Slip Analysis for a Wheeled Mobile Manipulator

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Tao Song ◽  
Fengfeng (Jeff) Xi ◽  
Shuai Guo ◽  
Xiaowei Tu ◽  
Xianhua Li
Keyword(s):  
Reaction Force ◽  
Mobile Manipulator ◽  
Centrifugal Forces ◽  
End Effector ◽  
Industrial Manipulator ◽  
The Third ◽  
Aircraft Manufacturing ◽  
First Case ◽  
Inertia Forces ◽  
Climbing Stairs

A method is presented for slip analysis of a wheeled mobile manipulator. The said system consists of an industrial manipulator mounted on a mobile platform performing aircraft manufacturing tasks. Unlike tracked/legged mobile robots that may slip when negotiating slopes or climbing stairs, a wheeled mobile manipulator may slip resulting from the manipulator movement or the forces from the end-effector during fastening. Slip analysis is crucial to ensure pose accuracy for operation. In this study, first a universal friction constraint is used to derive the slip condition of the system. Three cases are considered, with the first case considering the reaction force in relation to the stand-off distance between the mobile manipulator and the workpiece. The second case deals with the joint speeds to investigate the effect of coupling terms including centrifugal forces and gyroscopic moments on slip. The third case deals with the joint accelerations to investigate the effect of inertia forces and moments on slip. Simulations and experiments are carried out to verify the proposed method.

Design, Analysis, and Applications of Mobile Manipulators

2018 ◽  
pp. 26-65
Author(s):  
Tao Song ◽  
Feng Feng Xi ◽  
Shuai Guo
Keyword(s):  
Reaction Force ◽  
Mobile Platform ◽  
Mobile Manipulator ◽  
Work Piece ◽  
Mobile Manipulators ◽  
Robot Arm ◽  
The Third ◽  
First Case ◽  
Coupling Terms ◽  
Inertia Forces

Presented in this chapter is a method for design and analysis of a mobile manipulator. The wrench induced by the movement of the robot arm will cause system tip-over or slip. In tip-over analysis, three cases are considered. The first case deals with the effect of the link weights and tip payload on the horizontal position of the CG. The second case deals with the effect of the joint speeds through the coupling terms including centrifugal forces and gyroscopic moments. The third case deals with the effect of the joint accelerations through the inertia forces and moments. In slip analysis, the first case considers the reaction force in relation to the stand-off distance between system and work-piece. The second and third cases investigate the effects of the joint speeds and accelerations. Then, the mobile platform is optimized to have maximum tip-over stability which optimizes the placement of the robot arm and accessory on the mobile platform. The effectiveness of the proposed method is demonstrated.

Simplified Tele-Operation of Mobile-Manipulator Systems Using Knowledge of Their Singular Configurations

2009 ◽  
Author(s):  
Michael C. Frejek ◽  
Scott B. Nokleby
Keyword(s):  
Mobile Manipulator ◽  
End Effector ◽  
Control Approach ◽  
Singular Configurations ◽  
The Third ◽  
Preliminary Version ◽  
Optimization Routine ◽  
Position And Orientation ◽  
Singular Configuration ◽  
Mobile Base

An algorithm for the simplified tele-operation of a mobile-manipulator system is presented. It allows for unified, intuitive, and coordinated control. Unlike other approaches, the mobile-manipulator system is modelled and controlled as two separate entities rather than as a whole. The algorithm consists of three states. In the first state, a joystick is used to freely control the manipulator’s position and orientation. The second state occurs when the manipulator approaches a singular configuration. This causes the mobile base to proceed in such a way as to keep the end-effector moving in its last direction. This is done through the use of a simple optimization routine. The third state is triggered by the user: once the end-effector is in the desired position, the mobile base and manipulator both move with respect to one another keeping the end-effector stationary and placing the manipulator into an ideal configuration. The proposed algorithm avoids the problems of algorithmic singularities and simplifies the control approach. A preliminary version of the algorithm has been implemented on the Jasper mobile-manipulator system with success.

