Design and analysis of piezoelectric actuators having over 20% effective strain using an exponential amplification mechanism are presented in this paper. Piezoelectric ceramic material, such as lead zirconate titanate (PZT), has large stress bandwidth, but its extremely small strain, i.e., only 0.1%, been a major bottleneck for broad applications. This paper presents new design, called "nested rhombus" multilayer mechanism, that increases exponentially through hierarchical cellular...

Wound healing is the complex physiological process of restoring skin's integrity, structure, and function after damage caused by external conditions. The wound cascade may be altered due to progression certain diseases, such as diabetes, venous hypertension, or peripheral arterial disease, resulting in non-healing chronic wounds. Chronic wounds can characterized a wide variety pathologies including increased reactive oxygen species, ineffective neutrophil activity, overabundance...

A new approach to a variable stiffness actuator with tunable resonant frequencies is presented in this paper. Variable actuators have become increasingly important meet safety requirements and achieve adaptive manipulation or locomotion. For cyclic motion, exploiting dynamic resonance can lead high power transmission, energy efficiency, large motion amplitude. Resonance characteristics yet be incorporated into single design. In paper, cellular artificial muscle that achieves both...

Abstract Shape memory polymer (SMP) systems exhibiting semicrystalline- elastomer blends, such as thermoplastic polyurethane and polylactic acid have been well studied, but their use in biomedical shape applications has limited by high activation temperature. SMPs are capable of deformation recovery through the an external stimuli, Critical criteria for used is achieving a stimulus temperature close to 37°C while still experiencing sufficient recovery. A polymer’s glass transition defined...

The demand for high-force and compact actuators with large strain is increasing in robotics. PZT known as one of the promising materials this purpose respect to bandwidth, stress, reliability. However, most critical drawback its extremely small strain, i.e. only 0.1 %. This paper presents a nested rhombus structure amplification stack actuators. provides "power-law" amplification, resulting over 20 % which particularly useful gaining body, appropriate many robotic applications. notational...

Sutures are ubiquitous medical devices for wound closures in human and veterinary medicine, suture techniques frequently evaluated by comparing tensile strengths ex vivo studies. Direct nondestructive measurement of force present sutured biological skin tissue is a key challenge biomechanical fields because the unique complex properties each specimen lack compliant sensors capable monitoring large levels strain. The authors have recently proposed soft elastomeric capacitor (SEC) sensor that...

Piezoelectric ceramic material, such as Lead Zirconate Titanate (PZT), has large stress and bandwidth, but its extremely small strain, i.e. only 0.1%, been a major bottleneck for broad applications. We have proposed “nested rhombus” multi-layer mechanism PZT actuators, which increases strain exponentially through hierarchical cellular structure, over 20% effective strain. To drive load, however, care must be taken in the design of amplification structure. Through kinematic static analysis...

A static lumped parameter model is proposed for the design and analysis of nested piezoelectric cellular actuators with exponential strain amplification mechanisms. Piezoelectric ceramic material, such as Lead Zirconate Titanate (PZT), has large stress bandwidth, but its extremely small strain, i.e. only 0.1%, been a major bottleneck broad applications. We have "nested rhombus" multi-layer mechanism PZT actuators, which increases exponentially through hierarchical structure, over 20%...

This paper presents the dynamic analysis of an artificial muscle actuator designed for high-bandwidth, power-law strain amplification. The is based on a nested cellular architecture PZT stack actuators. Most smart material actuators have seen limited use in mobile robotic applications because their small strain, low stress capacity, bandwidth, and stringent input requirements. proposed design overcomes these limitations can serve as high-bandwidth multifunctional muscle. characteristics are...

A simple and efficient approach for varying the inherent stiffness impedance of a muscle-like actuator is presented. The basic architecture PZT cellular actuators has already achieved large effective strain (10-20%). This modified extended so that each unit can be switched between zero compliance state constant state. varied by changing distribution units in rigid versus compliant Furthermore, placing multitude these series or parallel, vary within set discrete values. paper also...

Variable stiffness actuation and energy harvesting have been important yet separate challenges in robotics. Both functions are needed, however, for mobile robots on extended missions when actuators generators must be used together. In this paper, we present a unique piezoelectric cellular system that combines motion generation capabilities into single, scalable device. Each of the discrete units provides linear, contractile at 10% strain using converse effect. These may also back-driven from...

This paper describes the design and analysis of a humanoid foot constructed using polypyrrole (PPy) conducting polymer (CP) actuators. The compliance damping natural muscles plays an important role in human gait. Conducting polymers actuators other smart structure can store energy by means inherent mechanical that traditional DC motor do not possess. presents method for optimizing order to minimize active control effort required generate A simplified kinematic model is evaluated...

Our aim was to assess three-dimensional kinematic motion analysis as an objective diagnostic tool for the characterization of movement disorder Shivers in horses. Kinematic parameters were measured three horses with and compared a control group four normal Multiple parameter differences found at walk, during backing, when asked pick up their hindlimbs. Most significant changes wider hindlimb stance 0.39 ± 0.15 m increased abduction angle 48.7 7.52° hoof elevation (0.77 0.08 left 0.94 0.11...

Abstract Resonance is known to reduce the input energy requirements of various actuator systems. The favorable effects resonance, however, are limited a narrow frequency range. To overcome this limitation, we describe general framework for using discrete units inertia that can be activated in binary sense move resonant across desired We also enumerate generalized physical cases which actuators energetically benefit from resonance. develop closed-form optimal results idealized case two...

A state observer for estimating and predicting the internal of polypyrrole conducting polymer actuators is presented. Polypyrrole can produce large stresses (>5 MPa) with associated strains (>12%), which leads to a high energy density. However, care must be taken since polymers degrade quickly when exposed overcharged or over-strain conditions. Unfortunately, charge other variables relevant degradation actuator material are not directly measurable in real-time control systems. To cope this...

Regenerative life support systems for large space stations to achieve capability operation over extended periods of time

In thermosetting composite manufacturing, part thickness, mold temperature, pressure, and resin kinetics can affect the uniformity of cure in finished part. If interaction these parameters is not accounted for, then unwanted overshoot processing temperature occur within a during cure. this paper, relationship between material was considered to establish critical thickness separating parts having large overshoots from small overshoots. The one-dimensional heat equation with an autocatalytic...

This paper presents the design and analysis of a novel variable stiffness resonance actuator based on cellular arrangement piezoelectric devices.The muscle concept is presented followed by general dynamic model for establishing theoretical bounds achievable resonant frequencies.A that specific to proposed then formulated include effects parasitic dynamics.The characteristics three cell prototype system are identified experimentally.The experimental results agree over large frequency range...

In this paper the design and static analysis of a novel artificial muscle system are presented. The proposed is based on exponential strain amplification applied to PZT stack actuators. Exponential achieved by means nested cellular architecture. primary limitation mechanisms loss blocking force due structural compliance. Therefore, quantify improve performance design, analytical expressions obtained for free displacement two separate using Castigliano's energy theorem. Measured values...