This final report documents the Advanced Highway Maintenance and Construction Technology (AHMCT) ... more This final report documents the Advanced Highway Maintenance and Construction Technology (AHMCT) Research Center's Phase Two development of the Advanced Snowplow (ASP), titled "Development of an Advanced Snowplow Driver Assistance System (ASP-II)." This work applies Intelligent Vehicle (IV) and Advanced Vehicle Control and Safety Systems (AVCSS) technologies to enhance the safety and efficiency of snow removal. The system developed includes lane position indication and lane departure warning, as well as a forward collision warning system. The technology has been integrated onto a Caltrans 10-wheel 10-yard plow, and tested through the Winter of 1999-2000 in the California Advanced Winter Maintenance Testbed on Interstate 80 near Donner Summit. The system was also tested for three weeks at a similar site on US 180 near Flagstaff, Arizona. The report provides motivation including a brief history of the previous phase (ASP-I), system overview, major subsystems, and functions. It also describes the Human-Machine Interface (HMI), the magnetic sensing system, and the radar-based Collision Warning System (CWS) in detail. The report also discusses improvements made based on findings from the Phase I research, as well as evaluation, conclusions, and future research.
2017 9th International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), 2017
Quantitative ranking between alternatives and the selection of the most promising one is highly c... more Quantitative ranking between alternatives and the selection of the most promising one is highly challenging. Typically, multiple criteria need to be granted and weighed based on task and user requirements. It is getting more complicated with increasing numbers of requirements and stakeholders now common in feature-rich control systems. Hence, there is a need for a systematic method of dealing with Multi-Criteria-Decision-Making (MCDM) problems. In this paper, we develop a systematic approach by integrating the House-of-Quality (HoQ) method with Multi-Attribute-Utility-Theory (MAUT). It is shown that combining HoQ and MAUT allows the integration of different task and user requirements. This method is used to perform criteria comparisons, which results neither in an overestimation nor an underestimation of the criterion's influence and consequently provides more accurate and predictable results. The methods are applied to the evaluation of three different collaborative software en...
In this paper we present a method for dynamically interpolating the motion of a rigid body in spa... more In this paper we present a method for dynamically interpolating the motion of a rigid body in space between known end-positions. We begin by creating an image space representation of the equations of motion for a rigid body. These equations are written as a system of first-order state equations whose trajectory is optimized based on the minimization of a certain performance index. This leads to a set of boundary-value equations between the end positions, which when solved give the interpolated motion. Finally, a program developed to perform such interpolations numerically is utilized by generating a trajectory between given terminal states.
Rural transportation districts in California cannot easily justify the one-time and recurring cos... more Rural transportation districts in California cannot easily justify the one-time and recurring costs of an urban ATMS (advanced traffic management system). A low-cost alternative would provide significant operational capabilities to the districts, with substantial savings to the California Department of Transportation (Caltrans). The open-source Intelligent Roadway Information System (IRIS), developed by the Minnesota Department of Transportation, was customized by the Advanced Highway Maintenance and Construction Technology Research Center at the University of California, Davis. AHMCT provided IRIS testing and technical support to assess its feasibility. Test results and implementation are described. IRIS is currently deployed in District 10, and near deployment in Districts 1, 2, and 5.
This document describes Task 3, “Review of Caltrans District 10 Transportation Management Center ... more This document describes Task 3, “Review of Caltrans District 10 Transportation Management Center Operations and Equipment,” within the Open ATMS multi-year research project undertaken by the Advanced Highway Maintenance & Construction Technology (AHMCT) Research Center at the University of California, Davis. The Open ATMS project is implementing an open-source Advanced Traffic/Transportation Management System (ATMS) within the California State Department of Transportation (Caltrans) District 10 (D10) Transportation Management Center (TMC). This document is a review of Caltrans D10 TMC operations and equipment. This includes D10 TMC software, hardware, communications, and operations. iii Copyright 2011, AHMCT Research Center, UC Davis Review of Caltrans District 10 TMC Operations and Equipment iv Copyright 2011, AHMCT Research Center, UC Davis
This research developed a methodology to compute the life cycle cost of attenuators at the time o... more This research developed a methodology to compute the life cycle cost of attenuators at the time of their selection. It identified the two most important site attributes influencing life cycle costs as being the expected impact frequency and the access factor. Based on the developed methodology, expected site specific cost savings are specified.
