walk through programming for industrial applications

Abstract Collaboration between humans and robots is increasingly desired in several application domains, including the manufacturing domain. The paper describes a software control architecture for industrial robotic applications allowing human-robot cooperation during the programming phase of a robotic task. The control architecture is based on admittance control and tool dynamics compensation for implementing walk-through programming and manual guidance. Further steps to integrate this system on a real set-up include the robot kinematics and a socket communication that sends a binary file to the robot

A survey of robot manipulation in contact

In this survey, we present the current status on robots performing manipulation tasks that require varying contact with the environment, such that the robot must either implicitly or explicitly control the contact force with the environment to complete the task. Robots can perform more and more manipulation tasks that are still done by humans, and there is a growing number of publications on the topics of (1) performing tasks that always require contact and (2) mitigating uncertainty by leveraging the environment in tasks that, under perfect information, could be performed without contact. The recent trends have seen robots perform tasks earlier left for humans, such as massage, and in the classical tasks, such as peg-in-hole, there is a more efficient generalization to other similar tasks, better error tolerance, and faster planning or learning of the tasks. Thus, in this survey we cover the current stage of robots performing such tasks, starting from surveying all the different in-contact tasks robots can perform, observing how these tasks are controlled and represented, and finally presenting the learning and planning of the skills required to complete these tasks

Design and Control of Robotic Systems for Lower Limb Stroke Rehabilitation

Lower extremity stroke rehabilitation exhausts considerable health care resources, is labor intensive, and provides mostly qualitative metrics of patient recovery. To overcome these issues, robots can assist patients in physically manipulating their affected limb and measure the output motion. The robots that have been currently designed, however, provide assistance over a limited set of training motions, are not portable for in-home and in-clinic use, have high cost and may not provide sufficient safety or performance. This thesis proposes the idea of incorporating a mobile drive base into lower extremity rehabilitation robots to create a portable, inherently safe system that provides assistance over a wide range of training motions. A set of rehabilitative motion tasks were established and a six-degree-of-freedom (DOF) motion and force-sensing system was designed to meet high-power, large workspace, and affordability requirements. An admittance controller was implemented, and the feasibility of using this portable, low-cost system for movement assistance was shown through tests on a healthy individual. An improved version of the robot was then developed that added torque sensing and known joint elasticity for use in future clinical testing with a flexible-joint impedance controller

Singularity Avoidance for Cart-Mounted Hand-Guided Collaborative Robots: A Variational Approach

Most collaborative robots (cobots) can be taught by hand guiding: essentially, by manually jogging the robot, an operator teaches some configurations to be employed as via points. Based on those via points, Cartesian end-effector trajectories such as straight lines, circular arcs or splines are then constructed. Such methods can, in principle, be employed for cart-mounted cobots (i.e., when the jogging involves one or two linear axes, besides the cobot axes). However, in some applications, the sole imposition of via points in Cartesian space is not sufficient. On the contrary, albeit the overall system is redundant, (i) the via points must be reached at the taught joint configurations, and (ii) the undesirable singularity (and near-singularity) conditions must be avoided. The naive approach, consisting of setting the cart trajectory beforehand (for instance, by imposing a linear-in-time motion law that crosses the taught cart configurations), satisfies the first need, but does not guarantee the satisfaction of the second. Here, we propose an approach consisting of (i) a novel strategy for decoupling the planning of the cart trajectory and that of the robot joints, and (ii) a novel variational technique for computing the former in a singularity-aware fashion, ensuring the avoidance of a class of workspace singularity and near-singularity configurations

Interface Design for Physical Human-Robot Interaction using sensorless control

The rapid increase in the usage of robots has made interaction between a human and a robot a crucial field of research. Physical human–robot interaction constitutes a relevant and growing research area. Nowadays robots are used in almost all areas of life, such as in households, for education and in medicine. Therefore, many research studies are being conducted on ergonomic human–robot interfaces enabling people to communicate, collaborate and to teach a robot through physical interaction.This thesis is focused on developing a physical human-robot interface by means of which the user is able to control a walking humanoid by exerting force. Through physical contact with the robot arm, a human can influence the direction and velocity of the robot walk. In other words, the user leads the humanoid by the hand, and the robot compensates this external force by following the user.The developed interface offers a method of sensorless force control. Instead of the traditional approach using force/torque measurement, the fact that a DC motor’s torque is proportional to the armature current was applied. Two different control algorithms were implemented and compared. Consequently, a usability test was conducted for different interfaces to find the one which was the most ergonomic

