Conventional Robotic Systems Research Articles

Actuator fault-tolerant control study of an underwater robot with four rotatable thrusters

This paper presents the mathematical design and implementation of an actuator fault-tolerant control system for an underwater robot having four rotatable thrusters where the rotatable action of the thrusters is unconventional to a conventional underwater robotic system. Initially, the dynamic model of the robot is presented. Later, a motion control scheme using a backstepping control technique is made to track a desired spatial trajectory. Two techniques of active fault tolerance control viz., Elimination of Column Method, and Weighted-Pseudo Inverse Method are implemented successfully for single actuator faults on an infinity-shaped trajectory, which is a critical aspect of this study as most of the previous literature reported only on set point control. The methods mentioned above are extended to multiple thrusters failure, but both of them could not handle more than a single thruster failure. Hence, an attempt is made to accommodate two thrusters' failure through the line of sight approach by considering the vehicle as under-actuated. The desired vehicle performance is achieved with this approach. Finally, oceanic currents are modeled to simulate the effectiveness of the methods discussed in the paper to prove the performance capabilities of the control system and fault accommodation schemes under realistic conditions.

3D Printable Linear Soft Vacuum Actuators: Their Modeling, Performance Quantification and Application in Soft Robotic Systems

Conventional robotic systems have proved their versatility in the industry where complex tasks requiring high force, high speed and high precision are desired. However, these rigid-bodied systems cannot collaborate safely with humans. Soft robots which are primarily made of highly compliant materials bring robots and humans together by operating safely in unstructured environments. Soft robots demand dexterous soft actuators that preserve or enhance their softness and safety features. This article reports on modeling, performance quantification, and soft robotic applications of directly three-dimensional (3-D) printed linear soft vacuum actuators (LSOVA), that are manufactured in a single step, using a low-cost and affordable open-source fused deposition modeling 3-D printer. Numerical and experimental results presented show that LSOVA have multiple advantages including high bandwidth (∼6.49 Hz), high output force (∼27 N) and long lifetime (∼21 500 cycles). LSOVA blocked force and linear stroke can be predicted accurately using finite element and analytical models. Furthermore, LSOVA are scalable. The soft actuators can be either assembled in parallel as a bundle, where a linear relationship exists between the number of actuators and the output force or can be scaled up in terms of internal volume where a linear relationship exists between the output force and the internal volume of a single actuator. Finally, LSOVAs were tailored for various robotic applications including soft crawling robots for navigation in tubular systems, soft parallel manipulators for pick and place tasks, soft artificial muscles, soft prosthetic fingers for prosthetic hands, and soft adaptive grippers for gripping applications.

Contactless Manipulation of Soft Robots.

In recent years, jointless soft robots have demonstrated various curvilinear motions unlike conventional robotic systems requiring complex mechanical joints and electrical design principles. The materials employed to construct soft robots are mainly programmable anisotropic polymeric materials to achieve contactless manipulation of miniaturized and lightweight soft robots through their anisotropic strain responsivity to external stimuli. Although reviews on soft actuators are extensive, those on untethered soft robots are scant. In this study, we focus on the recent progress in the manipulation of untethered soft robots upon receiving external stimuli such as magnetic fields, light, humidity, and organic solvents. For each external stimulus, we provide an overview of the working principles along with the characteristics of programmable anisotropic materials and polymeric composites used in soft robotic systems. In addition, potential applications for untethered soft robots are discussed based on the physicochemical properties of programmable anisotropic materials for the given external stimuli.

Transition from multiport to single-site surgery: A single institution experience in robotic supracervical hysterectomy for benign gynecological diseases

ObjectiveTo share our experience of transition from multiport to single-site robotic surgery for benign gynecological conditions as well as to assess the selection criteria of candidates for robotic single-site supracervical hysterectomy (RSSH). Materials and methodsA retrospective review was conducted on patients undergoing robotic supracervical hysterectomy by a single surgeon in a single institute between June 2014 and December 2017. Patients who underwent additional procedures along with supracervical hysterectomy and who had unexpectant corpus malignancy proved pathologically were excluded from comparisons between patients undergoing RSSH and robotic multiport supracervical hysterectomy (RMSH). ResultsBetween June 2014 and December 2017, we accomplished 26 RSSH and 57 RMSH. There were no conversions, intraoperative complications, and readmissions within 30 days after surgery. In the RSSH group, the mean uterine weight was 264.6 ± 140.9 g with mean docking time of 15.8 ± 5.5 min, mean console time of 61.1 ± 35.6 min and mean operative time of 140.3 ± 34.4 min. In comparison to the RMSH group, the percentage of overweight/obese patients was lower (p = 0.018) and the uterine size was smaller (p < 0.001) with adenomyosis diagnosed more frequently (p = 0.002) in the RSSH group. While the operative time in the RSSH group was significantly shorter (p = 0.002), the RSSH group took longer time in docking (p < 0.001) and comparable time in console (p = 0.254). In view of chronological change, docking time and console time in the RMSH group remained steady, whereas steep decreases were observed in the RSSH group. The intraoperative blood loss and hemoglobin drop were comparable. The length of hospital stay was significantly shorter in the RSSH group (p = 0.005). ConclusionTransition from multiport to single-site surgery can be smooth for a surgical team experienced in the conventional multiport robotic system. RSSH is safe and feasible in properly selected patients.

