On the Design of a 3-PRRR Spatial Parallel Compliant Mechanism

Author(s):  
Yang Wang ◽  
Cle´ment M. Gosselin

Because wear, clearance and backlash can be reduced or eliminated, one of the important advantages of compliant mechanisms is their potential to increase the mechanism precision dramatically. In this paper, a spatial compliant mechanism based on the 3-PRRR parallel mechanism driven by linear motors is presented. The design methodology is described and the kinematic and static models are developed. Using the “transmission ratio”, an effective and simple compensation method is designed. The performances of this mechanism are studied with the help of the structure simulation module in Pro-Mechanica. Using an open-loop control with compensation, measurements over a 20×20×20 mm3 workspace show that the position accuracy is smaller than 1 μm, i.e., 0.05% of the full range of motion and that the orientation error is less than 1 μradian.

Author(s):  
Matheus Garcia Soares ◽  
Afonso Bernardino Almeida Junior ◽  
Thiago Berger Canuto Alves ◽  
Luciano Martins Neto

AbstractThis work presents the improvement of an open loop control strategy for linear induction motors operating at low speeds. The improvement is provided through the application of genetic algorithms in determining unbalance factors of the supply voltages of the linear motor. For this, a computational model of the linear motor was used as the evaluation function. The computational model was developed based on the equations of the linearized induction motor. The proposed methodology is validated through the comparison between computational results and experimental data performed in a linear motor prototype. This methodology allows to evaluate the influence of the unbalance of the supply voltages for linear motors working at low speeds.


Author(s):  
Johannes Riemenschneider ◽  
Srinivas Vasista ◽  
Bram van de Kamp ◽  
Hans Peter Monner

Morphing is a technology with high potential to reduce emissions in aviation, since it enables wings to adapt their shape to operate at a higher efficiency over the full range of flight conditions. This paper is presenting a concept to adapt camber by drooping the nose. The scope is the setup and bench top testing of a full scale wing tip leading edge wind tunnel model with a morphing droop nose. The complete model features a span of 1.3 m and a strong taper from the root to the tip. For completeness, the design approach is covered as well. The design comprises a GFRP skin to be drooped by two compliant mechanisms, which are driven by linear motors. The compliant morphing devices are “designed-through-optimization”, with the optimization algorithms including Simplex optimization for composite compliant skin design, continuum-based and load path representation topology optimization methods for compliant internal substructure design. The compliant mechanism is manufactured by nickel-titanium alloy to allow high strains in the order of several percent, which is shown to be critical in the design of such compliant mechanisms. In order to validate the models, strains within the mechanisms are measured while drooping the nose in the bench top test. This is done after installing the mechanisms into the leading edge skin. It can be shown, that the simulation for the inboard mechanism is close to the experimental results. The comparison of strain levels in the skin and in the mechanism during droop reveals that the stiffness distribution between these two components is quite different. As a result this ratio can be taken into account in future design processes in order to distribute strains more evenly. Moreover the 3D shapes of the morphed and clean skin are measured and their comparison with the target shapes is presented as well. Finally, the bench top tests are a proof of concept for the overall concept and design which resultes in a “go” for the following low speed subsonic wind tunnel tests.


1998 ◽  
Author(s):  
C. Truman ◽  
Lenore McMackin ◽  
Robert Pierson ◽  
Kenneth Bishop ◽  
Ellen Chen

2008 ◽  
Author(s):  
Thomas Bifano ◽  
Jason Stewart ◽  
Alioune Diouf

Author(s):  
Girish Krishnan ◽  
Charles Kim ◽  
Sridhar Kota

Visualizing load flow aids in conceptual design synthesis of machine components. In this paper, we present a mathematical framework to visualize load flow in compliant mechanisms and structures. This framework uses the concept of transferred forces to quantify load flow from input to the output of a compliant mechanism. The key contribution of this paper is the identification a fundamental building block known as the Load-Transmitter Constraint (LTC) set, which enables load flow in a particular direction. The transferred force in each LTC set is shown to be independent of successive LTC sets that are attached to it. This enables a continuous visualization of load flow from the input to the output. Furthermore, we mathematically relate the load flow with the deformation behavior of the mechanism. We can thus explain the deformation behavior of a number of compliant mechanisms from literature by identifying its LTC sets to visualize load flow. This method can also be used to visualize load flow in optimal stiff structure topologies. The insight obtained from this visualization tool facilitates a systematic building block based design methodology for compliant mechanisms and structural topologies.


2011 ◽  
Vol 418-420 ◽  
pp. 1865-1868
Author(s):  
Ming Jin Yang ◽  
Xi Wen Li ◽  
Zhi Gang Wang ◽  
Tie Lin Shi

The performance of speed regulating is very important to the mixing process with safe, efficient operation and high quality of production. Strategies and practices of responses and optimization of a PID-based speed regulating system of a planetary mixer were presented in this paper. Research results show that: by means of the signal constraint function presented by Simulink Response Optimization, optimization PID parameters of the 2-DOF-PID controller can be obtained, and the response of close-loop control system has quite good performance of overshoot, response time, and stability compared with an open-loop control system.


2002 ◽  
Vol 21 (10-11) ◽  
pp. 849-859 ◽  
Author(s):  
Kenneth A. Mcisaac ◽  
James P. Ostrowski

In this paper, we describe experimental work using an underwater, biomimetic, eel-like robot to verify a simplified dynamic model and open-loop control routines. We compare experimental results to previous analytically derived, but approximate expressions for proposed gaits for forward/backward swimming, circular swimming, sideways swimming and turning in place. We have developed a five-link, underwater eel-like robot, focusing on modularity, reliability and rapid prototyping, to verify our theoretical predictions. Results from open-loop experiments performed with this robot in an aquatic environment using an off-line vision system for position sensing show good agreement with theory.


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