PDFTech ReportCA16-1846IA65A0416, Task 1846Incident managementEmergency communication systemsEmer... more PDFTech ReportCA16-1846IA65A0416, Task 1846Incident managementEmergency communication systemsEmergency medical servicesEmergency road serviceEmergency managementFirefightersMedical personnelPolice operationsFirst responseHighway maintenanceemergency responsefirst responderincident managementCaliforniaUnited StatesCalifornia. Dept. of TransportationDonecker, Stephen M.Swanston, TravisYen, KinRavani, BahramLasky, Ty A.University of California, Davis. Dept. of Mechanical and Aeronautical Engineering. AHMCT CenterCalifornia. Dept. of TransportationUS Transportation CollectionThis report documents the research project \u201cDevelopment and Testing of Responder Phase III.\u201d Under previous research, a Responder system has been developed to provide relevant and timely information to first responders, allow responders to provide information on the scene and incident to others in the organization, and support reliable and always available communications. The primary goal of the current project was to migrate the Responder system to the latest computing and communications technologies, including smartphone and tablet systems. The project includes review of previous phase efforts, updating of requirements, review of commercial systems, design and development of Phase III Responder system, and testing and reporting. The research product will provide Caltrans with a more field-ready system to support first responders in rural environments
Journal of Transportation Engineering, Part A: Systems, 2021
AbstractWrong-Way Driving (WWD) crashes have higher fatality rate than other crashes. In contrast... more AbstractWrong-Way Driving (WWD) crashes have higher fatality rate than other crashes. In contrast to much of the existing literature, which has focused on collision data available after a WWD crash...
This paper presents a computational geometric solution to the kinematic registration problem usin... more This paper presents a computational geometric solution to the kinematic registration problem using computational line geometry. Kinematic registration involves computation of the screw parameters of a motion from specified positions of geometric features of the moving body. The problem is formulated using a special complex of lines associated with kinematics namely the bisecting linear line complex. In this fashion the problem is reduced to an approximation problem in the line space and a slightly modified version of the line approximation method developed by Pottmann, Peternell, and Ravani (1999) is used to find the solution.
Additive manufacturing (AM) is suitable for designing and producing complex components that are d... more Additive manufacturing (AM) is suitable for designing and producing complex components that are difficult or impossible to manufacture with conventional manufacturing processes. To ensure the design benefits of AM, novel design approaches such as structural topology optimization and cellular structure design are widely used and bring up the research domain of design for AM (DfAM). However, conventional DfAM approaches mainly focus on the geometry and manufacturability of AM components and rarely consider energy performance as an improvement objective. Given that the energy consumption in AM processes can be a great contributor to the overall environmental impact in the production stage with AM, the evaluation and improvement of the energy performance of AM should be considered in the DfAM approaches; otherwise, opportunities to improve the energy performance by changing product features are missed. To address this research question, we are proposing a framework that enables the evaluation and improvement of the energy performance of AM in the design stage resulting in a new method for DfAM. To validate the framework, two use cases are presented to illustrate the feasibility of developed methods and tools.
The generation of an optimized factory layout is a central element of the factory planning proces... more The generation of an optimized factory layout is a central element of the factory planning process. The generated factory layout predefines multiple characteristics of the future factory, such as the operational costs and proper resource allocations. However, manual layout planning is often time and resource-consuming and involves creative processes. In order to reduce the manual planning effort, automated, computer-aided planning approaches can support the factory planner to deal with this complexity by generating valuable solutions in the early phase of factory layout planning. Novel approaches have introduced Reinforcement Learning based planning schemes to generate optimized factory layouts. However, the existing research mainly focuses on the technical feasibility and does not highlight how a Reinforcement Learning based planning approach can be integrated into the factory planning process. Furthermore, it is unclear which information is required for its application. This paper addresses this research gap by presenting a holistic framework for Reinforcement Learning based factory layout planning that can be applied at the initial planning (greenfield planning) stages as well as in the restructuring (brownfield planning) of a factory layout. The framework consists of five steps: the initialization of the layout planning problem, the initialization of the algorithm, the execution of multiple training sets, the evaluation of the training results, and a final manual planning step for a selected layout variant. Each step consists of multiple sub-steps that are interlinked by an information flow. The framework describes the necessary and optional information for each sub-step and further provides guidance for future developments.
