Showing papers on "Compliant mechanism published in 1999"
TL;DR: In this article, an improved objective formulation based on maximizing the energy throughput of a linear static compliant mechanism is developed considering specific force and displacement operational requirements, which allows stress constraints to limit the maximum stress in the mechanism.
Abstract: Compliant mechanisms are jointless mechanical devices that take advantage of elastic deformation to achieve a force or motion transformation. An important step toward automated design of compliant mechanisms has been the development of topology optimization techniques. The next logical step is to incorporate size and shape optimization to perform dimensional synthesis of the mechanism while simultaneously considering practical design specifications such as kinematic and stress constraints. An improved objective formulation based on maximizing the energy throughput of a linear static compliant mechanism is developed considering specific force and displacement operational requirements. Parametric finite element beam models are used to perform the size and shape optimization. This technique allows stress constraints to limit the maximum stress in the mechanism. In addition, constraints which restrict the kinematics of the mechanism are successfully applied to the optimization problem. Resulting optimized mechanisms exhibit efficient mechanical transmission and meet kinematic and stress requirements. Several examples are given to demonstrate the effectiveness of the optimization procedure.
156 citations
TL;DR: In this article, a novel approach to static shape control of smart structures is introduced, which uses a special class of mechanisms called compliant mechanisms powered by a single input actuator, and the key design issue in this approach is the synthesis of a suitable compliant mechanism for the task.
Abstract: A novel approach to static shape control of smart structures is introduced. This approach uses a special class of mechanisms called compliant mechanisms powered by a single input actuator. The key design Issue in this approach is the synthesis of a suitable compliant mechanism for the task. A systematic procedure for synthesis of such compliant mechanisms is presented by combining the first principles of mechanics and kinematics through a structural optimization scheme. The procedure is illustrated by an example wherein a prescribed smooth shape change in the camber of an idealized airfoil structure is accomplished by a specially synthesized compliant mechanism actuated by a single torque input. The scope and benefits of the proposed approach in providing viable simple solutions for real-scale static shape control applications are also discussed.
134 citations
TL;DR: In this article, the authors present a generalized methodology for designing compliant mechanisms for topology generation and size and shape optimization, and demonstrate integration with electrostatic, piezoelectric, and SMA actuators for MEMS and smart-structures applications.
Abstract: Matching a drive system to the force-displacement characteristics of the load is the cardinal principle in electromechanical systems design. Unconventional actuation schemes; such as piezoelectric, electrostatic, and shape-memory alloys (SMAs), seem to exhibit certain limitations in terms of power density, stroke length, bandwidth, etc., when one attempts to employ them directly to an application. Integrating them with mechanical transmission elements so that the integrated actuator-transmission system matches the load characteristics of the application can enhance the utility of such unconventional actuators. Conventional mechanical devices are sometimes difficult to integrate with unconventional actuating schemes. For instance, the two-dimensional nature of microelectromechanical systems (MEMS) and no-assembly constraints arising from their batch fabrication make it difficult to fabricate, assemble, and integrate a conventional micromechanism with an electrostatic actuator. However, a monolithic "solid-state" mechanical transmission device enables easy integration. The paper presents a systematic method of designing such unconventional mechanisms. The paper presents a generalized methodology for designing compliant mechanisms. Our systematic synthesis formulations provide a mathematical basis for designing compliant mechanisms for: (1) topology generation and (2) size and shape optimization. Design examples illustrate integration with electrostatic, piezoelectric, and SMA actuators for MEMS and smart-structures applications.
128 citations
TL;DR: Data is presented that characterizes the microgripper performance under both pure position and pure force control, followed by a discussion of the attributes and limitations of flexure-based design.
Abstract: A small-scale flexure-based gripper was designed for manipulation tasks requiring precision position and force control. The gripper is actuated by a piezoelectric ceramic stack actuator and utilizes strain gages to measure both the gripping force and displacement. The position and force bandwidths were designed for ten Hertz and one hundred Hertz, respectively, in order to afford human-based teleoperative transparency. The gripper serves effectively as a one degree-of-freedom investigation of compliant mechanism design for position and force controlled micromanipulation. Data is presented that characterizes the microgripper performance under both pure position and pure force control, followed by a discussion of the attributes and limitations of flexure-based design.
117 citations
TL;DR: In this article, a procedure for the topology design of compliant mechanisms with multiple output requirements is presented, and a combined virtual load method and a weighted sum of objectives method are developed.
