Hybrid Position/Force Control for a RRR 3-DoF Manipulator

2011 ◽  
Vol 48-49 ◽  
pp. 589-592 ◽  
Author(s):  
Shi Xiang Tian ◽  
Sheng Ze Wang
Keyword(s):  
Force Control ◽  
Free Space ◽  
High Performance ◽  
Degree Of Freedom ◽  
End Effector ◽  
Robot Trajectory ◽  
Simulation Results ◽  
Trajectory Following ◽  
Three Degree Of Freedom

In this paper, a novel hybrid position/force controller has been proposed for a three degree of freedom (3-DOF) of robot trajectory following that is required to switch between position and force control. The whole controller consists of two components: a positional controller and a force controller. Depending on whether the end-effector is in free space or in contact with the environments during work, the two subcontrollers run simultaneously to guide the manipulator tracking in free space and constraint environments. After the principle and stability of the controller are briefly analyzed, simulation results verify that the proposed controller attains a high performance.

scholarly journals Optimization of Dynamic Task Location within a Manipulator’s Workspace for the Utilization of the Minimum Required Joint Torques

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 288
Author(s):  
Adam Wolniakowski ◽  
Charalampos Valsamos ◽  
Kanstantsin Miatliuk ◽  
Vassilis Moulianitis ◽  
Nikos Aspragathos
Keyword(s):  
High Performance ◽  
Human Robot Interaction ◽  
Optimal Position ◽  
End Effector ◽  
Joint Torques ◽  
Dynamic Task ◽  
Arbitrary Position ◽  
Simulation Results ◽  
Set Up ◽  
Task Placement

The determination of the optimal position of a robotic task within a manipulator’s workspace is crucial for the manipulator to achieve high performance regarding selected aspects of its operation. In this paper, a method for determining the optimal task placement for a serial manipulator is presented, so that the required joint torques are minimized. The task considered comprises the exercise of a given force in a given direction along a 3D path followed by the end effector. Given that many such tasks are usually conducted by human workers and as such the utilized trajectories are quite complex to model, a Human Robot Interaction (HRI) approach was chosen to define the task, where the robot is taught the task trajectory by a human operator. Furthermore, the presented method considers the singular free paths of the manipulator’s end-effector motion in the configuration space. Simulation results are utilized to set up a physical execution of the task in the optimal derived position within a UR-3 manipulator’s workspace. For reference the task is also placed at an arbitrary “bad” location in order to validate the simulation results. Experimental results verify that the positioning of the task at the optimal location derived by the presented method allows for the task execution with minimum joint torques as opposed to the arbitrary position.

Three-Degree-of-Freedom Parallel Robot Arm

2006 ◽  
Author(s):  
Martin Hosek ◽  
Michael Valasek ◽  
Jairo Moura
Keyword(s):  
Parallel Robot ◽  
Degree Of Freedom ◽  
Motion Path ◽  
Angular Orientation ◽  
Robot Arm ◽  
Flat Panel Display ◽  
End Effector ◽  
Cluster Tools ◽  
Manufacturing Applications ◽  
Three Degree Of Freedom

This paper presents single- and dual-end-effector configurations of a planar three-degree of freedom parallel robot arm designed for automated pick-place operations in vacuum cluster tools for semiconductor and flat-panel-display manufacturing applications. The basic single end-effector configuration of the arm consists of a pivoting base platform, two elbow platforms and a wrist platform, which are connected through two symmetric pairs of parallelogram mechanisms. The wrist platform carries an end-effector, the position and angular orientation of which can be controlled independently by three motors located at the base of the robot. The joints and links of the mechanism are arranged in a unique geometric configuration which provides a sufficient range of motion for typical vacuum cluster tools. The geometric properties of the mechanism are further optimized for a given motion path of the robot. In addition to the basic symmetric single end-effector configuration, an asymmetric costeffective version of the mechanism is derived, and two dual-end-effector alternatives for improved throughput performance are described. In contrast to prior attempts to control angular orientation of the end-effector(s) of the conventional arms employed currently in vacuum cluster tools, all of the motors that drive the arm can be located at the stationary base of the robot with no need for joint actuators carried by the arm or complicated belt arrangements running through the arm. As a result, the motors do not contribute to the mass and inertia properties of the moving parts of the arm, no power and signal wires through the arm are necessary, the reliability and maintenance aspects of operation are improved, and the level of undesirable particle generation is reduced. This is particularly beneficial for high-throughput applications in vacuum and particlesensitive environments.