The cellular network standard 5G meets the networking requirements for different industrial use c... more The cellular network standard 5G meets the networking requirements for different industrial use cases due to the advantages of low latency, high bandwidth, and high device density while providing a very good quality of service. These capabilities enable the realization of wireless digital twins (DTs), a key element of future cyber-physical production systems. DTs for prediction, monitoring, and control of machine tools need physical modeling as well as the bidirectional exchange of information between the digital and the physical world. 5G is a wireless communication technology with the potential to disruptively change industrial communication. 5G enables wireless, highly scalable, and flexible realization of even safety-and latency-critical connections. In this paper, a 5G enabled DT of a machine tool for process control, monitoring and simulation is developed and implemented. A bidirectional communication between the physical machine tool and the DT is realized via 5G. Moreover, process prediction is enabled based on physics simulation. Next to the physical modeling of the machine behavior, a 5G-capable interface between the input and output signals of the machine control system and the developed DT is implemented. Moreover, the DT is migrated in a wireless form to an edge server. Furthermore, the capabilities of the DT are demonstrated. Therefore, the architecture and implementation of the DT as well as its benefits and challenges are outlined. 1 Motivation Modern manufacturing systems that incorporate digital technologies-the so-called cyber-physical production systems (CPPS)-seek to interconnect the digital and real world. For better flexibility, scalability, and reconfigurability, CPPS aim to connect individual cyber-physical systems and soften the hierarchical automation pyramid to decentralized distribution of computing units [1]. Due to increased demand for customized products, the requirements on the connectivity, functionality, flexibility, and intelligence of machine tools are also increasing [2]. Consequently, CPPS lead to complex manufacturing systems that are increasingly challenging to control and understand, due to many different decentralized, connected systems (e.g., machine tools, automated guided vehicles, human-machine-interfaces, etc.) with different characteristics, functionalities, and thus different heterogenous information technologies [3].
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
California. Dept. of Transportation. Division of Research and Innovation, Feb 28, 2020
Virtual Design Construction (VDC) and Civil Integrated Management (CIM) are recent innovations th... more Virtual Design Construction (VDC) and Civil Integrated Management (CIM) are recent innovations that have been shown to improve project delivery and reduce cost through the entire lifecycle of a project. Integrating VDC/CIM within the organization's delivery processes would lead to increased efficiencies for tax dollars, cost savings, reduce construction conflicts, decrease construction time, and enhanced workers' and public safety. This research has evaluated the current state of VDC/CIM within Caltrans and collected the known VDC/CIM best practices through literature review of existing public information. In addition, this research has also created a strategic high-level roadmap that identifies the gaps and provides guidance on bridging the gap between the current and future state of VDC/CIM at Caltrans. In order to develop an organic structure within Caltrans for VDC/CIM implementation, formation of organizational level task forces is recommended. The task forces can then work with groups in charge of each Activity area and assist in guiding them through closing the gaps identified in this report and in pushing towards digital transformation.
Exceeding the speed limit in highway work zones is a safety problem for highway workers and the t... more Exceeding the speed limit in highway work zones is a safety problem for highway workers and the traveling public. Adherence to the posted speed limits can provide safety benefits by reducing the number of accidents and the potential casualties and injuries resulting from those accidents. Some states have enacted laws and have adopted the use of automated Photo Speed Enforcement for highway work zones. This research was intended to evaluate existing practices and available technologies and perform testing to establish guidelines and recommendations for the equipment and the configuration for its deployment in California highway work zones. The main research question addressed in this research is the following: Can PSE technology be configured for implementation in highway work zones in California such that it be an effective deterrent to speeding, resulting in improving work zone safety for highway workers and the traveling public? In this research, testing was performed both in a co...
This report documents work performed by the University of California at Davis in collaboration wi... more This report documents work performed by the University of California at Davis in collaboration with the California Department of Transportation (Caltrans) in relationship to a Precursor System Analysis dealing with a study of automated construction, maintenance, and operational requirements for Automated Highway Systems (AHS). This study was conducted in the activity area "K" dealing with AHS roadway operational analysis. The report documents a design analysis for a robotic system for automated installation of discrete magnetic markers for AHS. The design includes a manpower assessment and a cost-benefit analysis. Summaries for supporting research are included in appendices, including: a literature review, a reference architecture and classification system for AHS, and a computer simulation and animation of the prototype discrete magnetic marker placement system described in this report.
