Affecting Fundamental Transformation in Future Construction Work Through Replication of the Master-Apprentice Learning Model in Human-Robot Worker Teams

Construction robots continue to be increasingly deployed on construction sites to assist human workers in various tasks to improve safety, efficiency, and productivity. Due to the recent and ongoing growth in robot capabilities and functionalities, humans and robots are now able to work side-by-side and share workspaces. However, due to inherent safety and trust-related concerns, human-robot collaboration is subject to strict safety standards that require robot motion and forces to be sensitive to proximate human workers. In addition, construction robots are required to perform construction tasks in unstructured and cluttered environments. The tasks are quasi-repetitive, and robots need to handle unexpected circumstances arising from loose tolerances and discrepancies between as-designed and as-built work. It is therefore impractical to pre-program construction robots or apply optimization methods to determine robot motion trajectories for the performance of typical construction work. This research first proposes a new taxonomy for human-robot collaboration on construction sites, which includes five levels: Pre-Programming, Adaptive Manipulation, Imitation Learning, Improvisatory Control, and Full Autonomy, and identifies the gaps existing in knowledge transfer between humans and assisting robots. In an attempt to address the identified gaps, this research focuses on three key studies: enabling construction robots to estimate their pose ubiquitously within the workspace (Pose Estimation), robots learning to perform construction tasks from human workers (Learning from Demonstration), and robots synchronizing their work plans with human collaborators in real-time (Digital Twin). First, this dissertation investigates the use of cameras as a novel sensor system for estimating the pose of large-scale robotic manipulators relative to the job sites. A deep convolutional network human pose estimation algorithm was adapted and fused with sensor-based poses to provide real-time uninterrupted 6-DOF pose estimates of the manipulator’s components. The network was trained with image datasets collected from a robotic excavator in the laboratory and conventional excavators on construction sites. The proposed system yielded an uninterrupted and centimeter-level accuracy pose estimation system for articulated construction robots. Second, this dissertation investigated Robot Learning from Demonstration (LfD) methods to teach robots how to perform quasi-repetitive construction tasks, such as the ceiling tile installation process. LfD methods have the potential to be used in teaching robots specific tasks through human demonstration, such that the robots can then perform the same tasks under different conditions. A visual LfD and a trajectory LfD methods are developed to incorporate the context translation model, Reinforcement Learning method, and generalized cylinders with orientation approach to generate the control policy for the robot to perform the subsequent tasks. The evaluated results in the Gazebo robotics simulator confirm the promise and applicability of the LfD method in teaching robot apprentices to perform quasi-repetitive tasks on construction sites. Third, this dissertation explores a safe working environment for human workers and robots. Robot simulations in online Digital Twins can be used to extend designed construction models, such as BIM (Building Information Models), to the construction phase for real-time monitoring of robot motion planning and control. A bi-directional communication system was developed to bridge robot simulations and physical robots in construction and digital fabrication. Through empirical studies, the high accuracy of the pose synchronization between physical and virtual robots demonstrated the potential for ensuring safety during proximate human-robot co-work.PHDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169666/1/cjliang_1.pd

Towards Smart Earthwork Sites Using Location-based Guidance and Multi-agent Systems

The growing complexity and scope of construction projects is making the coordination and safety of earthwork of a great concern for project and site managers. The difficulty of safeguarding the construction workers is mainly commensurate with the type, scale, and location of the project. In construction operations, where heavy machines are used, various safety and risk issues put the timely completion of a project at stake. Additionally, the construction working environment is heavily susceptible to unforeseen changes and circumstances that could impact the project, both cost and schedule wise. As a response to the looming safety threats or unforeseen changes of working conditions, re-planning is almost always required, in both proactive (preemptive) or reactive (corrective) fashion. In order for re-planning to yield the optimum results, real-time information gathering and processing is a must. Global Positioning System (GPS) and other Real-time Location Systems (RTLSs) have been used for the purpose of real-time data gathering and decision-making in recent years. Similarly, Location-based Guidance Systems (LGSs), e.g., Automated Machine Control/Guidance (AMC/G), have been recently introduced and employed, mainly for the purpose of high-precision earthwork operations. However, currently the application of available LGSs (i.e., AMC/G) is restricted to the machine-level task control and improvement. Also, the high cost of procuring available LGSs, which cost approximately $80,000 for every new piece of equipment, limits the availability of LGSs for small and medium size contractors. Furthermore, the valuable real-time data gathered from various pieces of equipment on site are not effectively utilized to continuously update the simulation models developed at the design phase so that a more realistic view of project progress is available in the execution phase. Finally, despite the growing availability of LGSs, their application for safety is limited to real-time proximity-based object detection and warnings. In view of the ability to control the finest motion of LGS-enabled earthwork equipment, there is a great potential to boost their level of application to the project level, where decisions about the equipment control are made based on the global consideration of a fleet rather that a local view of one single equipment. To the best of the author’s knowledge, a generic methodology that combines real-time data-gathering technologies, LGS and intelligent decision making tools, particularly Multi-agent Systems (MASs), and addresses the safety-sensitive re-planning, is missing. On this premise, this research pursues a methodology which addresses the issue of coordination and safety improvement through the integration of LGSs and MASs. In a nutshell, this research is dedicated to the pursuit of the following objectives: (1) to enable the project-level coordination, monitoring and control through the integration of a MAS architecture and a LGS to help better resolve operational and managerial conflicts; (2) to provide a method for improving the performance of pose estimation based on affordable RTLSs so that LGSs can be applied to a wider scope of older earthwork equipment; (3) to devise a generic framework for Near Real-Time Simulation (NRTS) based on data from LGSs; and (4) to develop a mechanism for improving the safety of earthwork operations using the capabilities of the LGS, NRTS, and MAS. In the proposed framework, every staff member of the project is represented by an exclusive agent in the MASs. More affordable positioning technologies, such as Ultra-Wideband (UWB), are utilized to provide accurate real-time data about the location of machines and workers. An optimization-based method is proposed to consider a set of geometric and operational constraints that govern the behavior of the Data Collectors (DCs) attached to the equipment to improve the equipment pose estimation accuracy. NRTS is used to keep track of the progress of the project and fine-tune the schedule based on the data captured from the site. The agents observe the progress of work executed by their associated equipment, and if any anomalies are detected, viable corrective measures are devised and executed. The inputs to this system are: (a) a stream of real-time data, e.g., location data, flowing from the site, (b) the project design data, and (c) the project progress data and the schedule. Furthermore, a two-layer safety mechanism monitors the safe operation of different pieces of equipment. The first layer of this mechanism enables the equipment to plan a collision-free path considering the predicted movement of all other pieces of equipment. The second layer is acting as a last line of defense in view of possible discrepancies between the predicted paths and actual paths undertaken by the operators. Several prototypes and case studies are developed to demonstrate and verify the feasibility of the proposed framework. It is found that the proposed optimization-based method has a very strong potential to improve the pose estimation using redundancy of more affordable RTLS DCs. Also, the proposed overarching NRTS approach provides a tracking-technology-independent method for processing, analyzing, filtering and visualizing the equipment states that can work with various types of RTLS technologies and under the availability of different levels of sensory data. The proposed safety system is found to provide a balance between economic use of space and the ability to warn against potential collisions in an effective manner using the pose, state, geometry, and speed characteristics of the equipment. Additionally, the safety system demonstrates the ability to provide a reliable basis for the generation of the risk maps of earthwork equipment, using the expected pose and state, and considering the proximity-based and visibility-based risks. The MAS-based framework helps expand the effective domain of LGSs from machine-level guidance to fleet-level coordination. In the view of the presented case studies, the MAS structure is found to be effective in assigning different operations and tasks of a project to the specific agents that will be responsible for their realization. Using a combination of strategic and tactical planning methods, the MAS is able to effectively provide readily executable guidance/control for equipment operators considering a variety of safety issues

