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(1 - 7 of 7)
- Title
- Kinematical Modelling and Its Analytical Inverse Kinematic Solution for the Handling Mechanism of an Agricultural Robot.
- Creator
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Defterli, Sinem, Xu, Yunjun, Lin, Kuo-Chi, Zheng, Qipeng, Song, Sang-Eun, University of Central Florida
- Abstract / Description
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Early detection of the crop diseases helps to prevent failure in the amount and the quality of the production. In agricultural robotics, the idea of a disease detection robot is a fresh and an innovative hot-button topic. The exclusion of the diseased parts from the strawberry plants for further analyses is one of the main tasks of a recently developed strawberry robot. To this purpose, the handling mechanism in the robot needs to achieve an accurate manipulation task to reach the target....
Show moreEarly detection of the crop diseases helps to prevent failure in the amount and the quality of the production. In agricultural robotics, the idea of a disease detection robot is a fresh and an innovative hot-button topic. The exclusion of the diseased parts from the strawberry plants for further analyses is one of the main tasks of a recently developed strawberry robot. To this purpose, the handling mechanism in the robot needs to achieve an accurate manipulation task to reach the target. Reaching, cutting and storing the diseased leaf are challenging and delicate processes during the procedure of the handling mechanism operation in the field.The manipulation task of the mechanism is succeeded when the inverse kinematic relations from workspace to joint space are defined properly. The inverse kinematic analysis is usually subjected to the restrictions due to the limitations in mechanical design of the mechanism, hardware components and operation environment of the robots as well as the morphology of the target. This study proposes a set of analytical algorithms to solve the inverse kinematics problem of the handling mechanism under certain constraints. First, proposed analytical approach is based on the calculation of the joint variables by solving only the 3D position information of the target since the output from image processing algorithms of vision subsystem in the ground robot is only the location of the diseased point. The position of target point is the only output from vision subsystem and this data will be given as an input to the proposed algorithms. Second, the mechanism has certain restrictions on its geometrical construction and the joint actuators' capacity. Hence, these restrictions limit the range of joint variables to be solved. Due to sudden and unpredicted nature of field conditions, the quickness of handling mechanism inverse kinematics solution's execution has a vital effect on the success of the picking task of the robot. Another essential factor is to use the battery life of the robot effectively, by minimizing energy consumption. Therefore, the effectiveness of the proposed algorithm is decided by comparing the developed performance indices of consumed energy and CPU time cost via numerical solution namely, a nonlinear constrained optimization method under same restrictions of inverse kinematics problem. Performance of both algorithms is observed by the simulations in MATLAB(&)#174; and laboratory set-up experiments.
Show less - Date Issued
- 2016
- Identifier
- CFE0006291, ucf:51588
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006291
- Title
- THE RISKS AND BENEFITS OF RUNNING BAREFOOT OR IN MINIMALIST SHOES: A SYSTEMATIC REVIEW.
- Creator
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Perkins, Kyle, Rothschild, Carey, University of Central Florida
- Abstract / Description
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The popularity of running barefoot or in minimalist shoes has notably increased in the last decade due to claims of injury prevention, enhanced running efficiency, and improved performance when compared to running in shoes (shod). A systematic review of the literature was performed using the Downs and Black checklist to assess the methodological quality of studies proposing risks or benefits between running barefoot, shod, or in minimalist shoes. The databases Ovid MEDLINE, SPORTDiscus, and...
Show moreThe popularity of running barefoot or in minimalist shoes has notably increased in the last decade due to claims of injury prevention, enhanced running efficiency, and improved performance when compared to running in shoes (shod). A systematic review of the literature was performed using the Downs and Black checklist to assess the methodological quality of studies proposing risks or benefits between running barefoot, shod, or in minimalist shoes. The databases Ovid MEDLINE, SPORTDiscus, and CINAHL were searched using keywords or "Booleans" including: "Barefoot", "Running" and "Minimalist," exclusively. All included articles were obtained from peer reviewed journals in the English language with a link to full text and no limit for year of publication. The final selection was made based on inclusion of at least one of the following outcome variables: pain, injury rate, running economy, joint forces, running velocity, electromyography, muscle performance, or edema. Significant results were gathered from identified articles and compared using "Levels of Evidence" by Furlan et al. Twenty-three publications were identified and rated for quality assessment in September 2013. Out of 27 possible points on the Downs and Black checklist, all articles scored between 13 and 19 points with a mean of 17.4. Evidence from the articles ranged from very limited to moderate. Moderate evidence suggested overall less maximum vertical ground reaction forces, less extension moment and power absorption at the knee, less foot and ankle dorsiflexion at ground contact, less ground contact time, shorter stride length, increased stride frequency (cadence), as well as increased knee flexion at ground contact in barefoot running compared to shod. The low scores from the quality assessment using the Downs and Black checklist indicates that improved methodological quality is necessary to provide strong evidence comparing the risks and benefits of running barefoot, shod, and in minimalist shoes. The literature between shod, minimalist, and barefoot running is inconclusive. There is limited evidence showing differences in kinematics, kinetics, electromyography, and economy results in minimalist shoes. Thus, an alternative and suitable method to effectively replicate barefoot running has not yet been determined.
