Untethered Microrobots With Serpentine Actuators: The Role of Elastics Point Contact & Laser Beam Shape on Their Locomotion

2021 ◽  
Author(s):  
Sri Sukanta Chowdhury ◽  
Zhong Yang ◽  
Patrick W. Clapacs ◽  
Dan O. Popa
Keyword(s):  
Thermal Expansion ◽  
Laser Beam ◽  
Point Contact ◽  
Laser Spot ◽  
Step Size ◽  
Stick Slip ◽  
Beam Shape ◽  
Slip Step ◽  
Resonance Frequencies ◽  
Depth Analysis

Abstract FEA simulations of 7 microrobots designed from asymmetric Chevron actuators are presented with in depth analysis of their resonance behavior due to fixed, as well as elastic supports at their contact points with underlying substrate. Experimental resonance frequencies of 3 different designs identified by frequency sweep experiments, excited by a 532 nm pulse laser, are in close agreement with the simulated values. Contact stiffness is estimated by comparing simulated and experimental resonance frequencies. Both in-plane and out of plane motion due to resonance is found in all of these structures that can be used to predict the stick-slip step size (locomotion mechanism) of these robots. In addition, modeling of differential thermal expansion is conducted to optimize the laser spot size that is used to drive these microrobots. Simulations of elliptic and circular laser spots with varying size suggest that covering only the actuators of the robot is sufficient for successful actuation. Using a circular laser spot increase the thermal expansion of the overall microrobot by 3.3 nm resulting in no significant gain in step size/gait of the robotic locomotion. This finding proves that the shape and size of the laser spot are insignificant as long as the actuators are under the laser beam.

Split beam method for determining mode shapes of cantilever beams under multiple loading conditions

2021 ◽  
pp. 107754632110276
Author(s):  
Jun-Jie Li ◽  
Shuo-Feng Chiu ◽  
Sheng D Chao
Keyword(s):  
Operation Mode ◽  
Point Contact ◽  
Mode Shapes ◽  
Cantilever Beams ◽  
Loading Conditions ◽  
Mechanical Responses ◽  
Relative Contribution ◽  
Resonance Frequencies ◽  
Beam Method ◽  
Multiple Loading

We have developed a general method, dubbed the split beam method, to solve Euler–Bernoulli equations for cantilever beams under multiple loading conditions. This kind of problem is, in general, a difficult inhomogeneous eigenvalue problem. The new idea is to split the original beam into two (or more) effective beams, each of which corresponds to one specific load and bears its own Young’s modulus. The mode shape of the original beam can be obtained by linearly superposing those of the effective beams. We apply the split beam method to simulating mechanical responses of an atomic force microscope probe in the “dynamical” operation mode, under which there are a stabilizing force at the positioner and a point-contact force at the tip. Compared with traditional analytical or numerical methods, the split beam method uses only a few number of basis functions from each effective beam, so a very fast convergence rate is observed in solving both the resonance frequencies and the mode shapes at the same time. Moreover, by examining the superposition coefficients, the split beam method provides a physical insight into the relative contribution of an individual load on the beam.

ORIENTATING MANIPULATION OF CYLINDRICAL PARTICLES WITH OPTICAL TWEEZERS

2008 ◽  
Vol 17 (04) ◽  
pp. 387-394 ◽  
Author(s):  
XIUDONG SUN ◽  
XUECONG LI ◽  
JIANLONG ZHANG
Keyword(s):  
Escherichia Coli ◽  
Carbon Nanotubes ◽  
Laser Beam ◽  
Optical Tweezers ◽  
Optical Trap ◽  
Polarization Direction ◽  
Beam Shape ◽  
E Coli ◽  
Potential Applications ◽  
Cylindrical Particles

Orientating manipulations of cylindrical particles were performed by optical tweezers. Vertical and horizontal manipulations of Escherichia coli (E. coli) were carried out by changing the trapping depth and the focused laser beam shape. It was found that carbon nanotubes bundles (CNTBs) could be rotated in the linear polarized optical trap until it orientated its long axis along the linear polarization direction of the laser beam. However, E.coli could not be orientated in this way. Corresponding mechanisms were discussed based on the anisomeric electric characters of CNTBs. These orientation technologies of cylindrical objects with optical trap have potential applications in assembling nano-electric devices.

Effect of laser beam shape parameters on photothermal deflection densitometers

1984 ◽  
Vol 56 (9) ◽  
pp. 1674-1677 ◽  
Author(s):  
Tsuey Ing. Chen ◽  
Michael D. Morris
Keyword(s):  
Laser Beam ◽  
Shape Parameters ◽  
Beam Shape ◽  
Photothermal Deflection

Dynamic control of laser beam shape for heat treatment

2018 ◽  
Vol 30 (3) ◽  
pp. 032507 ◽  
Author(s):  
Paula Sancho ◽  
M. Angeles Montealegre ◽  
Jesús Dominguez ◽  
Piera Alvarez ◽  
Juan Isaza
Keyword(s):  
Heat Treatment ◽  
Laser Beam ◽  
Dynamic Control ◽  
Beam Shape