Modular Reconfigurable Robotics

This article reviews the current state of the art in the development of modular reconfigurable robot (MRR) systems and suggests promising future research directions. A wide variety of MRR systems have been presented to date, and these robots promise to be versatile, robust, and low cost compared with other conventional robot systems. MRR systems thus have the potential to outperform traditional systems with a fixed morphology when carrying out tasks that require a high level of flexibility. We begin by introducing the taxonomy of MRRs based on their hardware architecture. We then examine recent progress in the hardware and the software technologies for MRRs, along with remaining technical issues. We conclude with a discussion of open challenges and future research directions.

Quantitative Evaluation of Streaming Image Quality for Robot Teleoperations

To develop a measure of streaming video quality for remotely operated robots, we need to know the critical factors for the quality of control. Controlling robots remotely is crucial for disaster response, and many attempts have been made to create such systems. Wireless communication, which is used in remote-control systems for unmanned vehicles, changes dynamically and the streaming quality also changes with the quality of the network. However, wireless conditions are not typically measured in conventional robot systems. In this paper, to develop a quality measure for remote control using video properties, we investigate critical factors such as delay and the degradation of image quality. We also introduce the concept of a quality-of-control measure using delay and degradation of image-quality curves from simulation environments, and we discuss the impacts of changing communication delay and degrading image quality on remote-control robots.

Impact of a Wireless System Upon Verbal Communication in a Simulated Robotic Operating Theater

ObjectiveTo compare the efficacy of communication via the standard Da Vinci Si speaker system with a wireless, hands-free audio system in a prospective blinded study. MethodsNine hundred and sixty surgical phrases were spoken in a simulated robotic operating room (OR), including 480 phrases expressed via the Da Vinci Si speakers and 480 phrases expressed through a wireless, hands-free system. Using a dual console robotic system, communication was evaluated. Wireless headsets were given to the console and assistant robotic console surgeons, bedside assistant, anesthesiologist, and circulating nurse. An accurate response was defined as hearing the phrase correctly and transcribing it on a data sheet. The primary outcome was the number of correct phrases recorded during the study and secondary outcomes included subjective clarity and effectiveness of communication reported using a Likert scale. ResultsOverall, the wireless, hands-free system increased the accuracy of communication (390/480 [81.3%]) compared to the conventional robotic system (310/480 [64.4%]; P <.001). The bedside assistant, anesthesiologist, and circulating nurse had significantly fewer correct phrases recorded than the assistant robotic console surgeon when using the robotic speakers (P <.05 for all). In contrast, there were no significant differences in the number of correct phrases recorded between different positions when using the wireless system. Subjectively, the wireless system resulted in improved clarity and effectiveness of communication (P = .021; P <.001, respectively). ConclusionRobotic operating systems have intrinsic barriers to effective communication between the surgeon and the rest of the operating room team. Improved communication could reduce surgical errors and improve patient safety.

Super-low friction and lightweight hydraulic cylinder using multi-directional forging magnesium alloy and its application to robotic leg

One of the most important missions for robots is to operate in severe environments, and these situations require robots to have ‘toughness’ which can overcome large shocks, degraded communication quality, unexpected condition, and other critical accidents. Although there are many kinds of approaches to realize tough robotic systems, developing a tough actuators is one of the key technologies for them. We focus on hydraulic actuators and attempt to develop a tough robotic actuator with greater toughness than the electromagnetic actuators used in conventional robotic systems. In general, hydraulic actuators have enough toughness for severe environments, but their controllability and lightness are insufficient for robot systems. Herein, we propose novel hydraulic actuators that realizes lightweight with a multidirectional-forging magnesium alloy and have high controllability by low friction pistons. Prototypes were developed to examine the fundamental characteristics of the actuators and compare the two approaches for the low-friction pistons: one is based on a packing mechanism using an elastic restoring pressure, and the other utilizes a fluid-bearing technology. After basic experiments, the prototype was applied to a robotic leg to verify their potential in actual robotic systems. The robotic leg successfully jumped 260 mm in height with 21 MPa.