Conference on Intelligent Robotics in Field, Factory, Service, and Space (CIRFFSS 1994), volume 1

The AIAA/NASA Conference on Intelligent Robotics in Field, Factory, Service, and Space (CIRFFSS '94) was originally proposed because of the strong belief that America's problems of global economic competitiveness and job creation and preservation can partly be solved by the use of intelligent robotics, which are also required for human space exploration missions. Individual sessions addressed nuclear industry, agile manufacturing, security/building monitoring, on-orbit applications, vision and sensing technologies, situated control and low-level control, robotic systems architecture, environmental restoration and waste management, robotic remanufacturing, and healthcare applications

Development of Walk Assistive Orthoses for Elderly

The proportion of elderly people is rapidly growing and the resources to help them will soon be insufficient. An important difficulty faced by the seniors is locomotion. Among the conditions that may be responsible for gait impairment, the reduced muscular force is one of the most frequent in elderly. This thesis focuses on the design and the evaluation of new solutions for assisting people with reduced vigor. Robotic orthoses are then used to support critical movements required for walking. Over the last two decades, the use of actuated orthotic devices for helping people suffering from gait disorders has been made possible. Recently, autonomous devices have even enabled spinal cord injured patients to walk again by mobilizing their paralyzed limbs. Addressing a completely different population, similar devices have been developed to augment healthy users' capabilities, for instance when heavy loads need to be carried. In this case, the wearer is in charge of the movements and the device simply follows the imposed trajectories. Extra load can then be carried by the exoskeleton without being felt by the user. The walk assistive devices developed as part of this thesis being intended for the elderly, they are at the intersection between these two classes of robotic orthosis. Indeed, most of the seniors who have difficulties to walk are able to move and therefore the mobilization devices are not adapted to them. Even though they need assistance, they surely do not want to have their movements imposed by a robotic device. The performance augmentation exoskeletons cannot help them either, as they simply follow the movements and only reject the external perturbations. A device that follows their movements and that adds the right amount of force when needed is therefore required. In order to achieve the demanding characteristics associated with assistive devices, new actuation solutions based on conventional electric motors are proposed. The combination of specifications in terms of overall weight, required assistance torque, dynamics capabilities or transparency when no support is provided is undeniably challenging. Various mechanisms are therefore presented to address these requirements. Two prototypes based on the proposed solutions are presented. The first one is based on a ball-screw transmission combined with linkages which provides a transmission ratio that is adapted to multiple walk related activities. The second one uses a transmission with clutches and an inversion mechanism which notably limits the losses due to the inertia of the actuation and greatly improves the natural transparency. In order to limit the obstructiveness of the assistive device, we propose to use partial devices that support specific movements. Two studies about the influence of such partial devices on gait are therefore presented. The first one focuses on identifying the potential sources of gait disturbance that orthotic device can induce. The second examines the effects of an assistive controller implemented on one of the developed prototypes. These studies demonstrate that even though the passive influence of a hip assistive orthosis on kinematic patterns is limited, the metabolic cost is increased. A moderate assistance cannot compensate for this undesirable effect but a link between the hip assistance and the ankle trajectory could be established. This is of major importance as the elderly tend to compensate for their weak ankle muscles with their hips

Volume 1 – Symposium: Tuesday, March 8

Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Components:Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Component

Proceedings of the 8th international conference on disability, virtual reality and associated technologies (ICDVRAT 2010)

The proceedings of the conferenc