STUDYING THE CONTACT POINT AND INTERFACE MOVING IN A SINUSOIDAL TUBE WITH LATTICE BOLTZMANN METHOD

2001 ◽  
Vol 15 (09) ◽  
pp. 1287-1303 ◽  
Author(s):  
HAI-PING FANG ◽  
LE-WEN FAN ◽  
ZUO-WEI WANG ◽  
ZHI-FANG LIN ◽  
YUE-HONG QIAN
Keyword(s):  
Boundary Conditions ◽  
Contact Line ◽  
Lattice Boltzmann ◽  
Complex Geometry ◽  
Contact Point ◽  
Point Contact ◽  
Immiscible Fluids ◽  
Lattice Boltzmann Model ◽  
Stick Slip ◽  
Bounce Back

The multicomponent nonideal gas lattice Boltzmann model by Shan and Chen (S-C) is used to study the immiscible displacement in a sinusoidal tube. The movement of interface and the contact point (contact line in three-dimension) is studied. Due to the roughness of the boundary, the contact point shows "stick-slip" mechanics. The "stick-slip" effect decreases as the speed of the interface increases. For fluids that are non-wetting, the interface is almost perpendicular to the boundaries at most time, although its shapes at different position of the tube are rather different. When the tube becomes narrow, the interface turns a complex curves rather than remains simple menisci. The velocity is found to vary considerably between the neighbor nodes close to the contact point, consistent with the experimental observation that the velocity is multi-values on the contact line. Finally, the effect of three boundary conditions is discussed. The average speed is found different for different boundary conditions. The simple bounce-back rule makes the contact point move fastest. Both the simple bounce-back and the no-slip bounce-back rules are more sensitive to the roughness of the boundary in comparison with the half-way bounce-back rule. The simulation results suggest that the S-C model may be a promising tool in simulating the displacement behaviour of two immiscible fluids in complex geometry.

Laser spot size and scaling laws for laser beam additive manufacturing

2022 ◽  
Vol 73 ◽  
pp. 26-39
Author(s):  
Jordan S. Weaver ◽  
Jarred C. Heigel ◽  
Brandon M. Lane
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Scaling Laws ◽  
Spot Size ◽  
Laser Spot ◽  
Laser Spot Size

A Novel Three-Dimensional Finite Element Model to Simulate Third Body Effects on Fretting Wear of Hertzian Point Contact in Partial Slip

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Arman Ahmadi ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Three Dimensional ◽  
Point Contact ◽  
Fretting Wear ◽  
Partial Slip ◽  
Wear Particles ◽  
Third Body ◽  
Stick Slip ◽  
The Third

Abstract In this investigation, a finite element (FE) model was developed to study the third body effects on the fretting wear of Hertzian contacts in the partial slip regime. An FE three-dimensional Hertzian point contact model operating in the presence of spherical third bodies was developed. Both first bodies and third bodies were modeled as elastic–plastic materials. The effect of the third body particles on contact stresses and stick-slip behavior was investigated. The influence of the number of third body particles and material properties including modulus of elasticity, hardening modulus, and yield strength were analyzed. Fretting loops in the presence and absence of wear particles were compared, and the relation between the number of cycles and the hardening process was evaluated. The results indicated that by increasing the number of particles in contact, more load was carried by the wear particles which affect the wear-rate of the material. In addition, due to the high plastic deformation of the debris, the wear particles deformed and took a platelet shape. Local stick-slip behavior over the third body particles was also observed. The results of having wear debris with different material properties than the first bodies indicated that harder wear particles have a higher contact pressure and lower slip at the location of particles which affects the wear-rate.

Development of a 3-DOF Tripedal Stick-Slip Microrobotic Mobile Platform for Unconstrained, Omnidirectional Sample Positioning

2018 ◽  
Author(s):  
Iman Adibnazari ◽  
William S. Nagel ◽  
Kam K. Leang
Keyword(s):  
Visual Servoing ◽  
Feedforward Control ◽  
Low Cost ◽  
Tracking Error ◽  
Kinematic Model ◽  
Open Loop ◽  
Step Cycle ◽  
Stick Slip ◽  
Slip Step ◽  
Forward Kinematic

This paper presents the development of a piezo-based three-degree-of-freedom (3-DOF), tripedal microrobotic platform that allows for unlimited travel with sub-micron precision over a planar surface. Compliant mechanical amplifiers are incorporated with each piezoelectric stack actuator to improve both the stroke and load-bearing capability of the platform. A forward kinematic model of the stage based on its tripedal leg architecture is derived for each stick-slip step cycle and inverted for feedforward control of the platform. A prototype is constructed using low-cost 3D-printing techniques. Experimental results demonstrate actuator stroke of 29.4 μm on average with a dominant resonance of approximately 860 Hz. Results demonstrate the stage tracks a 3 mm by 3 mm square trajectory in open loop. Feedback control through visual servoing is then simulated on a model that includes flexure dynamics, observed surface interactions, and camera sampling times, reducing the root-mean-square (RMS) tracking error by 90%. This control scheme is then implemented experimentally, resulting in 99% RMS position error reduction relative to when only feedforward control is used.

Influence of Excimer Laser Beam Shape on Poly-Si Crystallisation

2004 ◽  
Vol 43 (8A) ◽  
pp. 5114-5121 ◽  
Author(s):  
S. D. Brotherton ◽  
D. J. McCulloch ◽  
J. P. Gowers
Keyword(s):  
Laser Beam ◽  
Excimer Laser ◽  
Beam Shape
Sign in / Sign up

Export Citation Format

Share Document