Penile Lymphoepithelioma-Like Carcinoma: A Rare Case With PD-L1 Expression

2021 ◽  
pp. 106689692098834
Author(s):  
Raquel Machado-Neves ◽  
Bernardo Teixeira ◽  
Elsa Fonseca ◽  
Pedro Valente ◽  
Joaquim Lindoro ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Tumor Cells ◽  
Rare Case ◽  
Malignant Tumors ◽  
Squamous Cell Carcinomas ◽  
The Third ◽  
The Past ◽  
First Case ◽  
Lymphoplasmacytic Infiltrate

Most malignant tumors of the penis are squamous cell carcinomas (SCC), being divided in 2 groups, one human papillomavirus (HPV)-related and another non-HPV-related, with lymphoepithelioma-like carcinoma (LELC) being one of the rarest HPV-related SCC. In this article, we report a case of a 50-year-old man who presented testicular swelling and pain for the past 3 months. A penile mass was identified, and the patient was submitted to a total penectomy. The penectomy specimen showed an ulcerated lesion at the glans reaching the cavernous bodies. Microscopic examination showed undifferentiated epithelial cells with syncytial growth pattern mix with a dense lymphoplasmacytic infiltrate, consistent with LELC. The tumor cells expressed p16 and all 3 different clones of PDL1 (22C3, SP263, and SP142). The patient is alive and well with a follow-up of 3 months. To our knowledge, this is the third LELC of the penis reported in literature and the first case reported with PDL1 expression.

scholarly journals A Novel Coaxial Balance Mechanism for Reciprocating Piston Engines

2021 ◽  
Vol 11 (12) ◽  
pp. 5647
Author(s):  
Nanxiang Guan ◽  
Ao Wang ◽  
Yongpeng Gu ◽  
Zhifeng Xie ◽  
Ming Zhou
Keyword(s):  
Reaction Force ◽  
Vibration Reduction ◽  
Second Order ◽  
Root Mean Square Velocity ◽  
First Order ◽  
Support Reaction ◽  
Cylinder Piston ◽  
Test Points ◽  
Balance Mechanism ◽  
Inertia Forces

Vibration is an important issue faced by reciprocating piston engines, and is caused by reciprocating inertia forces of the piston set. To reduce the vibration without changing the main structure and size of the original engine, we proposed a novel coaxial balance mechanism design based on a compact unit body. By introducing a second-order balance mass, this mechanism can significantly increase the efficiency of vibration reduction. The proposed mechanism can effectively balance the first-order and second-order inertia forces with the potential of balancing high-order inertia forces. To accurately determine the second-order balance mass, a closed-form method was developed. Simulation results with a single-cylinder piston DK32 engine demonstrate the effectiveness and advantage of the proposed mechanism. At a crankshaft speed of 2350 r/min, compared with the first-order balance device, the average root mean square velocity of the test points on the engine’s cylinder was reduced by 97.31%, and the support reaction force was reduced by 96.54%.

Pricing of Connected and Autonomous Vehicles in Mixed-Traffic Networks

2021 ◽  
pp. 036119812098585
Author(s):  
Paolo Delle Site
Keyword(s):  
Autonomous Vehicles ◽  
Marginal Cost ◽  
User Behavior ◽  
Social Planner ◽  
Traffic Networks ◽  
Mixed Traffic ◽  
The Third ◽  
First Case ◽  
Marginal Cost Pricing ◽  
The Social

