Foot-Terrain Interaction for a Prototype Silicon Micro-Robot

2011 ◽  
Author(s):  
Jeong Hoon Ryou ◽  
Kenn Oldham
Keyword(s):  
Analytical Model ◽  
Experimental Testing ◽  
Contact Forces ◽  
Experimental Comparison ◽  
Small Scale ◽  
Simulation Studies ◽  
Static Charge ◽  
Micro Robot ◽  
Robot Evaluation ◽  
Robot Leg

Research on dynamics of micro devices indicates that contact forces are complex in a micro-scale environment. Previous work tried to identify how small-scale forces numerically affect a walking micro system, using a similar structure to a micro-robot leg and a simple analytical model for system dynamics. This paper extends that work by focusing on further experimental testing and simulation studies on a prototype micro-robot. Evaluation of experimental data indicates that characteristics of the ground, such as material properties and static charge on the surface should be also considered in understanding foot-terrain interaction. This leads to modifications to the former foot-terrain interaction algorithm. The refined analytical model is validated through experimental comparison.

A Theoretical and Experimental Comparison of Optimizing Angle of Twist Using BET and BEMT

2012 ◽  
Author(s):  
Timothy A. Burdett ◽  
Kenneth W. Van Treuren
Keyword(s):  
Experimental Testing ◽  
Element Model ◽  
Experimental Comparison ◽  
Speed Ratio ◽  
Small Scale ◽  
Blade Element Theory ◽  
Wind Speeds ◽  
Subsonic Wind Tunnel ◽  
Element Theory ◽  
Blade Element

Wind turbines are often designed using some form of Blade Element Model (BEM). However, different models can produce significantly different results when optimizing the angle of twist for power production. This paper compares the theoretical result of optimizing the angle of twist using Blade Element Theory (BET) and Blade Element Momentum Theory (BEMT) with a tip-loss correction for a 3-bladed, 1.15-m diameter wind turbine with a design tip speed ratio (TSR) of 5. These two theories have been chosen because they are readily available to small-scale designers. Additionally, the turbine was scaled for experimental testing in the Baylor Subsonic Wind Tunnel. Angle of twist distributions differed by as much as 15 degrees near the hub, and the coefficient of power differed as much as 0.08 for the wind speeds tested.

scholarly journals Experimental Comparison of Direct and Active Throttle Control of a 7 kW Turboelectric Power System for Unmanned Aircraft

2021 ◽  
Vol 11 (22) ◽  
pp. 10608
Author(s):  
Johnathan Burgess ◽  
Timothy Runnels ◽  
Joshua Johnsen ◽  
Joshua Drake ◽  
Kurt Rouser
Keyword(s):  
Transient Behavior ◽  
Unmanned Aircraft ◽  
Experimental Comparison ◽  
Small Scale ◽  
Unmanned Aerial Systems ◽  
Operational Parameters ◽  
Turbine Engine ◽  
Control Scheme ◽  
Aerial Systems ◽  
Electric Loads

This article compares direct turbine throttle control and active turbine throttle control for a turboelectric system; the featured turboprop is rated for 7 kW of shaft output power. The powerplant is intended for applications in unmanned aerial systems and requires a control system to produce different amounts of power for varying mission legs. The most straightforward control scheme explored is direct turbine control, which is characterized by the pilot controlling the throttle of the turbine engine. In contrast, active control is characterized by the turbine reacting to the power demanded by the electric motors or battery recharge cycle. The transient response to electric loads of a small-scale turboelectric system is essential in identifying and characterizing such a system’s safe operational parameters. This paper directly compares the turbogenerator’s transient behavior to varying electric loads and categorizes its dynamic response. A proportional, integral, and derivative (PID) control algorithm was utilized as an active throttle controller through a microcontroller with battery power augmentation for the turboelectric system. This controller manages the turbine’s throttle reactions in response to any electric load when applied or altered. By comparing the system’s response with and without the controller, the authors provide a method to safely minimize the response time of the active throttle controller for use in the real-world environment of unmanned aircraft.

