Safe joint mechanism using inclined link with springs for collision safety and positioning accuracy of a robot arm

2010 ◽  
Author(s):  
Jung-Jun Park ◽  
Jae-Bok Song
Keyword(s):  
Robot Arm ◽  
Positioning Accuracy ◽  
Collision Safety ◽  
Joint Mechanism

scholarly journals Safe Joint Mechanism using torsion springs for Collision Safety and Positioning Accuracy of a Robot Arm

2020 ◽  
Author(s):  
Adel Belharet ◽  
Jae-Bok Song
Keyword(s):  
Service Robots ◽  
Robot Arm ◽  
Positioning Accuracy ◽  
External Torque ◽  
High Stiffness ◽  
Collision Safety ◽  
Passive Compliance ◽  
Joint Mechanism ◽  
Mechanical Elements ◽  
Torsion Springs

In recent years, the potential for collision between humans and robots has drawn much attention since service robots are increasingly being used in the human environment. A safe robot arm can be achieved using either an active or passive compliance method. A passive compliance system composed of purely mechanical elements often provides faster and more reliable responses to dynamic collision than an active system involving sensors and actuators. Since positioning accuracy and collision safety of a robot arm are equally important, a robot arm should have very low stiffness when subjected to a collision force capable of causing human injury. Otherwise, it should maintain a very high stiffness. To implement these requirements, a novel safe joint mechanism (SJM-IV) consisting of a CAM, rotational links with rollers, and torsion springs is proposed. The SJM-IV has the advantage of nonlinear stiffness, which can be achieved only with passive mechanical elements. Various analyses and experiments on static and dynamic collisions show high stiffness of the SJM-IV against an external torque less than a predetermined threshold torque, with an abrupt drop in stiffness when the external torque exceeds this threshold. The safe joint mechanism enables a robot manipulator to guarantee positioning accuracy and collision safety, and which is simple to install between an actuator and a robot link without a significant change in the robot’s design.

A Nonlinear Stiffness Safe Joint Mechanism Design for Human Robot Interaction

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Jung-Jun Park ◽  
Jae-Bok Song
Keyword(s):  
Human Robot Interaction ◽  
Service Robots ◽  
Robot Arm ◽  
Positioning Accuracy ◽  
External Torque ◽  
High Stiffness ◽  
Collision Safety ◽  
Passive Compliance ◽  
Joint Mechanism ◽  
Mechanical Elements

Service robots used in human environments must be designed to avoid collisions with humans. A safe robot arm can be designed using active or passive compliance methods. A passive compliance system composed of purely mechanical elements often provides faster and more reliable responses for dynamic collision than an active one involving sensors and actuators. Because positioning accuracy and collision safety are equally important, a robot arm should have very low stiffness when subjected to a collision force that could cause human injury but should otherwise maintain very high stiffness. A novel safe joint mechanism (SJM) consisting of linear springs and a double-slider mechanism is proposed to address these requirements. The SJM has variable stiffness that can be achieved with only passive mechanical elements. Analyses and experiments on static and dynamic collisions show high stiffness against an external torque less than a predetermined threshold value and an abrupt drop in stiffness when the external torque exceeds this threshold. The SJM enables the robotic manipulator to guarantee positioning accuracy and collision safety and it is simple to install between an actuator and a robot link without a significant change in the robot’s design.

scholarly journals Calibration of Kinematic Parameters of Robot Arm Using Laser Tracking System: Compensation for Non-Geometric Errors by Neural Networks and Selection of Optimal Measuring Points by Genetic Algorithm

2012 ◽  
Vol 6 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Seiji Aoyagi ◽  
◽  
Masato Suzuki ◽  
Tomokazu Takahashi ◽  
Jun Fujioka ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Neural Networks ◽  
Tracking System ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Geometric Parameters ◽  
Geometric Errors ◽  
Robot Arm ◽  
Positioning Accuracy ◽  
Laser Tracking

Offline teaching based on high positioning accuracy of a robot arm is desired to take the place of manual teaching. In offline teaching, joint angles are calculated using a kinematic model of the robot arm. However, a nominal kinematic model does not consider the errors arising in manufacturing or assembly, not to mention the non-geometric errors arising in gear transmission, arm compliance, etc. Therefore, a method of precisely calibrating the parameters in a kinematic model is required. For this purpose, it is necessary to measure the three-dimensional (3-D) absolute position of the tip of a robot arm. In this paper, a laser tracking system is employed as the measurement apparatus. The geometric parameters in the robot kinematic model are calibrated by minimizing errors between the measured positions and the predicted ones based on the model. The residual errors caused by non-geometric parameters are further reduced by using neural networks, realizing high positioning accuracy of sub-millimeter order. To speed up the calibration process, a smaller number of measuring points is preferable. Optimal measuring points, which realize high positioning accuracy while remaining small in number, are selected using Genetic Algorithm (GA).

The Performance Analysis of Humanoid Massage Robot Arm Based on SolidWorks

2013 ◽  
Vol 753-755 ◽  
pp. 1011-1015
Author(s):  
Zai Xiang Pang ◽  
Lin An Gong ◽  
Da Wei Jiang ◽  
Tie Jun Liu
Keyword(s):  
Optimization Design ◽  
Parametric Model ◽  
Robot Arm ◽  
Analysis Software ◽  
Element Analysis ◽  
Positioning Accuracy ◽  
Design Requirements ◽  
Main Factors ◽  
Stiffness Characteristics ◽  
Strength And Stiffness

The strength and stiffness of humanoid massage robot arm are the main factors that they affect the dynamic characteristics and positioning accuracy under the action of the load. In order to analysis the strength and stiffness characteristics of humanoid massage robot arm. With SolidWorks we establish parametric model and by finite element analysis software ANSYS analyses the strength and stiffness of key parts and components. Emulational results show that the stiffness and strength of humanoid massage robot arm that we design and invent meet the design requirements, lay a foundation for further optimization design.

scholarly journals DEVELOPMENT OF A NEW ROBOT ARM JOINT MECHANISM BASED ON HUMAN SHOULDER MECHANISM

Biomechanisms ◽  
2004 ◽  
Vol 17 ◽  
pp. 143-155
Author(s):  
Nobuo SAKAI ◽  
Teruo MURAKAMI ◽  
Yoshinori SAWAE
Keyword(s):  
Robot Arm ◽  
Joint Mechanism

Positioning Accuracy of Robot Arm by Synchronous Belt Drives : Investigation by FEM Analysis

2004 ◽  
Vol 2004 (0) ◽  
pp. 237-240
Author(s):  
Shinji KIKUNO ◽  
Masanori KAGOTANI ◽  
Naoya KITAMOTO ◽  
Hiroyuki UEDA ◽  
Tomio KOYAMA
Keyword(s):  
Fem Analysis ◽  
Robot Arm ◽  
Positioning Accuracy ◽  
Belt Drives
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