For networks with human-driven vehicles (HDVs) only, pricing with arc-specific tolls has been proposed to achieve minimization of travel times in a decentralized way. However, the policy is hardly feasible from a technical viewpoint without connectivity. Therefore, for networks with mixed traffic of HDVs and connected and autonomous vehicles (CAVs), this paper considers pricing in a scenario where only CAVs are charged. In contrast to HDVs, CAVs can be managed as individual vehicles or as a fleet. In the latter case, CAVs can be routed to minimize the travel time of the fleet of CAVs or that of the entire fleet of HDVs and CAVs. We have a selfish user behavior in the first case, a private monopolist behavior in the second, a social planner behavior in the third. Pricing achieves in a decentralized way the social planner optimum. Tolls are not unique and can take both positive and negative values. Marginal cost pricing is one solution. The valid toll set is provided, and tolls are then computed according to two schemes: one with positive tolls only and minimum toll expenditure, and one with both tolls and subsidies and zero net expenditure. Convergent algorithms are used for the mixed-behavior equilibrium (simplicial decomposition algorithm) and toll determination (cutting plane algorithm). The computational experience with three networks: a two-arc network representative of the classic town bypass case, the Nguyen-Dupuis network, and the Anaheim network, provides useful policy insight.

Overview of recent cases before the Court of Justice of the European Union (November 2020-March 2021)

2021 ◽  
pp. 138826272110092
Author(s):  
Pauline Melin
Keyword(s):  
Parental Leave ◽  
The European Union ◽  
Framework Agreement ◽  
The Third ◽  
Court Of Justice ◽  
Rest Periods ◽  
First Case ◽  
Family Benefits ◽  
Grand Chamber ◽  
Italian Legislation

In this reporting period (November 2020-March 2021), five cases will be presented. The first case is INPS v WS (C-302/19), dealing with the Italian legislation that excludes Single Permit holders from receiving family benefits for their family members residing in a third country. In the second report, two cases rendered on the same day by the Grand Chamber of the Court are discussed. In D.J. v Radiotelevizija Slovenija (C-344/19) and RJ v Stadt Offenbach am Main (C-580/19), the Court clarified the circumstances under which periods of stand-by time could be considered as ‘working time’ or, alternatively, ‘rest periods’ under Directive 2003/88. XI v Caisse pour l’avenir des enfants (C-129/20) is the third case reported. It concerns an interpretation of the Framework Agreement on parental leave in the light of the Luxembourg legislation, which requires parents to be employed at the time of their child’s birth to benefit from parental leave. Finally, the case report ends with VL v Szpital Kliniczny im. dra J. Babińskiego Samodzielny Publiczny Zakład Opieki Zdrowotnej w Krakowie (C-16/19), a case of discrimination on grounds of disability.

Time suboptimal control of industrial manipulators along specified paths while keeping an end-effector orientation unchanged

Robotica ◽  
2003 ◽  
Vol 21 (2) ◽  
pp. 153-161 ◽  
Author(s):  
S. Kilicaslan ◽  
Y. Ercan
Keyword(s):  
Suboptimal Control ◽  
Time Step ◽  
End Effector ◽  
Industrial Manipulator ◽  
Industrial Manipulators ◽  
Angular Velocities ◽  
System Equations ◽  
Six Degree Of Freedom ◽  
Time Suboptimal Control

A method for the time suboptimal control of an industrial manipulator that moves along a specified path while keeping its end-effector orientation unchanged is proposed. Nonlinear system equations that describe the manipulator motion are linearized at each time step along the path. A method which gives control inputs (joint angular velocities) for time suboptimal control of the manipulator is developed. In the formulation, joint angular velocity and acceleration limitations are also taken into consideration. A six degree of freedom elbow type manipulator is used in a case study to verify the method developed.