Design, implementation and control of an overground gait and balance trainer with an active pelvis-hip exoskeleton

Human locomotion is crucial for performing activities of daily living and any disability in gait causes a significant decrease in the quality of life. Gait rehabilitation therapy is imperative to improve adverse effects caused by such disabilities. Gait therapies are known to be more effective when they are intense, repetitive, and allow for active involvement of patients. Robotic devices excel in performing repetitive gait rehabilitation therapies as they can eliminate the physical burden of the therapist, enable safe and versatile training with increased intensity, while allowing quantitative measurements of patient progress. Gait therapies need to be applied to specific joints of patients such that the joints work in a coordinated and repetitious sequence to generate a natural gait pattern. Six determinants of gait pattern have been identified that lead to efficient locomotion and any irregularities in these determinants result in pathological gaits. Three of these six basic gait determinants include movements of the pelvic joint; therefore, an effective gait rehabilitation robot is expected to be capable of controlling the movements of the human pelvis. We present the design, implementation, control, and experimental verification of AssistOn-Gait, a robot-assisted trainer, for restoration and improvement of gait and balance of patients with disabilities affecting their lower extremities. In addition to overground gait and balance training, AssistOn-Gait can deliver pelvis-hip exercises aimed to correct compensatory movements arising from abnormal gait patterns, extending the type of therapies that can be administered using lower extremity exoskeletons. AssistOn-Gait features a modular design, consisting of an impedance controlled, self-aligning pelvis-hip exoskeleton, supported by a motion controlled holonomic mobile platform and a series-elastic body weight support system. The pelvis-hip exoskeleton possesses 7 active degrees of freedom to independently control the rotation of the each hip in the sagittal plane along with the pelvic rotation, the pelvic tilt, lateral pelvic displacement, and the pelvic displacements in the sagittal plane. The series elastic body weight support system can provide dynamic unloading to support a percentage of a patient's weight, while also compensating for the inertial forces caused by the vertical movements of the body. The holonomic mobile base can track the movements of patients on flat surfaces, allowing patients to walk naturally, start/stop motion, vary their speed, sidestep to maintain balance, and turn to change their walking direction. Each of these modules can be used independently or in combination with each other, to provide different configurations for overground and treadmill based training with and without dynamic body weight support. The pelvis-hip exoskeleton of AssistOn-Gait is constructed using two passively backdrivable planar parallel mechanisms connected to the patient with a custom harness, to enable both passive movements and independent active impedance control of the pelvis-hip complex. Furthermore, the exoskeleton is self-aligning; it can automatically adjust the center of rotation of its joint axes, enabling an ideal match between patient's hip rotation axes and the device axes in the sagittal plane. This feature not only guarantees ergonomy and comfort throughout the therapy, but also extends the usable range of motion for the hip joint. Moreover, this feature significantly shortens the setup time required to attach the patient to the exoskeleton. The exoskeleton can also be used to implement virtual constraints to ensure coordination and synchronization between various degrees of freedom of the pelvis-hip complex and to assist patients as-needed for natural gait cycles. The overall kinematics of AssistOn-Gait is redundant, as the exoskeleton module spans all the degrees of freedom covered by the mobile platform. Furthermore, the device features dual layer actuation, since the exoskeleton module is designed for force control with good transparency, while the mobile base is designed for motion control to carry the weight of the patient and the exoskeleton. The kinematically redundant dual layer actuation enables the mobile base of the system to be controlled using workspace centering control strategy without the need for any additional sensors, since the patient movements are readily measured by the exoskeleton module. The workspace centering controller ensures that the workspace limits of the exoskeleton module are not reached, decoupling the dynamics of the mobile base from the dynamics of the exoskeleton. Consequently, AssistOn-Gait possesses virtually unlimited workspace, while featuring the same output impedance and force rendering performance as its exoskeleton module. The mobile platform can also be used to generate virtual fixtures to guide patient movements. The ergonomy and useability of AssistOn-Gait have been tested with several human subject experiments. The experimental results verify that AssistOn-Gait can achieve the desired level of ergonomy and passive backdrivability, as the gait patterns with the device in zero impedance mode are shown not to significantly deviate from the natural gait of the subjects. Furthermore, virtual constraints and force-feedback assistance provided by AssistOn-Gait have been shown to be adequate to ensure repeatability of desired corrective gait patterns

Design and Development of a Low Cost Platform to Facilitate Post-Stroke Rehabilitation of the Elbow/Shoulder Region

