Mechanically adaptive actuators

Collecting a sample actuation from a canister is performed as a multi-step sequence. First, the canister is placed into an adapter sleeve. The sleeve, along with the canister, is then placed into the actuator gripper. The sleeve is then agitated by swiveUing it to a horizontal position and back. Next, the canister adapter mechanism and dose actuation chamber are lowered. At this, point the canister is positioned inside the dose actuation chamber and the dose actuation chamber rests on top of a sample container. The canister is then actuated by the dosing cyhnder. Finally, the sleeve/canister assembly is raised from the dose actuation chamber and is ready to be re-actuated or unloaded. 

Smart and adaptive or intelligent materials adjust their mechanical properties upon the receipt of an external stimulus. In engineering language, they act as integrated sensors, processors, and actuators. For example, some polymers can be considered to be smart since they change their shapes with a change of temperature [3] this property has been exploited in the development of all-... 

Figure 7.120 is a simplified view of a spring diaphragm actuator. The actuator receives a pneumatic signal from the controller via a booster flow enlarger or a valve positioner and can be adapted in the form of an air-to-open or an air-to-close mechanism. 

Then, the healthy signal is used to feed a bank of /Vp + 1 nonlinear adaptive observers (where /Vp is the number of the possible process/actuator faults). The first observer is in charge of detecting the occurrence of process/actuator faults. The other /Vp observers, each corresponding to a particular type of process/actuator fault, achieve fault isolation and identification by adopting a suitable adaption mechanism. Figure 6.3 shows a block diagram representation of the overall architecture. 

Elevation of the priming lever compresses a spring above the base of the MDI. A mechanical obstruction prevents movement of the aerosol canister within the plastic moulding until the patient inhales. Inhalation rotates a small vane within the mouthpiece, removing the obstacle and allowing the aerosol canister to move down sufficiently to actuate the MDI. Unscrewing the removable sleeve can open the Autohaler. This allows the MDI to be removed and the mouthpiece adapter to be washed (68). 

Cox, A., DJ. Monopoli, and M. Goldfarb. 1999. Development of piezoelectrically actuated elasto-dynamic flapping micro-aerial vehicles. Pp. 257-262 in ASME International Mechanical Engineering Congress and Exhibition. AD-Vol. 59/MD-Vol. 87 Adaptive Structures and Materials Systems. New York ASME. 

Secondly, conjugated polymers were studied as biomimetic artificial muscles. A scalable physics based electro-chemo-mechanical model was developed to connect an input voltage to bending of the material. The reduced version of the model was used to design a robust adaptive controller. Also, a nonlinear mechanical model was investigated. Furthermore, a torsional actuator was developed by depositing PPy on a tube substrate with helically wound platinum fibers. A set of experiments were conducted to confirm the torsional and other actuation modes as well as the model. 

As shown in this section, organic SMP composites have been extensively used for their enhanced mechanical, electrical, and thermal properties. With speculative uses in self-healing applications [24], moisture-activated networks [40, 41], and other thermally and electrically actuated networks [42, 43], organic SMPCs demonstrate the capability to adapt neatly to the challenges presented by niche problems. However, the prime focus of this review is the loading of various inorganic fillers into SMP networks to tackle issues that are currently imattainable because of both the physical and cost limitations of organic fillers. 

Piezoelectric and electrostrictive devices have become key components in smart actuator systems such as precision positioners, miniature ultrasonic motors and adaptive mechanical dampers. This section reviews the developments of piezoelectric and related ceramic actuators with particular focus on the improvement of actuator materials, device designs and applications of the actuators. 

Figure 18 The synthetic strategy anployed to create a physicaUy bound phototesponsive actuator (a), the UV-induced macroscopic behavior (b), and the proposed mechanism on UV-light irradiation (c). (Adapted with pamission from Ref. 52. Elsevier, 2005.)...

Materials that allow an intelligent or smart structure to adapt to its environment are known as actuators. These materials have the ability to change the shape, stiffness, position, natural frequency, damping, friction, fluid flow rate, and other mechanical characteristics of adaptronic structures in response to changes in temperature, electric field, or magnetic field. The most common actuator materials are shape memory alloys, piezoelectric materials, mag-netostrictive materials, electrorheological fluids, and magnetorheological fluids [2]. Actuators with these materials will be described in detail in Sects. 6.2 to 6.6 therefore you will find only a brief overview below. 

The two-way effect will be stabihzed after 20... 100 thermal and mechanical cycles. Due to the ability of the martensite (low-temperature phase) to form a twinned crystalline structure, different areas of the actuator element may be strained in different ways extension, compression, or shear are deformations that will be reverted to by heating. This variety offers the interesting opportunity to adapt the actuators shape change to the special needs of the actuating task. By this means, transmission links or gears may be eliminated, which helps reduce the size and price of a system. 

SM actuators may have very many different shapes and offer a variety of shape changes (i. e. actuator strokes). This property can be exploited so as to adapt the SM elements shape to the actuating task. As an application example, a miniature parallel gripper with electrically heated SM wires integrated into its mechanical structure was presented. Further on the performance of pseudo-elastic shape memory flexure hinges in parallel robots for micro-assembly tasks was shown. The future opportunity for thin-fllm SM actuators to drive micromechanical systems and devices was demonstrated by a miniature silicon gripper. 

In adaptive and sensory structures passive piezoelectric sensors are ap>-plied to measure the conditions (e.g. strain, mechanical stress, speed, acceleration, frequency) and the properties (e.g. stiffness, damping and eigen-modes) of the structure. This is a way to determine the deviation of the requested actuating variable and to initiate an appropriate feedback to the actuators. 

Shape control and active flow, the mainly static deformation of space and aerodynamic structures to either improve communication performance of antennas or adapt structures to optimum aerodynamic fluid flow, both achieved by integrated actuation mechanisms. 

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