Analysis of Planar Reconfigurable Motion Generators

This article presents the kinematic analysis of a new class of mechanical devices called planar Reconfigurable Motion Generators (RMGs) for multi-phase motion generation tasks having only a slight change in the desired motion. The concepts of configuration matrices and state vectors are introduced as a novel way to represent planar RMGs. The kinematic analysis of a planar RMG in it’s initial configuration to determine the associated adjustable link lengths and angles is discussed. The adjustable link lengths are used to determine the link vector and state vector of a RMG. Future work will involve the application of configuration matrices and state vectors to aid in both systematic analysis and synthesis of RMGs. INTRODUCTION This paper presents the kinematic analysis of a new class of machines called Reconfigurable Motion Generators (RMGs) for multi-phase planar motion generation. RMGs are a new class of mechanical devices designed around a specific part family of products having only a slight variation and allow changes in their structure for motion planning tasks, Larochelle and Venkataramanujam [1]. Traditional hard automation linkage or cam driven mechanisms provide an extremely high speed capability at a relatively low cost. This is desirable for automation tasks that are not expected to change (i.e., hard). However in automation tasks where ∗Address all correspondence to this author. there is a requirement for flexibility in the motion generation tasks (i.e., soft), these machines are inadequate and call for the implementation of multi d.o.f. serial chain manipulators. Multi d.o.f. serial chain manipulators offer more flexibility and have the ability to adapt to a variety of divergent tasks. However, they are expensive to procure and maintain and have relatively longer cycle times. In most industrial situations the requirements for flexibility in operations are very limited. A typical serial chain robot may be only used for a few distinct pick-and-place operations throughout its operational life. This results in inadequate utilization of the robot. A discussion on the relative advantages and disadvantages of closed chain mechanisms and serial chain manipulators may be found in, Kota [2] and Larochelle and Venkataramanujam [1]. There is a need for a new class of mechanical devices that offer the speed of hard automation mechanisms along with some degree of the operational flexibility found in serial chain manipulators. Reconfigurable Motion Generators are a new class of mechanical devices conceived to address this need. An arrangement of brakes at the passive R joints for link adjustment in a five-bar two d.o.f. mechanism in order to enable multi-phase motion generation has been proposed by Larochelle and Venkataramanujam [1]. It has been shown that for a fivebar mechanism with brakes instead of passive revolute joints we can obtain four distinct four-bar mechanisms or configurations. Formulations involving link geometry and joint configuration are developed to yield the adjustable link lengths and their associated joint parameters for a certain configuration. The analyses preProceedings of the ASME 2014 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2014 August 17-20, 2014, Buffalo, New York, USA