Rishi K. Malhan

Bio: Rishi K. Malhan is an academic researcher from University of Southern California. The author has contributed to research in topics: Robot & Computer science. The author has an hindex of 9, co-authored 25 publications receiving 192 citations.

Expanding capabilities of additive manufacturing through use of robotics technologies: A survey

Abstract: Robots are versatile machines that can perform complex manipulation operations. Recent advances in industrial robotics make robots useful in a wide variety of manufacturing processes. Several recent efforts have demonstrated how robots can be used in additive manufacturing (AM) processes. This paper surveys the work focused on expanding the functional capabilities of AM processes using robots. We identify the following main capabilities realized by performing AM using robots: (1) multi-directional fabrication, (2) conformal deposition, (3) assembling prefabricated components in AM, (4) supportless AM, and (5) large-scale AM. We classify the recent literature in this area in terms of mechanisms, kinematic degrees of freedom (DOF) of the system, types of AM process, and materials. Finally, we discuss the limitations of the current work and the opportunities for future research in this area.

Building free-form thin shell parts using supportless extrusion-based additive manufacturing

Abstract: Conventional material extrusion additive manufacturing is capable of building complex structures. Overhanging features require the use of support structures. Printing the support structure requires additional time and material. Conventional processes need time to remove support material and may lead to degraded surface finish. The use of support structures can be avoided by dynamically reorienting the build-platform. This paper presents a novel approach to build accurate thin shell parts using supportless extrusion-based additive manufacturing. We describe the layer slicing algorithm, the tool-path planning algorithm, and the neural network-based compensated trajectory generation scheme to use a 3 degree of freedom build-platform and a 3 degree of freedom extrusion tool to build accurate thin shell parts using two manipulators. Such thin shell parts cannot be built without supports by previous supportless AM processes. We illustrate the usefulness of our algorithms by building several thin shell parts.

Identifying Feasible Workpiece Placement with Respect to Redundant Manipulator for Complex Manufacturing Tasks

Abstract: Successfully completing a complex manufacturing task requires finding a feasible placement of the workpiece in the robot workspace. The workpiece placement should be such that the task surfaces on the workpiece are reachable by the robot, the robot can apply the required forces, and the end-effector/tool can move with the desired velocity. This paper formulates the problem of identifying a feasible placement as a non-linear optimization problem over the constraint violation functions. This is a computationally challenging problem. We show that this problem can be solved by successively searching for the solution by incrementally applying different constraints. We demonstrate the feasibility of our approach using several complex workpieces.

Automated planning for robotic layup of composite prepreg

Abstract: Hand layup is a commonly used process for making composite structures from several plies of carbon-fiber prepreg. The process involves multiple human operators manipulating and conforming layers of prepreg to a mold. The manual layup process is ergonomically challenging, tedious, and limits throughput. Moreover, different operators may perform the process differently, and hence introduce inconsistency. We have developed a multi-robot cell to automate the layup process. A human expert provides a sequence to conform to the ply and types of end-effectors to be used as input to the system. The system automatically generates trajectories for the robots that can achieve the specified layup. Using the cell requires the automated generation of different types of plans. This paper addresses two main planning problems: (a) generating plans to grasp and manipulate the ply and (b) generating feasible robot trajectories. We use a hybrid-physics based simulator coupled with a state space search to find grasp plans. The system employs a strategy that applies constraints successively in a non-linear optimization formulation to identify suitable placements of the robots around the mold so that feasible trajectories can be generated. Our system can generate plans in a computationally efficient manner, and it can handle a wide variety of complex parts. We demonstrate the automated layup by conducting physical experiments on an industry-inspired mold using the generated plans.