Abstract: A procedure for the topology design of compliant mechanisms with multiple output requirements is presented. Two methods for handling the multiple output requirements are developed, a combined virtual load method and a weighted sum of objectives method. The problem formulations and numerical solution procedures are discussed and illustrated by design examples. The examples illustrate the capabilities of the design procedure, the effect of the direction of the output deflection requirements on the solution, as well as computational issues such as the effect of the starting point and effect of the material resource constraint.
100 citations
TL;DR: The split-tube flexure as mentioned in this paper is a unique flexure joint that incorporates torsion as the primary mode of deformation, and contrasts the torsional properties of a thin-walled open-section member with the bending properties of that member to obtain desirable joint behavior.
Abstract: This paper describes the design of a unique revolute flexure joint, called a split-tube flexure, that enables (lumped compliance) compliant mechanism design with a considerably larger range-of-motion than a conventional thin beam flexure, and additionally provides significantly better multi-axis revolute joint characteristics. Conventional flexure joints utilize bending as the primary mechanism of deformation. In contrast, the split-tube flexure joint incorporates torsion as the primary mode of deformation, and contrasts the torsional properties of a thin-walled open-section member with the bending properties of that member to obtain desirable joint behavior. The development of this joint enables the development of compliant mechanisms that are quite compliant along kinematic axes, extremely stiff along structural axes, and are capable of kinematically well-behaved large motions.
98 citations
Patent•
15 Dec 1999
TL;DR: In this article, a mechanism capable of achieving an arbitrarily specified spatial compliant behavior is presented, which is a parallel connection of multiple individual elastic components that connect a support body to a single compliantly floated body, each elastic component is, in itself, a low friction 6 degrees of freedom (DOF) mechanism that provides compliant constraint along and/or about a single axis.
Abstract: A mechanism capable of achieving an arbitrarily specified spatial compliant behavior is presented. The mechanism is a parallel connection of multiple individual elastic components that connect a support body to a single compliantly floated body. Each elastic component is, in itself, a low friction 6 degrees of freedom (DOF) mechanism that provides compliant constraint along and/or about a single axis. The elastic components are of three functional types: 1) a “line spring” which resists only translation along its axis, 2) a “torsional spring” which resists only rotation about its axis, and 3) a “screw spring” which resists a specified combination of translation along and rotation about its axis. Through proper selection of the connection geometry, spring constant, and functional type of each elastic component, a spatial compliant mechanism capable of passive force guidance is realized.
66 citations
Patent•
15 Jan 1999
TL;DR: In this paper, compliant mechanisms are arranged to enable airfoil and other structures to adapt their shapes to different flight conditions and thereby achieve optimum lift: drag ratios in plural flight conditions.
Abstract: Compliant mechanisms are arranged to enable airfoil and other structures to adapt their shapes to different flight conditions and thereby achieve optimum lift: drag ratios in plural flight conditions. The compliant mechanisms can be formed integrally whereby a compliant frame thereof, or the skin of the airfoil, undergo elastic or other deformation to produce the desired displacements in direct response to applied forces. In an airfoil context, shape changes can be effected by the leading and trailing edges of the entire airfoil system. In addition, the driver arrangements of the compliant mechanisms can be controlled individually to effect a desired surface contour throughout the length of the wing, illustratively a twist therein.
56 citations
TL;DR: In this paper, the authors used the pseudo-rigid-body model to predict the first modal response of compliant mechanisms, and the model predictions were within 9 percent of the experimental results for all cases.
Abstract: The pseudo-rigid-body modeling technique is used to simplify the nonlinear analysis of compliant mechanisms. This paper presents the first work that investigates the possibility of using the pseudo-rigid-body model to predict the first modal response of compliant mechanisms. Four different configurations of the parallel-guiding mechanism are modeled and tested, as well as two configurations of compliant straight-line mechanisms. The model predictions of the first natural frequencies were compared with experimental results for all six mechanism configurations. The model predictions are within 9 percent of the experimental results for all cases.
52 citations
12 Sep 1999
TL;DR: The use of topology optimization as a synthesis tool for the design of large-displacement compliant mechanisms is described and the optimization problem is solved using the method of moving asymptotes.