Cooperation and Null-Space Control of Networked Omni-Directional Mobile Manipulators

2020 ◽  
Author(s):  
Michael John Chua ◽  
Yen-Chen Liu
Keyword(s):  
Degrees Of Freedom ◽  
Null Space ◽  
Kinematic Model ◽  
Mobile Manipulator ◽  
Main Task ◽  
Mobile Manipulators ◽  
Robot Arm ◽  
Task Space ◽  
End Effector ◽  
Mobile Base

Abstract This paper presents cooperation and null-space control for networked mobile manipulators with high degrees of freedom (DOFs). First, kinematic model and Euler-Lagrange dynamic model of the mobile manipulator, which has an articulated robot arm mounted on a mobile base with omni-directional wheels, have been presented. Then, the dynamic decoupling has been considered so that the task-space and the null-space can be controlled separately to accomplish different missions. The motion of the end-effector is controlled in the task-space, and the force control is implemented to make sure the cooperation of the mobile manipulators, as well as the transportation tasks. Also, the null-space control for the manipulator has been combined into the decoupling control. For the mobile base, it is controlled in the null-space to track the velocity of the end-effector, avoid other agents, avoid the obstacles, and move in a defined range based on the length of the manipulator without affecting the main task. Numerical simulations have been addressed to demonstrate the proposed methods.

Low-Grade Mucosa-Associated Lymphoid Tissue Lymphoma Involving the Kidney: Report of 3 Cases and Review of the Literature

2006 ◽  
Vol 130 (1) ◽  
pp. 86-89 ◽  
Author(s):  
Libo Qiu ◽  
Pamela D. Unger ◽  
Robert W. Dillon ◽  
James A. Strauchen
Keyword(s):  
Lymphoid Tissue ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Lymphoid Cells ◽  
Low Grade ◽  
The Third ◽  
First Case ◽  
Abundant Cytoplasm ◽  
History Of

Abstract Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue involving the kidney is rare. We report a series of 3 cases. The first case occurred in an 83-year-old woman who presented with back pain. The second case was a 53-year-old man with a history of sarcoidosis who was found, in the course of evaluation of sarcoidosis, to have a right renal mass. The third case occurred in a 72-year-old man who had a history of periorbital mucosa–associated lymphoid tissue lymphoma and had been treated with surgery and radiation 1 year prior to this presentation. Histologically, all 3 patients showed infiltrate of uniform small-to-medium–sized lymphocytes with irregular nuclear contours and abundant cytoplasm resembling centrocytes or monocytoid lymphoid cells. The first patient received chemotherapy without complications. The second patient underwent a partial nephrectomy and was asymptomatic at the subsequent follow-up. The third patient developed a pulmonary embolism following nephrectomy, and further follow-up is not available.

Stability control for end effect of mobile manipulator in uneven terrain based on active disturbance rejection control

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chuang Cheng ◽  
Hui Zhang ◽  
Hui Peng ◽  
Zhiqian Zhou ◽  
Bailiang Chen ◽  
...  
Keyword(s):  
Disturbance Rejection ◽  
Control Method ◽  
External Disturbance ◽  
Stability Control ◽  
Mobile Manipulator ◽  
Active Disturbance Rejection Control ◽  
End Effector ◽  
Content Type ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control

Purpose When the mobile manipulator is traveling on an unconstructed terrain, the external disturbance is generated. The load on the end of the mobile manipulator will be affected strictly by the disturbance. The purpose of this paper is to reject the disturbance and keep the end effector in a stable pose all the time, a control method is proposed for the onboard manipulator. Design/methodology/approach In this paper, the kinematics and dynamics models of the end pose stability control system for the tracked robot are built. Through the guidance of this model information, the control framework based on active disturbance rejection control (ADRC) is designed, which keeps the attitude of the end of the manipulator stable in the pitch, roll and yaw direction. Meanwhile, the control algorithm is operated with cloud computing because the research object, the rescue robot, aims to be lightweight and execute work with remote manipulation. Findings The challenging simulation experiments demonstrate that the methodology can achieve valid stability control performance in the challenging terrain road in terms of robustness and real-time. Originality/value This research facilitates the stable posture control of the end-effector of the mobile manipulator and maintains it in a suitable stable operating environment. The entire system can normally work even in dynamic disturbance scenarios and uncertain nonlinear modeling. Furthermore, an example is given to guide the parameter tuning of ADRC by using model information and estimate the unknown internal modeling uncertainty, which is difficult to be modeled or identified.

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