Page 1. Design and Mechatronic Implementation of an Accelerometer-Based, Kinematically Redundant ... more Page 1. Design and Mechatronic Implementation of an Accelerometer-Based, Kinematically Redundant Inertial Measurement Unit Kourosh Parsa, Ty A. Lasky, and Bahram Ravani Abstract ... indeterminate. Parsa et al [8] determined the ...
In this paper, we present a differential-geometric approach to analyze the singularities of task ... more In this paper, we present a differential-geometric approach to analyze the singularities of task space point trajectories of two and three-degree-of-freedom serial and parallel manipulators. At non-singular configurations, the first-order, local properties are characterized by metric coefficients, and, geometrically, by the shape and size of a velocity ellipse or an ellipsoid. At singular configurations, the determinant of the matrix of metric coefficients is zero and the velocity ellipsoid degenerates to an ellipse, a line or a point, and the area or the volume of the velocity ellipse or ellipsoid becomes zero. The degeneracies of the velocity ellipsoid or ellipse gives a simple geometric picture of the possible task space velocities at a singular configuration. To study the second-order properties at a singularity, we use the derivatives of the metric coefficients and the rate of change of area or volume. The derivatives are shown to be related to the possible task space accelerations at a singular configuration. In the case of parallel manipulators, singularities may lead to either loss or gain of one or more degrees-of-freedom. For loss of one or more degrees-of-freedom, the possible velocities and accelerations are again obtained from a modified metric and derivatives of the metric coefficients. In the case of a gain of one or more degrees-of-freedom, the possible task space velocities can be pictured as growth to lines, ellipses, and ellipsoids. The theoretical results are illustrated with the help of a general spatial 2R manipulator and a three-degree-of-freedom RPSSPR-SPR parallel manipulator.
This final report documents the Advanced Highway Maintenance and Construction Technology (AHMCT) ... more This final report documents the Advanced Highway Maintenance and Construction Technology (AHMCT) Research Center's Phase Two development of the Advanced Snowplow (ASP), titled "Development of an Advanced Snowplow Driver Assistance System (ASP-II)." This work applies Intelligent Vehicle (IV) and Advanced Vehicle Control and Safety Systems (AVCSS) technologies to enhance the safety and efficiency of snow removal. The system developed includes lane position indication and lane departure warning, as well as a forward collision warning system. The technology has been integrated onto a Caltrans 10-wheel 10-yard plow, and tested through the Winter of 1999-2000 in the California Advanced Winter Maintenance Testbed on Interstate 80 near Donner Summit. The system was also tested for three weeks at a similar site on US 180 near Flagstaff, Arizona. The report provides motivation including a brief history of the previous phase (ASP-I), system overview, major subsystems, and functions. It also describes the Human-Machine Interface (HMI), the magnetic sensing system, and the radar-based Collision Warning System (CWS) in detail. The report also discusses improvements made based on findings from the Phase I research, as well as evaluation, conclusions, and future research.
2017 9th International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), 2017
Quantitative ranking between alternatives and the selection of the most promising one is highly c... more Quantitative ranking between alternatives and the selection of the most promising one is highly challenging. Typically, multiple criteria need to be granted and weighed based on task and user requirements. It is getting more complicated with increasing numbers of requirements and stakeholders now common in feature-rich control systems. Hence, there is a need for a systematic method of dealing with Multi-Criteria-Decision-Making (MCDM) problems. In this paper, we develop a systematic approach by integrating the House-of-Quality (HoQ) method with Multi-Attribute-Utility-Theory (MAUT). It is shown that combining HoQ and MAUT allows the integration of different task and user requirements. This method is used to perform criteria comparisons, which results neither in an overestimation nor an underestimation of the criterion's influence and consequently provides more accurate and predictable results. The methods are applied to the evaluation of three different collaborative software en...