Experimental Testing and Numerical Modeling of Small-Scale Boat With Drag-Reducing Air-Cavity System

2021 ◽  
Author(s):  
Jeffrey M. Collins ◽  
Phillip R. Whitworth ◽  
Konstantin I. Matveev
Keyword(s):  
Adaptive Mesh Refinement ◽  
Experimental Testing ◽  
Hydrodynamic Performance ◽  
Small Scale ◽  
Video Monitor ◽  
Data Logger ◽  
Time Step ◽  
Experimental Conditions ◽  
Air Cavity ◽  
Air Supply

Abstract Hydrodynamic performance of ships can be greatly improved by the formation of air cavities under ship bottom with the purpose to decrease water friction on the hull surface. The air-cavity ships using this type of drag reduction are usually designed for and typically effective only in a relatively narrow range of speeds and hull attitudes and sufficient rates of air supply to the cavity. To investigate the behavior of a small-scale air-cavity boat operating under both favorable and detrimental loading and speed conditions, a remotely controlled model hull was equipped with a data acquisition system, video camera and onboard sensors to measure air-cavity characteristics, air supply rate and the boat speed, thrust and trim in operations on open-water reservoirs. These measurements were captured by a data logger and also wirelessly transmitted to a ground station and video monitor. The experimental air-cavity boat was tested in a range of speeds corresponding to length Froude numbers between 0.17 and 0.5 under three loading conditions, resulting in near zero trim and significant bow-up and bow-down trim angles at rest. Reduced cavity size and significantly increased drag occurred when operating at higher speeds, especially in the bow-up trim condition. The other objective of this study was to determine whether computational fluid dynamics simulations can adequately capture the recorded behavior of the boat and air cavity. A computational software Star-CCM+ was utilized with the VOF method employed for multi-phase flow, RANS approach for turbulence modeling, and economical mesh settings with refinements in the cavity region and near free surface. Upon conducting the mesh verification study, several experimental conditions were simulated, and approximate agreement with measured test data was found. Adaptive mesh refinement and time step controls were also applied to compare results with those obtained on the user-generated mesh. Adaptive controls improved resolution of complex shedding patterns from the air cavity but had little impact on overall results. The presented here experimental approach and obtained results indicate that both outdoor experimentation and computationally inexpensive modeling can be used in the process of developing air-cavity systems for ship hulls.

HE-YOLO: Aerial Target Detection Based On Improved YOLOv3

2021 ◽  
Author(s):  
Yuqing Zhao ◽  
Jinlu Jia ◽  
Di Liu ◽  
Yurong Qian
Keyword(s):  
Target Detection ◽  
Loss Function ◽  
Detection Rate ◽  
Aerial Image ◽  
Experimental Comparison ◽  
Small Scale ◽  
Detection Accuracy ◽  
False Detection Rate ◽  
False Detection ◽  
Bounding Box

Aerial image-based target detection has problems such as low accuracy in multiscale target detection situations, slow detection speed, missed targets and falsely detected targets. To solve this problem, this paper proposes a detection algorithm based on the improved You Only Look Once (YOLO)v3 network architecture from the perspective of model efficiency and applies it to multiscale image-based target detection. First, the K-means clustering algorithm is used to cluster an aerial dataset and optimize the anchor frame parameters of the network to improve the effectiveness of target detection. Second, the feature extraction method of the algorithm is improved, and a feature fusion method is used to establish a multiscale (large-, medium-, and small-scale) prediction layer, which mitigates the problem of small target information loss in deep networks and improves the detection accuracy of the algorithm. Finally, label regularization processing is performed on the predicted value, the generalized intersection over union (GIoU) is used as the bounding box regression loss function, and the focal loss function is integrated into the bounding box confidence loss function, which not only improves the target detection accuracy but also effectively reduces the false detection rate and missed target rate of the algorithm. An experimental comparison on the RSOD and NWPU VHR-10 aerial datasets shows that the detection effect of high-efficiency YOLO (HE-YOLO) is significantly improved compared with that of YOLOv3, and the average detection accuracies are increased by 8.92% and 7.79% on the two datasets, respectively. The algorithm not only shows better detection performance for multiscale targets but also reduces the missed target rate and false detection rate and has good robustness and generalizability.

An Improved Analytical Model of Friction and Ball Motion in Linear Ball Bearings With Application to Ball-to-Ball Contact Prediction

2018 ◽  
Author(s):  
Bo Lin ◽  
Molong Duan ◽  
Chinedum E. Okwudire ◽  
Jason S. Wou
Keyword(s):  
Analytical Model ◽  
Analytical Formula ◽  
Point Contact ◽  
Friction Model ◽  
Linear Velocity ◽  
Contact Forces ◽  
Ball Bearings ◽  
Friction Behavior ◽  
Rolling Ball ◽  
Ball Contact

The friction behavior of rolling ball machine components like linear ball bearings is very important to their functionality. For instance, differences in linear velocity of balls induces ball-to-ball contact in certain circumstances, resulting in significant increases and variations in friction. In this paper, an improved analytical formula for determining the linear velocity of balls in four-point-contact linear ball bearings is derived as a function of contact angle deviations and contact forces. The analytical formula is validated against a comprehensive friction model in the literature and shown to be in good agreement, while an oversimplified analytical model proposed by the authors in prior work is shown to be inaccurate. A case study is presented where insights gained from the derived analytical formula are used to mitigate velocity difference of balls in a linear ball bearing which otherwise would experience ball-to-ball contact.