Show less - Date Issued
- 2013
- Identifier
- CFH0004532, ucf:45194
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004532
- Title
- IS PERCEIVED INTENTIONALITY OF A VIRTUAL ROBOT INFLUENCED BY THE KINEMATICS?.
- Creator
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Sasser, Jordan, McConnell, Daniel S., University of Central Florida
- Abstract / Description
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Research has shown that in Human-Human Interactions kinematic information reveals that competitive and cooperative intentions are perceivable and suggests the existence of a cooperation bias. The present study invokes the same question in a Human-Robot Interaction by investigating the relationship between the acceleration of a virtual robot within a virtual reality environment and the participants perception of the situation being cooperative or competitive by attempting to identify the...
Show moreResearch has shown that in Human-Human Interactions kinematic information reveals that competitive and cooperative intentions are perceivable and suggests the existence of a cooperation bias. The present study invokes the same question in a Human-Robot Interaction by investigating the relationship between the acceleration of a virtual robot within a virtual reality environment and the participants perception of the situation being cooperative or competitive by attempting to identify the social cues used for those perceptions. Five trials, which are mirrored, faster acceleration, slower acceleration, varied acceleration with a loss, and varied acceleration with a win, were experienced by the participant; randomized within two groups of five totaling in ten events. Results suggest that when the virtual robot's acceleration pattern were faster than the participant's acceleration the situation was perceived as more competitive. Additionally, results suggest that while the slower acceleration was perceived as more cooperative, the condition was not significantly different from mirrored acceleration. These results may indicate that there may be some kinematic information found in the faster accelerations that invoke stronger competitive perceptions whereas slower accelerations and mirrored acceleration may blend together during perception; furthermore, the models used in the slower acceleration conditions and the mirrored acceleration provide no single identifiable contributor towards perceived cooperativeness possibly due to a similar cooperative bias. These findings are used as a baseline for understanding movements that can be utilized in the design of better social robotic movements. These movements would improve the interactions between humans and these robots, ultimately improving the robot's ability to help during situations.
Show less - Date Issued
- 2019
- Identifier
- CFH2000524, ucf:45668
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000524
- Title
- THE ROLE OF CUES AND KINEMATICS ON SOCIAL EVENT PERCEPTION.
- Creator
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Berrios, Estefania, McConnell, Daniel S., University of Central Florida
- Abstract / Description
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The belief that intentions are hidden away in the minds of individuals has been circulating for many years. Theories of indirect perception, such as the Theory of Mind, have since been developed to help explain this phenomenon. Conversely, research in the field of human kinematics and event perception have also given rise to theories of direct perception. The purpose of the study was to determine if intentionality can be directly perceived rather than requiring inferential processes. Prior...
Show moreThe belief that intentions are hidden away in the minds of individuals has been circulating for many years. Theories of indirect perception, such as the Theory of Mind, have since been developed to help explain this phenomenon. Conversely, research in the field of human kinematics and event perception have also given rise to theories of direct perception. The purpose of the study was to determine if intentionality can be directly perceived rather than requiring inferential processes. Prior research regarding kinematics of cooperative and competitive movements have pointed toward direct perception, demonstrating participants can accurately judge a movement as cooperative or competitive by simply observing point-light displays of the isolated arm movements. Considering competitive movements are often performed faster than cooperative movements, speed was perturbed for the purpose of this study to determine if participants are relying on cues or if they can indeed perceive a unique kinematic pattern that corresponds to intentionality. Judging the clips correctly despite perturbation would suggest perception is direct. Additionally, we hypothesized judgments accuracy would be higher in the presence of two actors pointing to the use of interpersonal affordances. Twenty-eight participants from the University of Central Florida were asked to judge 40 clips presented in random order including: normal or perturbed competitive actions with one or two actors; normal or perturbed cooperative actions with one or two actors. Percent correct and reaction time data were analyzed on SPSS using a repeated measures ANOVA. Results rejected the hypothesis that social perception is direct and supported indirect perception, indicating participants relied on cues to make judgments, and provided potential support for the interpersonal affordance hypothesis.