Adaptive neural network control of cable-driven parallel robots with input saturation

In this paper, an adaptive neural trajectory tracking controller with a bounded-input property is developed for cable-driven parallel robots (CDPRs). Due to the fact that the cables in these robotic systems should always remain in tension in a trajectory tracking task, a more precise tracking controller is needed for CDPRs comparing to the conventional rigid-link robotic systems. To achieve this objective, this paper proposes a new nonlinear controller with a learning ability for the robot dynamics. The controller includes an adaptive multi-layer neural network to compensate for the modeling uncertainties of the system, and utilizes an auxiliary dynamics to provide a priori bounded tension command for the cables. In addition to this novelty, a bounded-input controller is designed for the dynamics of the actuators, coupled with gearboxes, in order to follow the tensions, defined through the controller of robot dynamics. The boundedness feature of the controller facilitates considering the upper limit of the actuators in choosing the control gains. Stability of the whole system is well studied, and the uniformly ultimately bounded stability is guaranteed. The effectiveness of the proposed control scheme is validated through simulations on a 4-cable planar robot in both nominal and perturbed conditions.

Automated Synthesis of Passive Dynamic Brachiating Robots Using a Simulation-Driven Graph Grammar Method

Passive dynamic systems have the advantage over conventional robotic systems that they do not require actuators and control. Brachiating, in particular, involves the swinging motion of an animal from one branch to the next. Such systems are usually designed manually by human designers and often are bio-inspired. However, a computational design approach has the capability to search vast design spaces and find solutions that go beyond those possible by manual design. This paper addresses the automated design of passive dynamic systems by introducing a graph grammar-based method that integrates dynamic simulation to evaluate and evolve configurations. In particular, the method is shown to find different, new solutions to the problem of the design of two-dimensional passive, dynamic, continuous contact, brachiating robots. The presented graph grammar rules preserve symmetry among robot topologies. A separation of parametric multi-objective optimization and topologic synthesis is proposed, considering four objectives: number of successful swings, deviation from cyclic motion, required space, and number of bodies. The results show that multiple solutions with varying complexity are found that trade-off cyclic motion and the space required. Compared to research on automated design synthesis of actuated and controlled robotic systems, this paper contributes a new method for passive dynamic systems that integrates dynamic simulation.

Parasitic Robot System for Waypoint Navigation of Turtle

In research on small mobile robots and biomimetic robots, locomotion ability remains a major issue despite many advances in technology. However, evolution has led to there being many real animals capable of excellent locomotion. This paper presents a “parasitic robot system” whereby locomotion abilities of an animal are applied to a robot task. We chose a turtle as our first host animal and designed a parasitic robot that can perform “operant conditioning”. The parasitic robot, which is attached to the turtle, can induce object-tracking behavior of the turtle toward a Light Emitting Diode (LED) and positively reinforce the behavior through repeated stimulus-response interaction. After training sessions over five weeks, the robot could successfully control the direction of movement of the trained turtles in the waypoint navigation task. This hybrid animal-robot interaction system could provide an alternative solution to some of the limitations of conventional mobile robot systems in various fields, and could also act as a useful interaction system for the behavioral sciences.

Development and control of shaped metal deposition process using tungsten inert gas arc heat source in additive layered manufacturing

Tungsten inert gas arc welding–based shaped metal deposition is a novel additive manufacturing technology which can be used for fabricating solid dense parts by melting a cold wire on a substrate in a layer-by-layer manner via continuous DC arc heat. The shaped metal deposition method would be an alternative way to traditional manufacturing methods, especially for complex featured and large-scale solid parts manufacturing, and it is particularly used for aerospace structural components, manufacturing, and repairing of die/molds and middle-sized dense parts. This article presents the designing, constructing, and controlling of an additive manufacturing system using tungsten inert gas plus wire–based shaped metal deposition method. The aim of this work is to design and develop tungsten inert gas plus wire–based shaped metal deposition system to be used for fabricating different components directly from computer-aided design data with minimum time consumed in programming and less boring task compared to conventional robotic systems. So, this article covers the important design steps from computer-aided design data to the final deposited part. The developed additive system is capable of producing near-net-shaped components of sizes not exceeding 400 mm in three-dimensional directly from computer-aided design drawing. The results showed that the developed system succeeded to produce near-net-shaped parts for various features of SS308LSi components. Additionally, workshop tests have been conducted in order to verify the capability and reliability of the developed additive manufacturing system. The developed system is also capable of reducing the buy-to-fly ratio from 5 to 2 by reducing waste material from 1717 to 268 g for the sample components.