Parametric Design of a Spherical Eight-Bar Linkage Based on a Spherical Parallel Manipulator

2008 ◽  
Vol 1 (1) ◽  
Author(s):  
Gim Song Soh ◽  
J. Michael McCarthy
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Parametric Design ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
End Effector ◽  
Arbitrary Base ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator

This paper presents a procedure that determines the dimensions of two constraining links to be added to a three degree-of-freedom spherical parallel manipulator so that it becomes a one degree-of-freedom spherical (8, 10) eight-bar linkage that guides its end-effector through five task poses. The dimensions of the spherical parallel manipulator are unconstrained, which provides the freedom to specify arbitrary base attachment points as well as the opportunity to shape the overall movement of the linkage. Inverse kinematics analysis of the spherical parallel manipulator provides a set of relative poses between all of the links, which are used to formulate the synthesis equations for spherical RR chains connecting any two of these links. The analysis of the resulting spherical eight-bar linkage verifies the movement of the system.

Determination of the Singularity Loci of Spherical Three-Degree-of-Freedom Parallel Manipularors

1992 ◽  
Author(s):  
Clément M. Gosselin ◽  
Jaouad Sefrioui
Keyword(s):  
Graphical Representation ◽  
Jacobian Matrix ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
End Effector ◽  
Cartesian Space ◽  
Singularity Locus ◽  
Three Degree Of Freedom ◽  
Analytical Expressions

Abstract In this paper, an algorithm for the determination of the singularity loci of spherical three-degree-of-freedom parallel manipulators with prismatic atuators is presented. These singularity loci, which are obtained as curves or surfaces in the Cartesian space, are of great interest in the context of kinematic design. Indeed, it has been shown elsewhere that parallel manipulators lead to a special type of singularity which is located inside the Cartesian workspace and for which the end-effector becomes uncontrollable. It is therfore important to be able to identify the configurations associated with theses singularities. The algorithm presented is based on analytical expressions of the determinant of a Jacobian matrix, a quantity that is known to vanish in the singular configurations. A general spherical three-degree-of-freedom parallel manipulator with prismatic actuators is first studied. Then, several particular designs are investigated. For each case, an analytical expression of the singularity locus is derived. A graphical representation in the Cartesian space is then obtained.

The Workspace of a General Geometry Planar Three-Degree-of-Freedom Platform-Type Manipulator

1993 ◽  
Vol 115 (2) ◽  
pp. 269-276 ◽  
Author(s):  
G. R. Pennock ◽  
D. J. Kassner
Keyword(s):  
Degree Of Freedom ◽  
Arbitrary Orientation ◽  
End Effector ◽  
The Absolute ◽  
Position Problem ◽  
General Geometry ◽  
Three Degree Of Freedom ◽  
Insight Into

This paper focuses on the direct workspace problems of a general geometry fully-parallel-actuated, planar three-degree-of-freedom platform-type manipulator. A set of equations are presented that determine the workspace as a function of the platform orientation. The formulation is governed by the solution to the inverse position problem of the manipulator. The reachable positions of the end-effector point, for a specified platform orientation, are analyzed. To illustrate the concepts, a practical example is included where the end-effector is required to move a cup filled with water. Then the platform orientation, for a specified location of the end-effector point, is studied. If an arbitrary orientation is possible, the specified location of the end-effector point is said to be within the primary workspace. The paper includes a detailed discussion of the total primary workspaces of the manipulator. The approach adopted here is to regard the manipulator as a combination of three planar, three-revolute open chains. For the sake of completeness, the influence of special manipulator geometry on the workspace is also discussed. Finally, the paper includes the conditions that cause stationary configurations of the manipulator. Insight into these undesirable configurations is provided by a study of the location of the absolute instant center of the platform.

Robot force control without dynamic model: theory and experiments

Robotica ◽  
2012 ◽  
Vol 31 (1) ◽  
pp. 149-171 ◽  
Author(s):  
Juan C. Rivera-Dueñas ◽  
Marco A. Arteaga-Pérez
Keyword(s):  
Model Theory ◽  
Contact Surface ◽  
Force Control ◽  
Control Algorithm ◽  
Velocity Measurements ◽  
Unit Quaternion ◽  
End Effector ◽  
Simulation Results ◽  
The Many ◽  
Theory And Experiments

SUMMARYAmong the many challenges to deal with, when a robot is interacting with its environment, friction at the contact surface and/or at the joints is one of the most important to be considered. In this paper we propose a control algorithm for the tracking of position and force (unconstrained orientation case only) of a manipulator end-effector that does not require the robot model for implementation. This characteristic has the advantage of making it capable to compensate friction effects without any previous estimation. Furthermore, no velocity measurements are needed, and the unit quaternion is employed for orientation control. Experimental and simulation results are provided.