In this paper we present a method for dynamically interpolating the motion of a rigid body in spa... more In this paper we present a method for dynamically interpolating the motion of a rigid body in space between known end-positions. We begin by creating an image space representation of the equations of motion for a rigid body. These equations are written as a system of first-order state equations whose trajectory is optimized based on the minimization of a certain performance index. This leads to a set of boundary-value equations between the end positions, which when solved give the interpolated motion. Finally, a program developed to perform such interpolations numerically is utilized by generating a trajectory between given terminal states.
Rural transportation districts in California cannot easily justify the one-time and recurring cos... more Rural transportation districts in California cannot easily justify the one-time and recurring costs of an urban ATMS (advanced traffic management system). A low-cost alternative would provide significant operational capabilities to the districts, with substantial savings to the California Department of Transportation (Caltrans). The open-source Intelligent Roadway Information System (IRIS), developed by the Minnesota Department of Transportation, was customized by the Advanced Highway Maintenance and Construction Technology Research Center at the University of California, Davis. AHMCT provided IRIS testing and technical support to assess its feasibility. Test results and implementation are described. IRIS is currently deployed in District 10, and near deployment in Districts 1, 2, and 5.
This document describes Task 3, “Review of Caltrans District 10 Transportation Management Center ... more This document describes Task 3, “Review of Caltrans District 10 Transportation Management Center Operations and Equipment,” within the Open ATMS multi-year research project undertaken by the Advanced Highway Maintenance & Construction Technology (AHMCT) Research Center at the University of California, Davis. The Open ATMS project is implementing an open-source Advanced Traffic/Transportation Management System (ATMS) within the California State Department of Transportation (Caltrans) District 10 (D10) Transportation Management Center (TMC). This document is a review of Caltrans D10 TMC operations and equipment. This includes D10 TMC software, hardware, communications, and operations. iii Copyright 2011, AHMCT Research Center, UC Davis Review of Caltrans District 10 TMC Operations and Equipment iv Copyright 2011, AHMCT Research Center, UC Davis
This research developed a methodology to compute the life cycle cost of attenuators at the time o... more This research developed a methodology to compute the life cycle cost of attenuators at the time of their selection. It identified the two most important site attributes influencing life cycle costs as being the expected impact frequency and the access factor. Based on the developed methodology, expected site specific cost savings are specified.
PDFTech ReportCA16-1846IA65A0416, Task 1846Incident managementEmergency communication systemsEmer... more PDFTech ReportCA16-1846IA65A0416, Task 1846Incident managementEmergency communication systemsEmergency medical servicesEmergency road serviceEmergency managementFirefightersMedical personnelPolice operationsFirst responseHighway maintenanceemergency responsefirst responderincident managementCaliforniaUnited StatesCalifornia. Dept. of TransportationDonecker, Stephen M.Swanston, TravisYen, KinRavani, BahramLasky, Ty A.University of California, Davis. Dept. of Mechanical and Aeronautical Engineering. AHMCT CenterCalifornia. Dept. of TransportationUS Transportation CollectionThis report documents the research project \u201cDevelopment and Testing of Responder Phase III.\u201d Under previous research, a Responder system has been developed to provide relevant and timely information to first responders, allow responders to provide information on the scene and incident to others in the organization, and support reliable and always available communications. The primary goal of the current project was to migrate the Responder system to the latest computing and communications technologies, including smartphone and tablet systems. The project includes review of previous phase efforts, updating of requirements, review of commercial systems, design and development of Phase III Responder system, and testing and reporting. The research product will provide Caltrans with a more field-ready system to support first responders in rural environments
Journal of Transportation Engineering, Part A: Systems, 2021
AbstractWrong-Way Driving (WWD) crashes have higher fatality rate than other crashes. In contrast... more AbstractWrong-Way Driving (WWD) crashes have higher fatality rate than other crashes. In contrast to much of the existing literature, which has focused on collision data available after a WWD crash...
This paper presents a computational geometric solution to the kinematic registration problem usin... more This paper presents a computational geometric solution to the kinematic registration problem using computational line geometry. Kinematic registration involves computation of the screw parameters of a motion from specified positions of geometric features of the moving body. The problem is formulated using a special complex of lines associated with kinematics namely the bisecting linear line complex. In this fashion the problem is reduced to an approximation problem in the line space and a slightly modified version of the line approximation method developed by Pottmann, Peternell, and Ravani (1999) is used to find the solution.