Teach Less Robotic System for Deburring Workpieces of Various Shapes

In the case of conventional industrial robot systems, operators have to write robot-language programs for each type of workpiece. This is an onerous task, especially when each workpiece has a different shape. In this paper, a teaching-less robot system for the finishing of two-dimensional workpieces of various shapes and thicknesses using computer vision is proposed. The robot system does not require shape information for the workpiece to be included in the CAD data or to be input by the operator. Each workpiece shape is acquired by segmenting edges into straight lines and circular arcs from the image data of the workpiece. The robot-language program for each workpiece is generated automatically from the workpiece shape data and finishing condition data. The effectiveness of the proposed method is verified by experiments using a newly developed robot system. This method provides a compact and inexpensive finishing robot system which reduces the programming timing.

Robotic goalie with 3 ms reaction time at 4% CPU load using event-based dynamic vision sensor

Conventional vision-based robotic systems that must operate quickly require high video frame rates and consequently high computational costs. Visual response latencies are lower-bound by the frame period, e.g., 20 ms for 50 Hz frame rate. This paper shows how an asynchronous neuromorphic dynamic vision sensor (DVS) silicon retina is used to build a fast self-calibrating robotic goalie, which offers high update rates and low latency at low CPU load. Independent and asynchronous per pixel illumination change events from the DVS signify moving objects and are used in software to track multiple balls. Motor actions to block the most “threatening” ball are based on measured ball positions and velocities. The goalie also sees its single-axis goalie arm and calibrates the motor output map during idle periods so that it can plan open-loop arm movements to desired visual locations. Blocking capability is about 80% for balls shot from 1 m from the goal even with the fastest-shots, and approaches 100% accuracy when the ball does not beat the limits of the servo motor to move the arm to the necessary position in time. Running with standard USB buses under a standard preemptive multitasking operating system (Windows), the goalie robot achieves median update rates of 550 Hz, with latencies of 2.2 ± 2 ms from ball movement to motor command at a peak CPU load of less than 4%. Practical observations and measurements of USB device latency are provided1.

Online Rapid Vision Integration for a Robotized China Plates Manufacturing Line

Abstract In conventional robot systems the different robot parts (sensors, processing elements and actuators) are combined together in a compact, self contained system. The need for faster development and deployment, system reconfigurability and flexibility required the introduction of rapid deployment automation for robot systems in flexible manufacturing cells. Vision sensors are one of the most important sensors in robot systems. When constructing a new robot system, it is desirable that vision and image processing components are just as easily integrated as any other robot components. In some situations robot stations must be upgraded with vision systems in order to accomplish new tasks or to enhance the current work, here the Rapid Deployment Automation concept is the base to solve such problems in a shorter time having the smallest impact over the production flow in terms of production downtime. The paper describes an RDA solution of vision upgrade for robot stations in a china objects production plant.

空気圧人工筋による人に対して安全な多自由度ロボットアーム技術の開発

Robotic systems intended for domestic housekeeping or elderly care tasks will have interaction with humans and therefore demand an intrinsically safe design. Conventional robotic systems are driven by heavy, high power and high stiffness electric motors, making them unsafe for human coexistence. To overcome this problem, we have developed a robotic arm system using pneumatic muscle actuators, which is intrinsically safe given its low weight and pliant structure. In this paper we present the design of the robot arm and associated control system, showing that the robot has positioning and force control accuracy sufficient for daily domestic tasks.

Special issue on swarm robotics

Swarm robotics is a new approach to the coordination of multi-robot systems. In contrast with traditional multi-robot systems which use centralised or hierarchical control and communication systems in order to coordinate robots’ behaviours, swarm robotics adopts a decentralised approach in which the desired collective behaviours emerge from the local interactions between robots and their environment. Such emergent or self-organised collective behaviours are inspired by, and in some cases modelled on, the swarm intelligence observed in social insects. The potential for swarm robotics is considerable. Any task in which physically distributed objects need to be explored, surveyed, collected, harvested, rescued, or assembled into structures is a potential real-world application for swarm robotics. The key advantage of the swarm robotics approach is robustness, which manifests itself in a number of ways. Firstly, because a swarm of robots consists of a number of relatively simple and typically homogeneous robots, which are not pre-assigned to specific roles or tasks within the swarm, then the swarm can self-organise or dynamically re-organise the way individual robots are deployed. Secondly, and for the same reasons, the swarm approach is highly tolerant to the failure of individual robots. Thirdly, the fact that control is completely decentralised means that there is no common-mode failure point or vulnerability in the swarm. Indeed, it could be said that the high level of robustness evident in robotic swarms comes for free in the sense that it is intrinsic to the swarm robotics approach, which contrasts with the high engineering cost of fault tolerance in conventional robotic systems. The realisation of the potential of swarm robotics requires the solution of a number of very challenging problems. Firstly, in algorithm design: swarm roboticists face the problem of designing both the physical morphology and behaviours of the individual robots such that when those robots interact with each other and their environment, the desired overall collective behaviours will emerge. At present there are no principled approaches to the design of low-level behaviours for a given desired collective behaviour. Secondly, in implementation

