Dimensioning of the Actuators

The technical design of the splint and the related dimensioning of the actuators have necessarily to take into account, as a fundamental specification, the maximum antagonist force that the actuators should be able to offer. An analysis of the state-of-the-art of hand splints for finger rehabilitations showed a chronic lack of extensive and comparable data on suitable rehabilitation forces adopted in the clinical practice. However, as a special case. 

To satisfy this requirement, both the number of actuators to be used, their size, their constituent material and the performances achievable from each of them should be considered. This work adopted a standard type of prototype folded actuator currently being fabricated in our laboratory these are characterized hy do = 1 mm and Ao =16 x 21 mm. According to their typical performances [14], A = 3 parallel devices were used. 

The structure of the developed splint (reported in the next section) allowed a maximum length for the actuators of 96 mm, while a maximum flexion corresponding to (L Lo)max = 10 mm was considered accordingly, Lq = 85 mm was used. 

---

The blocking force of a bending IPMC actuator is also dependent on the position of force sensor head as well as flie dimensions of the actuator (Anton et al. 2008). For the purpose of physical modeUng, it is useful to convert the blocking force F into... 

A miniaturized Fourier transform spectrometer for near-infrared measurements (FTIR, 2500-8330 nm) was developed at the Forschungszentrum Karlsruhe [120], Near-infrared measurements give information, for example, about the oil, water and protein content of liquids or solids. The dimensions of the detector chip are 11.5 x 9.4 mm, the device is essentially a miniaturized Michelson interferometer and it consists of a micro optical bench with beamsplitter, ball lenses, mirrors and the detector chip. The light beam is coupled in via a glass-fiber and an electromagnetic actuator. The signal is derived from the signal response of the detector by Fourier transformation. 

The characteristics of the actuators, check valves and micropumps which have been used in flow systems are listed in Table 3, Table 4, and Table 5 respectively. The characteristics depend on the dimensions designed so that these are only typical values. 

FIG. 1 Schematic representation of the tracking device. The piezoelectric actuator, which keeps the focali/alion constant and allows one to access the third dimension of the motion, can be mounted either on the cell (a) or on the objective (b). 

In ideal world, one might modulate the adhesion energy of the valve seat to achieve the desired performance for a specific set of dimensions. This would likely be difficult as the chemistry of the fluidic environment, which obviously depends on the application, often affects interface toughness. However, one can measure the interface toughness for a given application and then choose the dimensions of the chambers to satisfy Equation 39.34 the result is a check valve that actuates to a specific clearance for a given interface condition. 

Kofod used advanced materials models in an attempt to elucidate the effects that prestrain have on the actuation performance of a simple cuboid DE actuator [183]. The results are purely phenomenological however, they indicate that in the special case of a purely isotropic amorphous material, prestrain does not affect the electromechanical coupling directly. The enhancement in actuation strain due to prestrain occurs through the alteration of the geometrical dimensions of the acmator. Kofod also determined that the presence of an optimum load is related to the plateau region in the force-stretch curve and that prestrain is not able to affect the location of this region. 

Periodic and aperiodic microstructures prepared by lithography form the basis for a vast number of applications such as electronic circuits, sensors, actuators, etc. (1,2). As the dimensions of the structures are pushed to ever smaller limits, size dependent quantum effects are encountered opening new fields of interesting physics and... 

In the simulation, all the dimensions of the inactive-regions (boundary widths) of the actuator are 0.5 mm, while the areas and thicknesses of the active region are similar to those for the circular actuator. According to the simulation results shown in Fig. 7.11, the trapezoidal actuator exhibits bet-... 

First, the deformations of the three prototypes of actuator were measured. As shown in Fig. 7.19, the performance of the trapezoidal actuator is better than those of the other actuators. These results are consistent with the analysis results. Consequently, the dimension of the free boundary of the actuator layer determines the deformation of the multi-stacked actuator. 

A square-wave voltage input of 3.3 V was applied to the IPMC at different frequencies. As shown in Fig. 9.5, the model was able to predict the speed of the robotic fish as a function of the actuation frequency, for all different tails. In particular, it correctly predicted the peak in each speed-frequency curve. At relatively low frequencies, the robot speed increases with the actuation frequency. As the frequency increases, the bending amplitude of the IPMC actuator decreases, which ultimately results in a decreased speed for the robot. Therefore, there is an optimal actuation frequency for producing the largest speed for the robotic fish. Prom Fig. 9.5, both the optimal frequency and the peak speed vary with the tail dimensions, which is well captured by the model. 

CAD and dimensions of the first hybrid-architecture telesurgery master prototype arm with handle actuator fixed on the base and remotely actuated handle. 

The most diffused actuating configuration, in which these materials are used, is represented by the so-called unimorph bilayer bender. This kind of actuator consists of a film of active material coupled to a passive supporting layer. The bilayer structure is operated within an electrochemical cell, having a liquid electrolyte in which the device is immersed. The active polymeric layer of the actuator works as one electrode of the cell, while a counter electrode and a third reference electrode are separately immersed in the electrolyte. One end of the bilayer is constrained, while the other is free. The potential difference applied between the electrodes causes red-ox reactions of the conducting polymer. Since the CP and the passive layers are mechanically interlocked, when the polymer swells/shrinks the passive layer, which can not modify its dimensions, transforms the CP linear displacement into a bending movement of the structure [238-242]. Very similar is the bimorph structure. In this case the passive layer is substituted by a second CP film and they work in opposition of phase. 

---