Foundations of robotics : analysis and control

Abstract: Foundations of Robotics presents the fundamental concepts and methodologies for the analysis, design, and control of robot manipulators It explains the physical meaning of the concepts and equations used, and it provides, in an intuitively clear way, the necessary background in kinetics, linear algebra, and control theory Illustrative examples appear throughoutThe author begins by discussing typical robot manipulator mechanisms and their controllers He then devotes three chapters to the analysis of robot manipulator mechanisms He covers the kinematics of robot manipulators, describing the motion of manipulator links and objects related to manipulation A chapter on dynamics includes the derivation of the dynamic equations of motion, their use for control and simulation and the identification of inertial parameters The final chapter develops the concept of manipulabilityThe second half focuses on the control of robot manipulators Various position-control algorithms that guide the manipulator's end effector along a desired trajectory are described Two typical methods used to control the contact force between the end effector and its environments are detailed For manipulators with redundant degrees of freedom, a technique to develop control algorithms for active utilization of the redundancy is described Appendixes give compact reviews of the function atan2, pseudo inverses, singular-value decomposition, and Lyapunov stability theoryTsuneo Yoshikawa teaches in the Division of Applied Systems Science in Kyoto University's Faculty of Engineering

Methods and materials for additive manufacturing: A critical review on advancements and challenges

Abstract: Additive Manufacturing (AM) is the significantly progressing field in terms of methods, materials, and performance of fabricated parts. Periodical evaluation on the understanding of AM processes and its evolution is needed since the field is growing rapidly. To address this requirement, this paper presents a detailed review of the Additive Manufacturing (AM) methods, materials used, and challenges associated with them. A critical review of the state of art materials in the categories such as metals and alloys, polymers, ceramics, and biomaterials are presented along with their applications, benefits, and the problems associated with the formation of microstructures, mechanical properties, and controlling process parameters. The perspectives and the status of different materials on the fabrication of thin-walled structures using AM techniques have also been discussed. Additionally, the main challenges with AM techniques such as inaccuracy, surface quality, reinforcement distribution, and other common problems identified from the literature are presented. On the whole, this paper provides a comprehensive outlook on AM techniques, challenges, and future research directions.

Expanding capabilities of additive manufacturing through use of robotics technologies: A survey

Abstract: Robots are versatile machines that can perform complex manipulation operations. Recent advances in industrial robotics make robots useful in a wide variety of manufacturing processes. Several recent efforts have demonstrated how robots can be used in additive manufacturing (AM) processes. This paper surveys the work focused on expanding the functional capabilities of AM processes using robots. We identify the following main capabilities realized by performing AM using robots: (1) multi-directional fabrication, (2) conformal deposition, (3) assembling prefabricated components in AM, (4) supportless AM, and (5) large-scale AM. We classify the recent literature in this area in terms of mechanisms, kinematic degrees of freedom (DOF) of the system, types of AM process, and materials. Finally, we discuss the limitations of the current work and the opportunities for future research in this area.

A Survey on AI-Driven Digital Twins in Industry 4.0: Smart Manufacturing and Advanced Robotics

Abstract: Digital twin (DT) and artificial intelligence (AI) technologies have grown rapidly in recent years and are considered by both academia and industry to be key enablers for Industry 4.0. As a digital replica of a physical entity, the basis of DT is the infrastructure and data, the core is the algorithm and model, and the application is the software and service. The grounding of DT and AI in industrial sectors is even more dependent on the systematic and in-depth integration of domain-specific expertise. This survey comprehensively reviews over 300 manuscripts on AI-driven DT technologies of Industry 4.0 used over the past five years and summarizes their general developments and the current state of AI-integration in the fields of smart manufacturing and advanced robotics. These cover conventional sophisticated metal machining and industrial automation as well as emerging techniques, such as 3D printing and human–robot interaction/cooperation. Furthermore, advantages of AI-driven DTs in the context of sustainable development are elaborated. Practical challenges and development prospects of AI-driven DTs are discussed with a respective focus on different levels. A route for AI-integration in multiscale/fidelity DTs with multiscale/fidelity data sources in Industry 4.0 is outlined.