Using Singularities of Parallel Manipulators for Enhancing the Rigid-body Replacement Design Method of Compliant Mechanisms

International audienceThe rigid-body replacement method is often used when designing a compliant mechanism. The stiffness of the compliant mechanism, one of its main properties, is then highly dependent on the initial choice of a rigid-body architecture. In this paper, we propose to enhance the efficiency of the synthesis method by focusing on the architecture selection. This selection is done by considering the required mobilities and parallel manipulators in singularity to achieve them. Kinematic singularities of parallel structures are indeed advantageously used to propose compliant mechanisms with interesting stiffness properties. The approach is first illustrated by an example, the design of a one degree of freedom compliant architecture. Then the method is used to design a medical device where a compliant mechanism with three degrees of freedom is needed. The interest of the approach is outlined after application of the method

Design of a compensation mechanism for an active cardiac stabilizer based on an assembly of planar compliant mechanisms

Surgical robotics helps to increase the surgeon’s accuracy and limits the invasiveness of the surgery. The complexity of an operation room implies to design surgical devices that are as compact as possible and that can be easily sterilized. One interesting design approach is to combine compliant mechanisms, which have a monolithic structure, and piezoelectric actuators. Based on this approach, a robotic device for minimally invasive coronary artery bypass grafting has been proposed previously in our laboratory. It is composed of a shaft with two fingers in contact with the heart at one end, and an actuated compensation mechanism at the other end. This device successfully helps to increase the stabilization of the heart surface during the surgery but its needs to be increased for an optimal integration in the operation room. One possibility is to reduce the size of the compensation by considering an assembly of planar manufactured structures. This helps to simplify the manufacturing process and may increase the compactness. Parallel architectures constitute interesting solutions for their intrinsic stiffness properties, but in a planar configuration parallel manipulators often exhibit kinematic singularities. Two design approaches for planar parallel compliant mechanisms are presented in this paper. One design approach consists in designing a passive compliant mechanism in a configuration close to the singularity by introducing some asymmetries during the manufacturing process. The second design approach consists in taking advantage of the singularities of parallel manipulators. In fact, in some singular configurations, the end-effector of the manipulator loses stiffness while its actuators are blocked. As compliant mechanisms only work around a given configuration this loss of stiffness is used to produce the required mobilities. The final device, composed of planar compliant mechanisms, is finally presented. Finite element analysis simulations of the whole device during the compensation task give encouraging results

Industrial Robotics

This book covers a wide range of topics relating to advanced industrial robotics, sensors and automation technologies. Although being highly technical and complex in nature, the papers presented in this book represent some of the latest cutting edge technologies and advancements in industrial robotics technology. This book covers topics such as networking, properties of manipulators, forward and inverse robot arm kinematics, motion path-planning, machine vision and many other practical topics too numerous to list here. The authors and editor of this book wish to inspire people, especially young ones, to get involved with robotic and mechatronic engineering technology and to develop new and exciting practical applications, perhaps using the ideas and concepts presented herein