Preface. 1. Introduction. 2. Rigid Motions and Homogeneous Transformations. 3. Forward and Inverse Kinematics. 4. Velocity Kinematics-The Jacobian. 5. Path and Trajectory Planning. 6. Independent Joint Control. 7. Dynamics. 8. Multivariable Control. 9. Force Control. 10. Geometric Nonlinear Control. 11. Computer Vision. 12. Vision-Based Control. Appendix A: Trigonometry. Appendix B: Linear Algebra. Appendix C: Dynamical Systems. Appendix D: Lyapunov Stability. Index.

/pdf/robot-modeling-and-control-2n3memrp6g.pdf

Robot Modeling and Control

Electrical actuators were made from films of dielectric elastomers (such as silicones) coated on both sides with compliant electrode material. When voltage was applied, the resulting electrostatic forces compressed the film in thickness and expanded it in area, producing strains up to 30 to 40%. It is now shown that prestraining the film further improves the performance of these devices. Actuated strains up to 117% were demonstrated with silicone elastomers, and up to 215% with acrylic elastomers using biaxially and uniaxially prestrained films. The strain, pressure, and response time of silicone exceeded those of natural muscle; specific energy densities greatly exceeded those of other field-actuated materials. Because the actuation mechanism is faster than in other high-strain electroactive polymers, this technology may be suitable for diverse applications.

http://science.sciencemag.org/content/sci/287/5454/836.full.pdf

High-Speed Electrically Actuated Elastomers with Strain Greater Than 100%

The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.

Synthetic molecular motors and mechanical machines.

This tutorial/survey paper: (1) provides a concise point of departure for researchers and practitioners alike wishing to assess the current state of the art in the control and monitoring of civil engineering structures; and (2) provides a link between structural control and other fields of control theory, pointing out both differences and similarities, and points out where future research and application efforts are likely to prove fruitful. The paper consists of the following sections: section 1 is an introduction; section 2 deals with passive energy dissipation; section 3 deals with active control; section 4 deals with hybrid and semiactive control systems; section 5 discusses sensors for structural control; section 6 deals with smart material systems; section 7 deals with health monitoring and damage detection; and section 8 deals with research needs. An extensive list of references is provided in the references section.

Structural control: past, present, and future

The widespread use of molecular machines in biology has long suggested that great rewards could come from bridging the gap between synthetic molecular systems and the machines of the macroscopic world. In the last two decades, it has proved possible to design synthetic molecular systems with architectures where triggered large amplitude positional changes of submolecular components occur. Perhaps the best way to appreciate the technological potential of controlled molecular-level motion is to recognize that nanomotors and molecular-level machines lie at the heart of every significant biological process. Over billions of years of evolution, nature has not repeatedly chosen this solution for performing complex tasks without good reason. When mankind learns how to build artificial structures that can control and exploit molecular level motion and interface their effects directly with other molecular-level substructures and the outside world, it will potentially impact on every aspect of functional molecule and materials design. An improved understanding of physics and biology will surely follow.

The first steps on the long path to the invention of artificial molecular machines were arguably taken in 1827 when the Scottish botanist Robert Brown observed the haphazard motion of tiny particles under his microscope.1,2 The explanation for Brownian motion, that it is caused by bombardment of the particles by molecules as a consequence of the kinetic theory of matter, was later provided by Einstein, followed by experimental verification by Perrin.3,4 The random thermal motion of molecules and its implications for the laws of thermodynamics in turn inspired Gedankenexperiments (“thought experiments”) that explored the interplay (and apparent paradoxes) of Brownian motion and the Second Law of Thermodynamics. Richard Feynman’s famous 1959 lecture “There’s plenty of room at the bottom” outlined some of the promise that manmade molecular machines might hold.5,6 However, Feynman’s talk came at a time before chemists had the necessary synthetic and analytical tools to make molecular machines. While interest among synthetic chemists began to grow in the 1970s and 1980s, progress accelerated in the 1990s, particularly with the invention of methods to make mechanically interlocked molecular systems (catenanes and rotaxanes) and control and switch the relative positions of their components.7−24

Here, we review triggered large-amplitude motions in molecular structures and the changes in properties these can produce. We concentrate on conformational and configurational changes in wholly covalently bonded molecules and on catenanes and rotaxanes in which switching is brought about by various stimuli (light, electrochemistry, pH, heat, solvent polarity, cation or anion binding, allosteric effects, temperature, reversible covalent bond formation, etc.). Finally, we discuss the latest generations of sophisticated synthetic molecular machine systems in which the controlled motion of subcomponents is used to perform complex tasks, paving the way to applications and the realization of a new era of “molecular nanotechnology”.