Additive manufacturing (AM) is suitable for designing and producing complex components that are d... more Additive manufacturing (AM) is suitable for designing and producing complex components that are difficult or impossible to manufacture with conventional manufacturing processes. To ensure the design benefits of AM, novel design approaches such as structural topology optimization and cellular structure design are widely used and bring up the research domain of design for AM (DfAM). However, conventional DfAM approaches mainly focus on the geometry and manufacturability of AM components and rarely consider energy performance as an improvement objective. Given that the energy consumption in AM processes can be a great contributor to the overall environmental impact in the production stage with AM, the evaluation and improvement of the energy performance of AM should be considered in the DfAM approaches; otherwise, opportunities to improve the energy performance by changing product features are missed. To address this research question, we are proposing a framework that enables the evaluation and improvement of the energy performance of AM in the design stage resulting in a new method for DfAM. To validate the framework, two use cases are presented to illustrate the feasibility of developed methods and tools.
The generation of an optimized factory layout is a central element of the factory planning proces... more The generation of an optimized factory layout is a central element of the factory planning process. The generated factory layout predefines multiple characteristics of the future factory, such as the operational costs and proper resource allocations. However, manual layout planning is often time and resource-consuming and involves creative processes. In order to reduce the manual planning effort, automated, computer-aided planning approaches can support the factory planner to deal with this complexity by generating valuable solutions in the early phase of factory layout planning. Novel approaches have introduced Reinforcement Learning based planning schemes to generate optimized factory layouts. However, the existing research mainly focuses on the technical feasibility and does not highlight how a Reinforcement Learning based planning approach can be integrated into the factory planning process. Furthermore, it is unclear which information is required for its application. This paper addresses this research gap by presenting a holistic framework for Reinforcement Learning based factory layout planning that can be applied at the initial planning (greenfield planning) stages as well as in the restructuring (brownfield planning) of a factory layout. The framework consists of five steps: the initialization of the layout planning problem, the initialization of the algorithm, the execution of multiple training sets, the evaluation of the training results, and a final manual planning step for a selected layout variant. Each step consists of multiple sub-steps that are interlinked by an information flow. The framework describes the necessary and optional information for each sub-step and further provides guidance for future developments.
The cellular network standard 5G meets the networking requirements for different industrial use c... more The cellular network standard 5G meets the networking requirements for different industrial use cases due to the advantages of low latency, high bandwidth, and high device density while providing a very good quality of service. These capabilities enable the realization of wireless digital twins (DTs), a key element of future cyber-physical production systems. DTs for prediction, monitoring, and control of machine tools need physical modeling as well as the bidirectional exchange of information between the digital and the physical world. 5G is a wireless communication technology with the potential to disruptively change industrial communication. 5G enables wireless, highly scalable, and flexible realization of even safety-and latency-critical connections. In this paper, a 5G enabled DT of a machine tool for process control, monitoring and simulation is developed and implemented. A bidirectional communication between the physical machine tool and the DT is realized via 5G. Moreover, process prediction is enabled based on physics simulation. Next to the physical modeling of the machine behavior, a 5G-capable interface between the input and output signals of the machine control system and the developed DT is implemented. Moreover, the DT is migrated in a wireless form to an edge server. Furthermore, the capabilities of the DT are demonstrated. Therefore, the architecture and implementation of the DT as well as its benefits and challenges are outlined. 1 Motivation Modern manufacturing systems that incorporate digital technologies-the so-called cyber-physical production systems (CPPS)-seek to interconnect the digital and real world. For better flexibility, scalability, and reconfigurability, CPPS aim to connect individual cyber-physical systems and soften the hierarchical automation pyramid to decentralized distribution of computing units [1]. Due to increased demand for customized products, the requirements on the connectivity, functionality, flexibility, and intelligence of machine tools are also increasing [2]. Consequently, CPPS lead to complex manufacturing systems that are increasingly challenging to control and understand, due to many different decentralized, connected systems (e.g., machine tools, automated guided vehicles, human-machine-interfaces, etc.) with different characteristics, functionalities, and thus different heterogenous information technologies [3].
