3-DOF Parallel Mechanism Research Articles

Inverse kinematic and dynamic analysis of a 3-DOF parallel mechanism

Inverse kinematic and dynamic analysis of a 3-DOF parallel mechanism

Three DOF parallel link mechanism utilizing smooth impact drive mechanism

For a wide range of purposes, a compact and smart positioning stage is in strong demand. Our final goal is to fabricate a positioning mechanism that possesses multi-degrees of freedom, a wide movable area, dexterity, rigidity, and high speed. To meet most of requirements, i.e., except that of a wide movable area, a parallel mechanism is superior to a serial link mechanism. However, a lack of smart actuators has previously resulted in a large and complicated construction of a parallel mechanism. A purpose of this paper is to propose a new parallel link that utilizes a smart actuator called smooth impact drive mechanism (SIDM), and to verify its advantage for a smart and compact positioning stage. The SIDM actuator is an interesting mechanism that achieves a long stroke with fine positioning resolution. This paper treats a three DOF stage containing three SIDM actuators and a two-dimensional positioning sensor. The first operation test was carried out, and it was confirmed that a position control was successful. The average deviation was 18.6 μm and the standard deviation was 9.31 μm. As another trial, a circle 3.0 mm in diameter was successfully drawn. These values were insufficient for the SIDM actuator that has potentially nanometer-level resolution. The rough positioning resolution seems to be due to inferior driving method and mechanical ricketiness of the joints. In the near future, high speed and accurate positioning control could be realized with overcoming these problems.

Vision System for Micromanipulation

Recently, in connection with down-sizing of manipulated objects in fields such as biology and medical treatment, the establishment of dexterous micromanipulation is crucial. Dexterous micro manipulation using a two finger microhand with 12-DOF and an optical microscope has been developed for applications such as assembling micromachines and manipulating cells and microbes. Basic experiments showed two problems, a more compact hand mechanism fit in the limited microscope workspace and less focusing work for an operator. A 3-DOF parallel mechanism is designed for a new finger module. To decrease focusing during manipulation, an autofocusing and tracking mechanism is developed using microscope image data. The focusing algorithm uses color and brightness to make tracking smooth. Experiments include tracking a moving object and recognizing and localizing a target in a focal plane.

2323 6 自由度パラレルメカニズムの校正に関する研究

2323 6 自由度パラレルメカニズムの校正に関する研究

610 特異点を考慮した 6 自由度空間パラレル機構の動的解析

610 特異点を考慮した 6 自由度空間パラレル機構の動的解析

2A1-F01 3 リンク-6 自由度型パラレルメカニズムの内力を利用した位置制御

2A1-F01 3 リンク-6 自由度型パラレルメカニズムの内力を利用した位置制御

203 ACサーボモータを用いた6自由度パラレルメカニズムロボットの運動特性(GS.1 運動機構・メカトロニクス)

203 ACサーボモータを用いた6自由度パラレルメカニズムロボットの運動特性(GS.1 運動機構・メカトロニクス)

Static balancing of spatial three-degree-of-freedom parallel mechanisms

The static balancing of spatial three-degree-of-freedom (3-dof) parallel mechanisms or manipulators with revolute actuators using counterweights or springs is studied in this paper. The expressions for the position vector of the center of mass and the total potential energy of the mechanism are first obtained. Then, the kinematic constraint equations of the mechanism are introduced in order to eliminate some of the dependent variables from the expressions. Finally, the conditions for the static balancing of the mechanism are derived from the resulting expressions. Two examples corresponding to the two balancing methodologies are given in order to illustrate the results.

Intelligent Motion Task Planning of Redundant Parallel Manipulator.

In this study, a robot that utilizes a parallel mechanism at parts of its body is proposed.The robot combines locomotion and manipulation, and consists mainly of four units of three degree of freedom (hereafter called DOF) parallel mechanism with linear actuators and two grippers attached to both sides of its body.The robot has high redundancy with 14-DOF without grippers.The purpose of this study is to realize the"intelligent motion"in the redundant parallel manipulator that performs the basic motion of the proposed robot.The robot determines its motion while considering its redundancy and improves it using actuator information derived from the motion.First, we analyze the kinematics and statics about the parallel manipulator, and show a method to optimize the solution of inverse kinematics that includes the redundancy problem.Next, we discuss the intelligent motion task planning of the parallel manipulator using actuator information.Two methods are proposed based on the optimization of inverse kinematics.One optimizes the motion by iteration.The other optimizes the motion successively in continuous motion tasks.Finally, the effectiveness of the proposed methods is verified experimentally.

Static balancing of 3-DOF planar parallel mechanisms

The static balancing of planar 3-DOF parallel mechanisms is addressed in this paper. Static balancing is defined as the set of conditions on mechanism dimensional and inertial parameters which, when satisfied, ensure that the weight of the links does not produce any torque (or force) at the actuators for any configuration of the mechanism, under static conditions. For the mechanisms studied here, conditions for static balancing are obtained, and it is shown that balancing is generally possible, even when the dimensional parameters are imposed, which is a useful property since dimensional parameters are usually obtained from kinematic design or optimization. Then, the conditions for the static balancing of the same mechanisms are derived for designs in which elastic elements are included. Finally, examples of balanced mechanisms are given. A dynamic study is performed.