Shunt Tuning of a Piezoelectric Cantilever Beam Resonator

2003 ◽  
Author(s):  
Muturi G. Muriuki ◽  
William W. Clark
Keyword(s):  
Stainless Steel ◽  
Piezoelectric Material ◽  
Analytical Model ◽  
Cantilever Beam ◽  
Lead Zirconate Titanate ◽  
Vibration Frequency ◽  
Experimental Testing ◽  
Lead Zirconate ◽  
Beam Resonator ◽  
Piezoelectric Cantilever

This paper presents the design and analysis of a cantilever beam resonator that is driven by a piezoelectric material. The beam is a bimorph structure with Lead Zirconate Titanate (PZT) and stainless steel or aluminum layers. The PZT layer is electroded in segments to form a sensor and actuator pair for feedback to drive the resonator. An additional PZT segment is used, in conjunction with a capacitive shunt circuit, to change the vibration frequency of the resonator. The study is based on an analytical model of the beam and experimental testing.

A Dynamic Service-Oriented Distributed Computing Framework for Evaluation of Computationally Expensive Black-Box Analyses

2014 ◽  
Author(s):  
George H. Cheng ◽  
Chao Qi ◽  
G. Gary Wang
Keyword(s):  
Distributed Computing ◽  
Service Oriented Architecture ◽  
Experimental Testing ◽  
Black Box ◽  
Small Scale ◽  
Distributed Computing Networks ◽  
Service Oriented ◽  
Computationally Expensive ◽  
Computing Framework ◽  
Load Balancing Algorithm

A practical, flexible, versatile, and heterogeneous distributed computing framework is presented that simplifies the creation of small-scale local distributed computing networks for the execution of computationally expensive black-box analyses. The framework is called the Dynamic Service-oriented Optimization Computing Framework (DSOCF), and is designed to parallelize black-box computation to speed up optimization runs. It is developed in Java and leverages the Apache River project, which is a dynamic Service-Oriented Architecture (SOA). A roulette-based real-time load balancing algorithm is implemented that supports multiple users and balances against task priorities, which is superior to the rigid pre-set wall clock limits commonly seen in grid computing. The framework accounts for constraints on resources and incorporates a credit-based system to ensure fair usage and access to computing resources. Experimental testing results are shown to demonstrate the effectiveness of the framework.

Seismic Performance of Vibration Control Device That Generates Power

2009 ◽  
Author(s):  
Taichi Matsuoka ◽  
Katsuaki Sunakoda ◽  
Kazuhiko Hiramoto ◽  
Issei Yamazaki ◽  
Akira Fukukita ◽  
...  
Keyword(s):  
Vibration Control ◽  
Earthquake Engineering ◽  
Vibration Suppression ◽  
Experimental Testing ◽  
Control Device ◽  
Shaking Table ◽  
Ball Screw ◽  
Scale Model ◽  
Small Scale ◽  
Wide Range

In a previous paper the authors proposed a semi-active vibration control device (VCD) that generates power. The device utilizes a ball screw, and has inertial and damping forces. The damping coefficient is adjusted by altering resistance at the terminal of the power generator. A small-scale VCD was manufactured for experimental testing. Frequency responses of a small-scale spring mass structure were measured in order to confirm the effects of vibration suppression within a wide range of frequencies. In this paper, as the next step, vibration tests using a benchmark structure with an installed VCD that has a 30 kN capacity are carried out at the National Center for Research on Earthquake Engineering (NCREE) in Taiwan. The benchmark structure has three stories with a 3 m height and a mass of 6 tons at each floor level for a total height and weight of 9 m and 18 tons, respectively. The VCDs are installed between adjacent floors with steel chevron braces. A simple control law that is based on a minimized Lyapunov function and employs bang-bang operation is used as a variable current controller instead of the modifying the resistance level of the VCD. Scaled earthquake motions including the Imperial Valley El Centro north-south component that is normalized to be a peak level of 0.5 m/s2, are applied to the base of the steel framed structure in the horizontal direction by a shaking table. Experimental responses of each floor for the uncontrolled and controlled cases are compared with analytical responses, and effects of vibration suppression for the large-scale model are discussed quantitatively.

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