Methods for highly accurate gripping of flexible micro parts

Today, handling and assembly of flexible micro-components such as thin wires or glass fibres with diameters down to a few micrometers and lateral dimensions up to a few meters is an important challenge in hybrid micro-assembly (Brecher and Peschke 2004). Production of flow sensors for respirators in medical engineering or coupling a fibre to an active visual component in optical data communication are examples of such applications. Such products have one thing in common: The assembly of their most sensitive functional components is often carried out manually since the handling and positioning technology either has to be specially developed and is costly or is non-existent (Weck and Peschke 2003). However, in most cases the manual assembly is very time consuming and its repeatability and positioning accuracy is not adequate (Carrozza et al. 2000); Petersen (2003). This disadvantage is obvious especially in the assembly of hybrid micro-optical telecommunication systems such as switches or power splitters, because the required mounting tolerances are less than a micron. A deviation of 100 nm in the alignment between the optical components and the glass fibres leads to noticeable and non-tolerable losses when coupling light into the fibres. With this background, fundamental studies are carried out at Fraunhofer IPT for the optimization of gripper geometry, gripper materials and gripping parameters for handling flexible micro-components such as glass fibres. The aim of these studies, shown in chapter 2 of this paper, is primarily to investigate the effects on the reproducibility of the positioning when gripping these highly sensitive micro-components and to derive gripper optimization strategies. A further aim is to develop a large scale integrated, adaptive, rugged and economical gripper system particularly for handling and alignment of flexible micro-components accurate to the sub-micron level. This gripper system can be used on conventional robot systems for carrying out micro-assembly operations. The robot system carries out the pre-positioning, the positioning tolerances necessary for the micro-assembly are subsequently realised directly at the tip of the gripper with a multi-axes system integrated into the gripper. Positioning systems that achieve the required positioning increments in the sub-micron range are existent (Scheller 2001). The problem of such systems is that they are normally highly sensitive against mechanical impact. Also their gripper integration is problematical due to a high weight and size dimensions in the decimetre range for each axis. In this paper the development of a highly robust gripper-integrable multi-axes system is presented.

1P1-E25 水中ロボットを追跡する水上支援機を利用した水中ロボットシステムの提案

Underwater robots can play a significant role in the investigations of underwater environment. However, conventional underwater robot systems that consist of underwater robot, operator and huge support ship have some problems such as propagation loss of acoustic wave, constraint of underwater robot behavior by umbilical cable. In this research, underwater robot systems with a Surface Support Vehicle that tracks an underwater robot are proposed. The Surface Support Vehicle is a compact surface vehicle having the functions of support ship and tracks an underwater robot autonomously. By installation of the Surface Support Vehicle, the problems of conventional underwater robot systems are resolved, and novel operation methods are realized. In this paper, the advantages of installation of the Surface Support Vehicle are explained and a effectiveness of the Surface Support Vehicle is verified by the experimental results in actual environment.

Adaptive Accommodation Control Method for Complex Assembly

Robotic systems have been used to automate assembly tasks in manufacturing and in teleoperation. Conventional robotic systems, however, have been ineffective in controlling contact force in multiple contact states of complex assemblythat involves interactions between complex-shaped parts. Unlike robots, humans excel at complex assembly tasks by utilizing their intrinsic impedance, forces and torque sensation, and tactile contact clues. By examining the human behavior in assembling complex parts, this study proposes a novel geometry-independent control method for robotic assembly using adaptive accommodation (or damping) algorithm. Two important conditions for complex assembly, target approachability and bounded contact force, can be met by the proposed control scheme. It generates target approachable motion that leads the object to move closer to a desired target position, while contact force is kept under a predetermined value. Experimental results from complex assembly tests have confirmed the feasibility and applicability of the proposed method.