Abstract: This paper describes the use of topology optimization as a synthesis tool for the design of large-displacement compliant mechanisms. An objective function for the synthesis of large-displacement mechanisms is proposed together with a formulation for synthesis of path-generating compliant mechanisms. The responses of the compliant mechanisms are modelled using a total Lagrangian finite element formulation, the sensitivity analysis is performed using the adjoint method and the optimization problem is solved using the method of moving asymptotes. Procedures to circumvent some numerical problems are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
40 citations
20 Jul 1999
TL;DR: In this article, the authors present an overview of mathematical procedures employed for designing compliant mechanisms, including topological synthesis, size and shape optimization to meet performance requirements, and some examples of compliant MEMS are presented.
Abstract: Compliant mechanisms are monolithic mechanical structures that rely on elastic deformation to generate sophisticated mechanical functions. This paper presents an overview of mathematical procedures employed for designing compliant mechanisms. The paper outlines: (1) topological synthesis-- which involves generation of a functional design in the form of a feasible topology starting from input/output force/motion specifications, and (2) size and shape optimization--to meet performance requirements. Some examples of compliant MEMS are also presented.
09 Jun 1999
TL;DR: In this article, a compliant gripper that is 7-mm by 17-mm, made from a single piece of titanium that is designed to function as a needle driver for small scale suturing is presented.
Abstract: Recent advances in robotics, tele-robotics, smart material actuators, and mechatronics raise new possibilities for innovative developments in millimeter-scale robotics capable of manipulating objects only fractions of a millimeter in size. These advances can have a wide range of applications in the biomedical community. A potential application of this technology is in minimally invasive surgery (MIS). The focus of this paper is the development of a single degree of freedom prototype to demonstrate the viability of smart materials, force feedback and compliant mechanisms for minimally invasive surgery. The prototype is a compliant gripper that is 7-mm by 17-mm, made from a single piece of titanium that is designed to function as a needle driver for small scale suturing. A custom designed piezoelectric `inchworm' actuator drives the gripper. The integrated system is computer controlled providing a user interface device capable of force feedback. The design methodology described draws from recent advances in three emerging fields in engineering: design of innovative tools for MIS, design of compliant mechanisms, and design of smart materials and actuators. The focus of this paper is on the design of a millimeter-scale inchworm actuator for use with a compliant end effector in MIS.
10 May 1999
TL;DR: This paper addresses the modeling and control of a compliant micromanipulator for use in such fields as microsurgery, telesurgery, and microassembly with a unique flexure-based manipulator that utilizes revolute flexure joints in achieving well-behaved kinematic characteristics without the backlash and stick-slip phenomena.
Abstract: This paper addresses the modeling and control of a compliant micromanipulator for use in such fields as microsurgery, telesurgery, and microassembly. The unique flexure-based manipulator utilizes revolute flexure joints in achieving well-behaved kinematic characteristics, without the backlash and stick-slip phenomena that would otherwise impede precision control. A mathematical model of the micromanipulator is formulated, and a controller for positioning of the manipulator is derived. The model and resulting controller are unlike typical manipulator models and controllers since this manipulator is actually a controlled large range-of-motion structure with nonlinear structural dynamics. Following the development of the controller, computer simulations of the proposed controller on the manipulator are used to verify the positioning performance.
01 Jan 1999
TL;DR: In this paper, the authors present a compliant mechanism for transferring live objects from a moving conveyor to a moving processing line. But their model is restricted to the case where the object is typically characterized by varying sizes and shapes and their natural reflexes contribute to the overall dynamics.
Abstract: This paper presents the design, modeling and analysis of a novel compliant mechanism for automating the process of transferring live objects from a moving conveyor to a moving processing line. Unlike industrial man-made objects, natural objects are typically characterized by varying sizes and shapes in batch processing and their natural reflexes (or voluntarily motion) contribute to the overall dynamics. The dynamic model of the manipulating system consists of two parts: the forces acting on the object and the natural reflexes of the live object to the manipulation. In this paper an analytical model is presented to predict the forces/moments acting on the live objects.
12 Sep 1999
TL;DR: In this article, a pseudo-rigid-body model for initially circular functionally binary pinned-pinned segments is presented, which approximates the functionally binary segment as three rigid members joined by pin joints, and torsional springs placed at the joints model the segment's stiffness.
Abstract: The pseudo-rigid-body model concept allows compliant mechanisms to be analyzed using well-known rigid-body kinematics. This paper presents a pseudo-rigid-body model for initially circular functionally binary pinned-pinned segments that undergo large, nonlinear deflections. The model approximates the functionally binary pinned-pinned segment as three rigid members joined by pin joints. Torsional springs placed at the joints model the segment’s stiffness. This model has been tested by fabricating several such segments from a variety of different materials. An example mechanism incorporating functionally binary pinned-pinned segments is also presented.