For post-stroke rehabilitation of the upper limbs, increased amounts of therapy are directly related to improved rehabilitation outcomes. As such, a low cost therapy platform is proposed suitable for facilitating active therapy and administering activeassist therapy to the shoulder/elbow region of the upper limbs of individuals post-stroke in a local clinic or domestic setting. Enabling a person to undergo intensive rehabilitation therapy outside of a rehabilitation hospital setting permits the amount of therapy administered to be maximised. While studies have shown that technological approaches to post-stroke rehabilitation do not produce better outcomes than equal amounts of traditional therapy in a rehabilitation hospital setting, a technological approach has the potential to have significant benefits when that therapy is being undertaken in a local clinic or domestic setting, where the individual undergoing therapy is relatively unsupervised. These benefits largely relate to a technological approach being more motivational for the person than an equivalent manual approach. However, for such an approach to be economically viable, effective, low cost devices are required. This document presents and critically discusses the design of this proposed low cost therapy platform along with possible routes for its further development

Personalization and Adaptation in Physical Human-Robot Interaction

Gopinathan S. Personalization and Adaptation in Physical Human-Robot Interaction. Bielefeld: Universität Bielefeld; 2019.Recent advancements in physical human-robot interaction (pHRI) makes it possible for compliant robots to assist the human counterpart while closely working together. An ideal control mode designed for pHRI should be easy to handle, intuitive to use, ergonomic and adaptive to human habits and preferences. The major stumbling block in achieving this is that each user has varying physical capabilities and characteristics. This variance in the user behavior and other features is often high and rather unpredictable, which hinders the development of such systems. To tackle this problem, the idea of personalized adaptive stiffness control for pHRI is introduced in this thesis. Extensive user-studies are conducted in scope of this thesis and various control modes for pHRI are proposed and evaluated using appropriate user-studies. Both naive and expert users were considered in the user-studies and inferences from each study were used to improve the control mode to be better suited for pHRI. The thesis follows a meticulous research plan, an initial user-study confirms the im- portance of pHRI and kinesthetic guidance in industrial tasks. Subsequently, the user interactive force based adaptation is proposed and a second user-study is conducted where it is compared with standard control modes for pHRI. Importance of task specific param- eters and the need for combining the task and human factors emerged from the results of the second user-study. In the next phase manipulability based approaches which com- bine both task and human parameters are proposed and validated by conducting a third user-study. In the final phase a fourth user-study is conducted where the proposed con- trol modes are compared against more complex methods that have been proposed in the literature. The importance of human physical factors and needs for human centered systems for pHRI is validated in this thesis. The results show that including these human factors not only improve the performance but also improves the interaction quality and reduces the complexity of the pHRI

Human-robot coexistence and interaction in open industrial cells

Recent research results on human\u2013robot interaction and collaborative robotics are leaving behind the traditional paradigm of robots living in a separated space inside safety cages, allowing humans and robot to work together for completing an increasing number of complex industrial tasks. In this context, safety of the human operator is a main concern. In this paper, we present a framework for ensuring human safety in a robotic cell that allows human\u2013robot coexistence and dependable interaction. The framework is based on a layered control architecture that exploits an effective algorithm for online monitoring of relative human\u2013robot distance using depth sensors. This method allows to modify in real time the robot behavior depending on the user position, without limiting the operative robot workspace in a too conservative way. In order to guarantee redundancy and diversity at the safety level, additional certified laser scanners monitor human\u2013robot proximity in the cell and safe communication protocols and logical units are used for the smooth integration with an industrial software for safe low-level robot control. The implemented concept includes a smart human-machine interface to support in-process collaborative activities and for a contactless interaction with gesture recognition of operator commands. Coexistence and interaction are illustrated and tested in an industrial cell, in which a robot moves a tool that measures the quality of a polished metallic part while the operator performs a close evaluation of the same workpiece

Implementation of a acceleration estimator based compensation scheme to increase load data accuracy for a robotic testing system for CPR-manikins

Laerdal Medical is a producer of Cardiopulmonary Resuscitation (CPR) training manikins, all of which undergo rigorous endurance and accuracy testing. This work proposes an acceleration estimator based compensation scheme for a industrial robot manipulator product testing system with the intention of increasing load data accuracy for the purpose of product review and calibration. As part of the compensation scheme four different acceleration estimators are implemented and compared. Results indicate that the compensation scheme increases the load data accuracy by 1.5 - 6 % of the reference value depending on compression depth and spring rate. However the accuracy goal of 0.4 [kg] is not reached. The work has also uncovered the presence of position error in the robot. Thus, further improvement to the compensation scheme and positional error compensation is required