Laser displacement sensor

As an example, consider the design of a simple conveyor mechanism, depicted in Fig. 5.3, built from multiple DEAs that will push a small cylindrical object forward. One solution is to use a central controller to coordinate the behavior of each actuator. Without feedback, the timing of actuation of each DEA would need to follow a predetermined pattern. However, as the object accelerates, or if objects with different masses or rotational inertias are transported, it would be difficult to ensure synchronized actuation in such an inflexible system. To improve flexibility, feedback from each actuator is required. Typically this would involve conventional external sensors, e.g., laser displacement sensors, LVDTs, optical encoders, or motion sensors, and the use of a centralized controller to coordinate the overall... 

Experiments have been conducted to validate the impedance and actuation models for IPMCs. The experimental setup is illustrated in Fig. 4.5. A cantilevered IPMC beam was placed in a small water tank and its tip displacement was measured with a laser displacement sensor (OADM 20I6441/S14F, Baumer Electric). The IPMC was subject to a voltage input generated from a dSPACE system (DS1104, dSPACE Inc.), and its current was measured for the validation of the impedance model. 

In the experiments, several aspects of the actuators were tested as a part of the evaluation. As depicted in Fig. 7.18, the experimental setup was designed to measure the linear motion of the actuator. A load on the output shaft of the actuator can verify the output force. The displacement of the actuator was measured with a laser displacement sensor (LK-081 Keyence) and the data were collected in a computer via a Universal Serial Bus (USB). 

Fig. 8.6 Demonstration of electrical feedthrough coupling under a square-wave actuation voltage (a) Bending displacement measured by the laser displacement sensor (b) sensing output from the PVDF. Reprinted from [Chen et al. (2007a)].

Thickness mea ring device with a laser Displacement sensor and a laser emitting device... 

The experimental setup for measuring eleetromechanical performance of an IPMC actuator consists of a clamp to mount the IPMC sample, a data recording device (e.g., digital oscilloscope or computer equipped for data acquisition), a function generator, a current amplifier, a force sensor, and a laser displacement sensor or a video camera (Figs. 4 and 5). The process diagram of electromechanical characterization is given in Fig. 6. 

Fig. 7 Positioning of IPMC and (a) laser displacement sensor or (b) force sensor...

Video cameras can also be implemented to measure the bending amplitude of an IPMC (Fig. 4b). The biggest advantage of using a video camera is the possibility to record the mechanical response of the whole shape of the actuator. However, extracting relevant data from the video can be rather complicated, especially in comparison with laser displacement sensor. However, the state of the art of video imaging systems and their built-in functionality are rapidly... 

In laser-optic measurement systems (such as Optalign), a combined laser source -sensor unit is placed on the reference shaft and the relative displacement vector and the alignment angle is calculated from the position of the incoming laser beam reflected by a prism unit, which is attached to the other shaft. This is an optical counterpart of the rim-and-face method. It is thus also relative, contact, manual and static in nature. 

Experiments were conducted to calibrate the PVDF sensor. To avoid the influence from the actuation voltage, we simply tapped the composite beam tip and measured simultaneously the charge amplifier output and the tip displacement. The displacement was measured with a laser distance sensor (OADM 20I6441/S14F, Baumer Electric, Southington, CT). Fig. 8.3(a) shows the measured charge response under the damped beam oscillation at 42 Hz, while Fig. 8.3(b) depicts the measured charge vs. the actual displacement, from which we can conclude that the beam tip displacement can be well captured by the PVDF sensor. 

Experiments were conducted to measure the stiffness of an IPMC beam and two IPMC-PVDF composite beams with different insulating layer thickness (30 pm vs. 100 pm). The two composite beams were named IPMC/PVDFl and IPMC/PVDF2, respectively. As illustrated in Fig. 8.5(a), the cantilevered beam under measurement was pushed quasi-statically at the tip by a linear actuator. Between the linear actuator and the tip was a PVDF-based micro force sensor measuring the interaction force. The tip displacement was measured with a laser distance sensor. Fig. 8.5(b) shows the measured tip displacement together with the corresponding force for each beam, with the spring constants determined to... 

Figure 10 shows the verification result of tire sensor function. The strip of the IPMC was fixed as a cantilever and was deformed manually. Its deformation was measured by a laser displacement meter, and tire output voltage was pre-amplified and measured. The size of the strip used in tire experiment was 20 x 2 mm and 0.2 mm of thickness. From tire result, the ou ut signals arise through the deformation of the strip, and the magnitude of tire ou ut signals is related to that of the... 

Reply by the Authors The paper shows five on-line monitoring results namely temperature, coefficient of friction, electrostatic sensor response, laser displacement probe response and specific wear rates. The wear displacement (wear curve) responses are from a laser probe that monitored the disc wear track. 

The operation of proximity sensors can be based on a wide range of principles, including capacitance, induction, Hall and magnetic effects variable reluctance, linear variable differential transformer (LVDT), variable resistor mechanical and electromechanical limit switches optical, photoelectric, or fiber-optic sensors laser-based distance, dimension, or thickness sensors air gap sensors ultrasonic and displacement transducers. Their detection ranges vary from micrometers to meters, and their applications include the measurement of position, displacement, proximity, or operational limits in controlling moving components of valves and dampers. Either linear or angular position can be measured ... 

One finds experimentally that the amplitudes of the displacements associated with a flexural wave of given total power are large relative to those of the other acoustic sensors discussed here. Peak-to-peak normal displacements up to 100 nm have been measured, using laser diffraction, when only a few milliwatts of wave energy were propagating in a plate a few micrometers thick. As a result of... 

An attractive feature of fiber sensors is the possibility of performing in vivo tests and monitoring. Numerous fiber-optic sensors have already been described that measure physical parameters of the human body [41]. Pressure, temperature, physiological flow, strain, motion, displacement, or flow velocity can be monitored by optical methods such as variable reflection, laser Doppler velocimetry, optical holography, or diffraction. In this section the application of optosensing methods to the determination of molecular species encountered in clinical and biomedical analysis is described. 

When the units are rotated from Position 3 to Position 4 in the horizontal direction, the laser dot moves perpendicularly to the previous direction on the laser sensor (alignment angle detection direction) and the vertical component of the alignment angle is computed, independently from the displacement vector. 

The accelerometer is a transducer designed to measure vertical acceleration and used to establish the inertial reference and effectively the response of the vehicle to the road surface (instant height of accelerometer in the host vehicle). The vertical distance between the accelerometer and the travelled surface is measured by displacement transducers or sensors (laser, acoustic or infrared sensors) and the distance travelled by distance transducers. Eigure 16.29 shows an accelerometer and a single sensor mid-mount on a vehicle. 

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