Kinematic Analysis of Robotic Bevel-Gear Trains

1984 ◽  
Vol 106 (3) ◽  
pp. 371-375 ◽  
Author(s):  
F. Freudenstein ◽  
R. W. Longman ◽  
C.-K. Chen
Keyword(s):  
Kinematic Analysis ◽  
Industrial Robot ◽  
General Procedure ◽  
Bevel Gear ◽  
Degree Of Freedom ◽  
Gear Train ◽  
End Effector ◽  
Gear Trains ◽  
Three Degree Of Freedom

A general procedure has been developed for the kinematic analysis of complex bevel-gear trains in which the motion of the arm can be of mobility two or greater (i.e. the arm can rotate about two or more nonparallel, intersecting axes). The analysis of a three-degree-of-freedom gear train used in guiding the motion of the end effector of a recently developed industrial robot is described in detail.

Precision force control of an underactuated stance leg exoskeleton for human performance augmentation

2021 ◽  
pp. 095965182110405
Author(s):  
Shan Chen ◽  
Tenghui Han ◽  
Fangfang Dong ◽  
Lei Lu ◽  
Haijun Liu ◽  
...  
Keyword(s):  
Force Control ◽  
Lower Limb ◽  
High Performance ◽  
Human Performance ◽  
Interaction Force ◽  
Adaptive Robust Control ◽  
Integrated System ◽  
Degree Of Freedom ◽  
Human Machine Interaction ◽  
Lower Limb Exoskeleton

Lower limb exoskeleton which augments the human performance is a wearable human–machine integrated system used to assist people carrying heavy loads. Recently, underactuated lower limb exoskeleton systems with some passive joints become more and more attractive due to the advantages of smaller weight, lower system energy consumption and lower cost. However, because of the less of control inputs, the existed control methods of fully actuated exoskeletons cannot be extended to underactuated systems, which makes the robust controller design of underactuated lower limb exoskeletons becomes more challenged. This article focuses on the high-performance human–machine interaction force control design of underactuated lower limb exoskeletons with passive ankle joint. In order to solve the reduction of control inputs, the holonomic constraint from the wearer is considered, which help transform the dynamics of 3-degree-of-freedom underactuated exoskeleton in joint space into a 2-degree-of-freedom fully actuated system in Cartesian space. A two-level interaction force controller using adaptive robust control algorithm is proposed to effectively address the negative effect of various model uncertainties and external disturbances. In order to facilitate the control parameter selection, a gain tuning method is also presented. Comparative simulations are carried out, which indicate that the proposed two-level interaction force controller achieves smaller interaction force and better robust performance to various modeling errors and disturbances.

Modeling and Experimental Evaluation of Asymmetric Pantograph Dynamics

1988 ◽  
Vol 110 (2) ◽  
pp. 168-174 ◽  
Author(s):  
S. D. Eppinger ◽  
D. N. O’Connor ◽  
W. P. Seering ◽  
D. N. Wormley
Keyword(s):  
High Performance ◽  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Dynamic Testing ◽  
Dynamic Performance ◽  
Performance Model ◽  
Degree Of Freedom ◽  
Additional Degree ◽  
Three Degree Of Freedom ◽  
Two Degree Of Freedom

High-performance pantograph design requires control of pantograph dynamic performance. Many pantograph dynamic models developed to aid in the design process have employed two degrees of freedom, one for the head mass and one for the frame. In this paper, the applicability of these models to symmetric and asymmetric pantograph designs is reviewed. Two degree-of-freedom models have been shown to be appropriate to represent a number of symmetric pantograph designs. To represent the asymmetric designs considered in this paper, an additional degree of freedom representing frame dynamics has been introduced to yield a three degree-of-freedom nonlinear dynamic performance model. The model has been evaluated with experimental data obtained from laboratory dynamic testing of an asymmetric pantograph.

Impedance Control of Space Robots Using Passive Degrees of Freedom in Controller Domain

2005 ◽  
Vol 127 (4) ◽  
pp. 564-578 ◽  
Author(s):  
Pushpraj Mani Pathak ◽  
Amalendu Mukherjee ◽  
Anirvan Dasgupta
Keyword(s):  
Force Control ◽  
Degrees Of Freedom ◽  
Impedance Control ◽  
Space Structure ◽  
Degree Of Freedom ◽  
Robotic Systems ◽  
Stable Method ◽  
Space Robots ◽  
End Effector ◽  
Control Schemes

Impedance control is an efficient and stable method of providing trajectory and force control in robotic systems. The procedure by which the impedance of the manipulator is changed is a very important aspect in the design of impedance based control schemes. In this work, a scheme is presented in which the control of impedance at the interface of the end effector and the space structure is achieved by introduction of a passive degree of freedom (DOF) in the controller of the robotic system. The impedance is shown to depend upon a compensation gain for the dynamics of the passive DOF. To illustrate the methodology, an example of a two DOF planer space robot is considered.

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