Dissertation•
01 Jan 1999
04 Jun 1999
TL;DR: In this article, a cantilever beam model is used to examine the solution behavior of various objective functions intended for compliant mechanism optimization, and a new objective function based on maximizing the energy throughput of a compliant mechanism pushing against an external spring is presented.
Abstract: Compliant mechanisms are devices which utilize elastic deformation to emulate the behavior of conventional rigid mechanisms. Structural optimization techniques represent a relatively new approach for automating topology synthesis of compliant mechanisms. A cantilever beam model is presented in order to examine the solution behavior of various objective functions intended for compliant mechanism optimization. The model reveals that objective functions which attempt to simultaneously maximize the flexibility and stiffness of a compliant mechanism can be formulated such that they are not well-bounded. Topology optimization problems using these types of objective functions may exhibit heightened convergence sensitivity with respect to the lower design variable bound. The cantilever beam model is also used to develop a new objective function based on maximizing the energy throughput of a compliant mechanism pushing against an external spring. The objective function shows a well-bounded solution to the simple beam model and consequently exhibits more robust optimization convergence. A simple numerical example is given which demonstrates the heightened robustness of the formulation.
TL;DR: In this paper, a simple strategy for carrying a large object with the cooperation of multiple position-controlled robots is proposed, and the maximum number of robots that can directly support a single object is determined.
Abstract: A simple strategy for carrying a large object with the cooperation of multiple position-controlled robots is proposed. In cooperative systems handling single objects, compliance is necessary for each robot to avoid excessive inner forces caused by mutual positioning errors. However, since the majority of commercial industrial robots have PID position controllers, the necessary compliance cannot be achieved by servo systems. Thus, mechanisms consisting of passive joints are installed in a cooperative System as mechanical compliance. First, the mechanical compliance required for the cooperation of position-controlled robots is derived. From the theoretical results, it is determined that the maximum number of robots that can directly support a single object is six. Second, the statics and error characteristics of cooperative systems including compliant mechanisms are analyzed. An example of the cooperation of three mobile robots is designed using passive joint mechanisms. Finally, the strategy is extended to cooperation among an arbitrary number of mobile robots by building hierarchical structures with passive joints.
15 Dec 1999-Jsme International Journal Series C-mechanical Systems Machine Elements and Manufacturing
TL;DR: In this paper, the authors presented a methodology to obtain an optimal structural configuration of a flextensional actuator using the homogenization design method, where the extended kinematic flexibility defined as the mean transduction was formulated using a mutual energy concept.
Abstract: A flexible mechanical structure can provide an additional function, such as a kinematic function if flexibility is implemented in some appropriate portions. This flexible structure can be used as a new type of mechanisms which are called compliant mechanisms. We can also construct so-called flextensional actuators by combining the flexible structure with piezoceramic material. In this study, we present a methodology to obtain an optimal structural configuration of a flextensional actuator using the homogenization design method. First, the extended kinematic flexibility defined as the mean transduction is formulated using a mutual energy concept. Second, we propose a new multi-objective function incorporating the kinematic flexibility and stiffness. Next, an optimization procedure is constructed based on the homogenization method and sequential linear programming(SLP). Finally, some examples are presented to confirm the problem specifications of the optimal configurations.
12 Sep 1999
TL;DR: In this paper, the authors extend the homogenization design method for topology/shape optimization for elastic structures into the design of flexible structures such as compliant mechanisms, which is a relatively new breed of jointless mechanism in which elastic deformation is intended to be a source of motion.
Abstract: Structural optimization using the homogenization method which was introduced by Bendsφe and Kikuchi in 1988 is established as a theory of optimal design of layout (topology and shape). This theory has been applied to the various kind of problems, especially in meso-micro-scale desing, for example in the microstructure of composite and piezo-ceramic material. Frecker and Nishiwaki studied the possibility of the extension of the homogenization design method for topology/shape optimization for elastic structures into the design of flexible structures such as compliant mechanisms. Compliant mechanisms is a relatively new breed of jointless mechanism in which elastic deformation is intended to be a source of motion. In the past, most flexible structural design optimization was considered only for the direction of the flexible point, by using the material density or equivalent homogenization method to identify the optimum layout. Here we shall extend it to the case of a two dimensional design for compliant mechanism which control the deflection of the flexible point. Moreover we also applied the image based design method to extract a FE model for prototype from the optimal layout and propose the integrated structural design methodology.