Show less - Date Issued
- 2019
- Identifier
- CFH2000514, ucf:45681
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000514
- Title
- Application of Multiaxial Cyclic Loading for Constitutive Model and Parameter Determination of Steels.
- Creator
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Felemban, Bassem, Gordon, Ali, Moslehy, Faissal, Bai, Yuanli, Nam, Boo Hyun, University of Central Florida
- Abstract / Description
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For many candidate materials, constitutive models and their parameters are identified using uniaxial test data. Real components, however, generally operate in a multi-axial loading environments. Consequently, constitutive models deployed by uniaxial conditions may carry over to service conditions with inherit limitations. Research is proposed to determine the constitutive model constants for the creep and plasticity responses of a material via multi-axial fatigue testing which may contain...
Show moreFor many candidate materials, constitutive models and their parameters are identified using uniaxial test data. Real components, however, generally operate in a multi-axial loading environments. Consequently, constitutive models deployed by uniaxial conditions may carry over to service conditions with inherit limitations. Research is proposed to determine the constitutive model constants for the creep and plasticity responses of a material via multi-axial fatigue testing which may contain ratcheting. It is conjectured that directly regressing data under conditions that favor those of actual service use will lead to more accurate modeling under these conditions, as well as a reduced consumption of model development resources. Application of observations of multiaxial loading in the determination of constitutive modeling constants and model selection represents a paradigm shift for material characterization. Numerical simulation and experimentation are necessary for material selection for application at high temperature. The candidate material used in this study is primarily applied for structural components in high-temperature environments for steam generating systems (-) 304 stainless steel. It confers an excellent balance of ductility, corrosion resistance, and creep resistance at moderate temperatures (i.e., up to 550?C). Under service conditions, both creep and cyclic plasticity can occur under either isothermal or non-isothermal conditions. Accurate deformation modeling and life prediction of these structures only achieved with an accurate understanding of how this and other key alloys behave under complex conditions. This research conveys a proposed methodology that can be used to apply creep and plasticity constitutive models that correlate with experimental data. Several creep and plasticity models are examined to augment the accuracy of the models. These results are presented to illustrate modeling performance. Based on this idea has been determined that novel methods of measuring the accuracy of modeling be needed, as well as methods for optimizing material response under multiaxial conditions. The models are applied under service-like conditions to gain an understanding of how this and other key alloys behave under complex conditions. This research will study the complex tensile-torsion loading to determine the constitutive constants for material, and thus will decrease the number of uniaxial experiments. Additionally, combined analytical and experimental methods will be used to establish the Bree diagram for elevated temperature tensile-torsion responses. This deformation mechanism map has been useful as a design tool for materials undergoing ratcheting.
Show less - Date Issued
- 2017
- Identifier
- CFE0006875, ucf:51760
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006875
- Title
- Study On Anisotropic Plasticity And Fracture Of Lightweight Metal Sheets.
- Creator
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Jia, Yueqian, Bai, Yuanli, Kassab, Alain, Raghavan, Seetha, Gou, Jihua, Wu, Thomas, University of Central Florida
- Abstract / Description
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How to reduce weight and increase fuel efficiency is a critical challenge in transportation industries. One way to resolve the problem is to adopting lightweight alloys (i.e. advanced high strength steel, aluminum alloys, or magnesium alloy) in structure designs and manufacturing. Fully understanding the mechanical properties of these materials is a key step.In order to fully characterize the plasticity and fracture of magnesium AZ31B-H24 sheets, a set of mechanical experiments (170 in total)...
