Methodology ◽  
Torque Control ◽  
Performance Parameters ◽  
Attitude Control System ◽  
Content Type ◽  
Control Moment ◽  
Attitude Maneuver ◽  
Control Moment Gyro ◽  
Practical Implications

Purpose This paper aims to describe a novel type of attitude control system (ACS) in different configurations. This servomechanism is compared with control moment gyro (CMG) in significant parameters of performance for ACS of rigid satellite. Design/methodology/approach This new actuator is the fluid containing one or more rings and fluid flow is supplied by pump. The required torque control is obtained by managing fluid angular velocity. The cube-shaped satellite with three rings of fluid in the principle axes is considered for modeling. The satellite is considered rigid and nonlinear dynamics equation is used for it. In addition, the failure of the pyramid-shaped satellite with an additional ring fluid is discussed. Findings The controller model for four fluid rings has more complexity than for three fluid rings. The simulation results illustrated that four fluid rings need less energy for stabilization than three fluid rings. The performance of this type of actuator is compared with CMG. At last, it is demonstrated that performance parameters are improved with fluid ring actuator. Research limitations/implications Fluid ring actuator can be affected by environmental pressure and temperature. Therefore, freezing and boiling temperature of the fluid should be considered in system designation. Practical implications Fluid ring servomechanism can be used as ACS in rigid satellites. This actuator is compared by CMG, the prevalent actuator. It has less displacement attitude maneuver. Originality/value The results provide the feasibility and advantages of using fluid rings as satellite ACS. The quaternion error controller is used for this model to enhance its performance.

Disturbance observer control method in SGMSCMG

2014 ◽  
Vol 229 (11) ◽  
pp. 1998-2006 ◽  
Author(s):  
Cong Peng ◽  
Jinji Sun
Keyword(s):  
Disturbance Observer ◽  
Control Method ◽  
Controller Design ◽  
Magnetic Bearing ◽  
Observer Design ◽  
Control Moment ◽  
Parameter Variations ◽  
Simulation And Experiment ◽  
The Stability ◽  
Control Moment Gyro

To restrain disturbances produced by parameter variations and external disturbances in axial magnetic bearing in the application of single-gimbal magnetically suspended control moment gyro (SGMSCMG), a disturbance observer control method is proposed, which integrated [Formula: see text] controller and disturbance observer. This method considers parameter variations of the axial magnetic bearing and the effect of gimbals on axial magnetic bearing. Consequently, the state space equation is changed to include the disturbances. Then the robust controller is designed, which includes the disturbance observer design and robust [Formula: see text] controller design. The stability analysis is given for the proposed controller. Simulation and experiment results on the SGMSCMG verified the correctness of the proposed method.

Kinematics Study on an Omnidirectional Mobile Robot with MY Wheels

ROBOT ◽  
2012 ◽  
Vol 34 (2) ◽  
pp. 144 ◽  
Author(s):  
Changlong YE ◽  
Huaiyong LI ◽  
Shugen MA ◽  
Huichao NI
Keyword(s):  
Mobile Robot ◽  
Omnidirectional Mobile Robot

Design of potential IKK-β inhibitors using molecular docking and molecular dynamics techniques for their anti-cancer potential

2020 ◽  
Vol 16 ◽  
Author(s):  
Salam Pradeep Singh ◽  
Iftikar Hussain ◽  
Bolin Kumar Konwar ◽  
Ramesh Chandra Deka ◽  
Chingakham Brajakishor Singh
Keyword(s):  
Molecular Dynamics ◽  
Molecular Docking ◽  
Md Simulation ◽  
Inflammatory Diseases ◽  
Binding Free Energy ◽  
Anti Cancer ◽  
Dietary Phytochemicals ◽  
Toxicity Analysis ◽  
The Stability ◽  
Stable Trajectory

Aim and Objective: To evaluate a set of seventy phytochemicals for their potential ability to bind the inhibitor of nuclear factor kappaB kinase beta (IKK-β) which is a prime target for cancer and inflammatory diseases. Materials and Methods: Seventy phytochemicals were screened against IKK-β enzyme using DFT-based molecular docking technique and the top docking hits were carried forward for molecular dynamics (MD) simulation protocols. The adme-toxicity analysis was also carried out for the top docking hits. Results: Sesamin, matairesinol and resveratrol were found to be the top docking hits with a total score of -413 kJ/mol, -398.11 kJ/mol and 266.73 kJ/mol respectively. Glu100 and Gly102 were found to be the most common interacting residues. The result from MD simulation observed a stable trajectory with a binding free energy of -107.62 kJ/mol for matairesinol, -120.37 kJ/mol for sesamin and -40.56 kJ/mol for resveratrol. The DFT calculation revealed the stability of the compounds. The ADME-Toxicity prediction observed that these compounds fall within the permissible area of Boiled-Egg and it does not violate any rule for pharmacological criteria, drug-likeness etc. Conclusion: The study interprets that dietary phytochemicals are potent inhibitors of IKK-β enzyme with favourable binding affinity and less toxic effects. In fact, there is a gradual rise in the use of plant-derived molecules because of its lesser side effects compared to chemotherapy. The study has also provided an insight by which the phytochemicals inhibited the IKK-β enzyme. The investigation would also provide in understanding the inhibitory mode of certain dietary phytochemicals in treating cancer.

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