KINEMATIC ANALYSIS OF A GENERAL DOUBLE-TRIPOD PARALLEL MANIPULATOR

The kinematics of a general double-tripod manipulator is presented. The double tripod manipulator is based on a spatial three-degrees-of-freedom (3-DOF) parallel mechanism. The device possesses a moving platform, a fixed platform, and three legs. Each leg comprises kinematically similar rotary, spherical, and rotary joints. The kinematic model of the mechanism used here consists of a generalized, non-reflective mechanism. The mobility of the mechanism is examined, and solutions to the forward and inverse kinematics problems are presented. It is also shown that special geometries of the mechanism result in closed-form solutions for both the forward and inverse kinematics. Numerical results are presented for the general case and also for the simplified case, and algorithm speed is examined.

Intelligent Motion Task Planning of Redundant Parallel Manipulator.

In this study, a robot using a parallel mechanism as parts of the body is proposed. robot integrates locomotion and manipulation, and mainly consists of four 3 DOF parallel mechanism with linear actuators and two grippers attached to both sides of the body. The robot has high redundancy with 14-DOF without grippers. purpose of this study is to realize Intelligent Motion of the redundant parallel manipulator that performs basic motion of the proposed robot. robot determines the motion with considering its redundancy and improves it by using actuator informations that are taken in through the motion. First, this paper treats the analysis of kinematics and statics about the parallel manipulator, and shows the method to optimize the solution of inverse kinematics that includes redundancy problem. Next, the intelligent motion task planning of the parallel manipulator using actuator informations is mentioned. Two methods are proposed based on optimization of inverse kinematics. One optimizes the motion by iterative exercise. other optimizes the motion successively in continuous motion tasks. Finally, the effectiveness of the proposed methods were verified through the experiment.

Synthesis of Multiple DOF Parallel Mechanism Satisfying Maximum Working Space.

In the present paper, a space-arrangement system of structural element for multiple degree-of freedom parallel mechanisms with consideration of mutual interferences among structural elements such as links and pairs is investigated. In order to determine optimum profiles of links which satisfy the maximum working space of the end effector, a rotary plane which is arbitrary fixed on one of the moving link in the mechansim is introduced, and rdative loci of intersection points of the other moving links with the plane are analyzed. Moreover, conditions to determine link arrangements avoiding mutual interferences of moving links are formulated. Applying the above-mentioned system, a spatial six-DOF parallel mechanism with consideration of interferences among moving links is synthesized as a practical example.

Kinematic Analysis and Design of a 3 DOF Parallel Mechanism for a Passive Compliant Wrist of Manipulators.

A compliant wrist which combines passive compliance and active sensing is proposed to provide the necessary flexibility for force and contact control. This paper describes a mechanical design and a sensing technique of the compliant wrist. The compliant wrist has a three degrees of freedom parallel mechanism which has consists of two platforms connected by three serial chains. The kinematic equations for use of the wrist are derived, and the simulations are performed to estimate the performance of the proposed compliant wrist. It is shown that using the design method we can construct a compliant wrist which has a desired Cartesian stiffness and a suitable motion space.

Position analysis of a 3-DOF parallel manipulator

The forward and inverse kinematics of a 3-DOF parallel mechanism for beam aiming applications is derived in closed form. The mechanism has three actuated arms attached to a base via revolute joints. Another three arms are also attached to an upper platform via passive revolute joints. Each of the three base arms is connected to its respective opposing passive arm via a spherical joint. The platform has three degrees of freedom with respect to the base, two rotational and one radial motion.

Development and Experimentation of a Fast 3-DOF Camera-Orienting Device

In this article, the mechanical design and the practical im plementation of a high-performance, three-degree-of-freedom, camera-orienting device is addressed. The agile eye, as it is referred to, is based on a spherical 3-DOF parallel mechanism, which leads to high-performance dynamics. The kinematics of such a mechanism is briefly recalled, and its mechanical prop erties are described. Then, experimental results obtained with the prototype are presented and commented upon. Because of its low-moving inertia and its inherent stiffness, the mechanism is capable of velocities larger than 1,000°ls and of accelera tions larger than 20,000°/s2 .

二本指マイクロハンドの設計と微細作業

A prototype two-fingered micro hand is designed and is applied to the actual micro tasks. First, we discuss a concept of a two-fingered micro hand based on human usage of a pair of chopsticks. The two-fingered micro hand should be designed by considering the effective work space, or the common work space of two fingers, as well as the simplicity of its cooperation control for each finger. Our proposed prototype has two 6 DOF parallel mechanisms in series in order to realize similar motion in our chopsticks usage. We applied the prototype to practical micro manipulation tasks, and we succeeded in picking up a glass ball having size of 2 [μm] and placing it in arbitrary position under a microscope by human teleoperation.