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
California. Dept. of Transportation. Division of Research and Innovation, Feb 28, 2020
Virtual Design Construction (VDC) and Civil Integrated Management (CIM) are recent innovations th... more Virtual Design Construction (VDC) and Civil Integrated Management (CIM) are recent innovations that have been shown to improve project delivery and reduce cost through the entire lifecycle of a project. Integrating VDC/CIM within the organization's delivery processes would lead to increased efficiencies for tax dollars, cost savings, reduce construction conflicts, decrease construction time, and enhanced workers' and public safety. This research has evaluated the current state of VDC/CIM within Caltrans and collected the known VDC/CIM best practices through literature review of existing public information. In addition, this research has also created a strategic high-level roadmap that identifies the gaps and provides guidance on bridging the gap between the current and future state of VDC/CIM at Caltrans. In order to develop an organic structure within Caltrans for VDC/CIM implementation, formation of organizational level task forces is recommended. The task forces can then work with groups in charge of each Activity area and assist in guiding them through closing the gaps identified in this report and in pushing towards digital transformation.
Exceeding the speed limit in highway work zones is a safety problem for highway workers and the t... more Exceeding the speed limit in highway work zones is a safety problem for highway workers and the traveling public. Adherence to the posted speed limits can provide safety benefits by reducing the number of accidents and the potential casualties and injuries resulting from those accidents. Some states have enacted laws and have adopted the use of automated Photo Speed Enforcement for highway work zones. This research was intended to evaluate existing practices and available technologies and perform testing to establish guidelines and recommendations for the equipment and the configuration for its deployment in California highway work zones. The main research question addressed in this research is the following: Can PSE technology be configured for implementation in highway work zones in California such that it be an effective deterrent to speeding, resulting in improving work zone safety for highway workers and the traveling public? In this research, testing was performed both in a co...
This report documents work performed by the University of California at Davis in collaboration wi... more This report documents work performed by the University of California at Davis in collaboration with the California Department of Transportation (Caltrans) in relationship to a Precursor System Analysis dealing with a study of automated construction, maintenance, and operational requirements for Automated Highway Systems (AHS). This study was conducted in the activity area "K" dealing with AHS roadway operational analysis. The report documents a design analysis for a robotic system for automated installation of discrete magnetic markers for AHS. The design includes a manpower assessment and a cost-benefit analysis. Summaries for supporting research are included in appendices, including: a literature review, a reference architecture and classification system for AHS, and a computer simulation and animation of the prototype discrete magnetic marker placement system described in this report.
Page 1. Design and Mechatronic Implementation of an Accelerometer-Based, Kinematically Redundant ... more Page 1. Design and Mechatronic Implementation of an Accelerometer-Based, Kinematically Redundant Inertial Measurement Unit Kourosh Parsa, Ty A. Lasky, and Bahram Ravani Abstract ... indeterminate. Parsa et al [8] determined the ...
In this paper, we present a differential-geometric approach to analyze the singularities of task ... more In this paper, we present a differential-geometric approach to analyze the singularities of task space point trajectories of two and three-degree-of-freedom serial and parallel manipulators. At non-singular configurations, the first-order, local properties are characterized by metric coefficients, and, geometrically, by the shape and size of a velocity ellipse or an ellipsoid. At singular configurations, the determinant of the matrix of metric coefficients is zero and the velocity ellipsoid degenerates to an ellipse, a line or a point, and the area or the volume of the velocity ellipse or ellipsoid becomes zero. The degeneracies of the velocity ellipsoid or ellipse gives a simple geometric picture of the possible task space velocities at a singular configuration. To study the second-order properties at a singularity, we use the derivatives of the metric coefficients and the rate of change of area or volume. The derivatives are shown to be related to the possible task space accelerations at a singular configuration. In the case of parallel manipulators, singularities may lead to either loss or gain of one or more degrees-of-freedom. For loss of one or more degrees-of-freedom, the possible velocities and accelerations are again obtained from a modified metric and derivatives of the metric coefficients. In the case of a gain of one or more degrees-of-freedom, the possible task space velocities can be pictured as growth to lines, ellipses, and ellipsoids. The theoretical results are illustrated with the help of a general spatial 2R manipulator and a three-degree-of-freedom RPSSPR-SPR parallel manipulator.
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Papers by Bahram Ravani