Show moreHow to reduce weight and increase fuel efficiency is a critical challenge in transportation industries. One way to resolve the problem is to adopting lightweight alloys (i.e. advanced high strength steel, aluminum alloys, or magnesium alloy) in structure designs and manufacturing. Fully understanding the mechanical properties of these materials is a key step.In order to fully characterize the plasticity and fracture of magnesium AZ31B-H24 sheets, a set of mechanical experiments (170 in total) were performed under both monotonic and non-proportional loading conditions, including monotonic uniaxial tension, notch tension, in-plane uniaxial compression, wide compression (or called biaxial compression), plane strain compression, through-thickness compression, in-plane shear, punch test, uniaxial compression-tension reverse loading, and two-step uniaxial tension (cross-loading).Both the plastic strain histories and stress responses were obtained under the above loading conditions, which give a comprehensive picture of mechanical behaviors of this material. No apparent cross-hardening effect was observed for this material.An extended orthotropic yield criterion involving two linear anisotropic transformation tensors, CPB06ex2, in conjunction with its associated flow rule was fully calibrated to describe both the anisotropy in plastic flow and tension-compression asymmetry in stress-strain behaviors.A fully modularized framework to combine isotropic, kinematic, and cross hardening behaviors was established under non-monotonic loading conditions. Three sets of state variables were defined and applied to consider the effects of, a) loading history, b) twinning and de-twinning and c) different pre-strain.In order to predict ductile fracture of metal sheets, the (")mixed(") stress/strain invariants based Modified-Mohr-Coulomb (MMC) fracture model was transferred into an all-strain based MMC (eMMC) model under plane stress condition, predicting the fracture strain dependent on strain ratio or ? angle, instead of stress triaxiality and Lode angle parameter. The strain ratio or ? angle could be directly measured by digital image correlation (DIC), while the latter required finite element analysis to be determined. This method makes it possible to study material fracture behavior while bypassing plasticity. The eMMC fracture locus can be fully calibrated by fracture strains directly measured from DIC. The fracture strain was also extended by a linear transformation operating to the plastic strain tensor to incorporate the fracture anisotropy. All models were implemented into Abaqus/Explicit as a user material subroutine (VUMAT). Good prediction capability has been demonstrated for magnesium AZ31B-H24 sheets by FE simulation using shell elements.The current framework was also applied for TRIP780, BH240, DP600, and EDDQ steel sheets with adjustment, under different loading conditions. The FE simulation results for TRIP780 correlated well with experimental data under different monotonic loading conditions. The analytical results for BH240, DP600, and EDDQ demonstrated good prediction capability for cross-hardening behavior, and validated by the non-proportional experimental data under two-stage uniaxial tension.
Show less - Date Issued
- 2016
- Identifier
- CFE0006121, ucf:51165
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006121
- Title
- Characterization of Anisotropic Mechanical Performance of As-Built Additively Manufactured Metals.
- Creator
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Siddiqui, Sanna, Gordon, Ali, Raghavan, Seetha, Bai, Yuanli, Sohn, Yongho, University of Central Florida
- Abstract / Description
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Additive manufacturing (AM) technologies use a 3D Computer Aided Design (CAD) model to develop a component through a deposition and fusion layer process, allowing for rapid design and geometric flexibility of metal components, for use in the aerospace, energy and biomedical industries. Challenges exist with additive manufacturing that limits its replacement of conventional manufacturing techniques, most especially a comprehensive understanding of the anisotropic behavior of these materials...
Show moreAdditive manufacturing (AM) technologies use a 3D Computer Aided Design (CAD) model to develop a component through a deposition and fusion layer process, allowing for rapid design and geometric flexibility of metal components, for use in the aerospace, energy and biomedical industries. Challenges exist with additive manufacturing that limits its replacement of conventional manufacturing techniques, most especially a comprehensive understanding of the anisotropic behavior of these materials and how it is reflected in observed tensile, torsional and fatigue mechanical responses. As such, there is a need to understand how the build orientation of as-built additively manufactured metals, affects mechanical performance (e.g. monotonic and cyclic behavior, cyclically hardening/softening behavior, plasticity effects on fatigue life etc.); and to use constitutive modeling to both support experimental findings, and provide approximations of expected behavior (e.g. failure surfaces, monotonic and cyclic response, correlations between tensile and fatigue properties), for orientations and experiments not tested, due to the expensive cost associated with AM. A comprehensive framework has been developed to characterize the anisotropic behavior of as-built additively manufactured metals (i.e. Stainless Steel GP1 (SS GP1), similar in chemical composition to Stainless Steel 17-4PH), through a series of mechanical testing, microscopic evaluation and constitutive modeling, which were used to identify a reduced specimen size for characterizing these materials. An analysis of the torsional response of additively manufactured Inconel 718 has been performed to assess the impact of build orientation and as-built conditions on the shearing behavior of this material. Experimental results from DMLS SS GP1 and AM Inconel 718 from literature were used to constitutively model the material responses of these additively manufactured metals. Overall, this framework has been designed to serve as standard, from which build orientation selection can be used to meet specific desired industry requirements.
Show less - Date Issued
- 2018
- Identifier
- CFE0007097, ucf:52883
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007097