1.1. The Language Used To Describe Molecular Machines
Terminology needs to be properly and appropriately defined and these meanings used consistently to effectively convey scientific concepts. Nowhere is the need for accurate scientific language more apparent than in the field of molecular machines. Much of the terminology used to describe molecular-level machines has its origins in observations made by biologists and physicists, and their findings and descriptions have often been misinterpreted and misunderstood by chemists. In 2007 we formalized definitions of some common terms used in the field (e.g., “machine”, “switch”, “motor”, “ratchet”, etc.) so that chemists could use them in a manner consistent with the meanings understood by biologists and physicists who study molecular-level machines.14

The word “machine” implies a mechanical movement that accomplishes a useful task. This Review concentrates on systems where a stimulus triggers the controlled, relatively large amplitude (or directional) motion of one molecular or submolecular component relative to another that can potentially result in a net task being performed. Molecular machines can be further categorized into various classes such as “motors” and “switches” whose behavior differs significantly.14 For example, in a rotaxane-based “switch”, the change in position of a macrocycle on the thread of the rotaxane influences the system only as a function of state. Returning the components of a molecular switch to their original position undoes any work done, and so a switch cannot be used repetitively and progressively to do work. A “motor”, on the other hand, influences a system as a function of trajectory, meaning that when the components of a molecular motor return to their original positions, for example, after a 360° directional rotation, any work that has been done is not undone unless the motor is subsequently rotated by 360° in the reverse direction. This difference in behavior is significant; no “switch-based” molecular machine can be used to progressively perform work in the way that biological motors can, such as those from the kinesin, myosin, and dynein superfamilies, unless the switch is part of a larger ratchet mechanism.14

Artificial Molecular Machines

Microscale grasping and manipulation has opened new avenues in the field of bio-manipulation and assembly of MEMS components Ionic polymer metal composite (IPMC) artificial muscles offer a promising approach for manipulating flexible objects like biological cells IPMC membranes are electroactive, and therefore bend when a voltage is applied across them Since they are both flexible and compliant, they do not damage fragile objects during manipulation IPMCs can be cut as small as desired without losing any of their properties, and are therefore ideal for micromanipulation applications This paper describes how these IPMCs in a microgripper configuration can be used to grasp flexible objects and presents experimental results of the first generation IPMC microgripper

http://ieeexplore.ieee.org/iel5/9827/30979/01438551.pdf

Grasping flexible objects using artificial muscle microgrippers

A new design for shape memory alloy rotatory joint actuators using shape memory effect and pseudoelastic effect is presented. In this design, one SMA wire works with its shape memory effect, while the other SMA wire works with its pseudoelastic effect. The pseudoelastic type of SMA wire provides the shape memory type of SMA wire with bias force, and therefore, the bias spring in a bias force type of SMA actuator can be eliminated. A quasi-static analysis of this type of actuators is performed which incorporates a varying load torque. General stress-strain relation and stress- temperature relation of the shape memory effect wire and a formula for an equivalent spring rate of the pseudoelastic wire are derived. Liang and Rogers' model for shape memory materials is used for the analysis. An experimental method to obtain the equivalent spring rate is also described. Design formulas for a simplified design are derived based on the quasi-static analysis of the actuator.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Design for shape memory alloy rotatory joint actuators using shape memory effect and pseudoelastic effect

A projectile for a railgun that uses a hybrid armature and provides a seed block around part of the outer surface of the projectile to seed the hybrid plasma brush. In addition, the hybrid armature is continuously vaporized to replenish plasma in a plasma armature to provide a tandem armature and provides a unique ridge and groove to reduce plasama blowby.

Hybrid armature projectile

Ionic polymers or solid polyelectrolytes in functionally- graded composite form with a conductive phase such as a metal, conductive polymer or graphite, when swollen and suitably plated by conducting electrodes, display a spontaneous curvature increasing with the applied electric field E. There also exists an inverse effect, where an imposed deformation induces an electric field (in open circuit conditions) in such ionic polymer conductive composites (IPCC). Presented here is a description of these effects in the linear regime, based on linear irreversible thermodynamics, with two driving forces, namely the electric field E and a water pressure gradient (Delta) p and two fluxes, namely the electric current density J and water current density Q. Presented are also some qualitative estimates of the four Onsager coefficients which play important roles in the proposed model.

Electromechanical modeling of ionic polymer conductive composite (IPCC) artificial muscles

In this paper we present an extended summary of the fundamental properties and characteristics of Ionic Polymeric-Metal Composites (IPMCs) as biomemetic sensors, actuators, and artificial muscles. Als, the phenomenological modeling of the underlying sensing and actuation mechanisms in IPMCs is presented based on linear irreversible thermodynamics with two driving forces; an electric field and a solvent pressure gradient and two fluxes, electric current and solvent flux. The importance of capacitors which arise from nanoparticles residing at the surface/subsurface of IPMCs is also discussed. We also present some quantitative experimental results on the Onsager coefficients.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Ionic polymer-metal composites: fundamentals and phenomenological modeling

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