Stiffness Design of Springs for a Screw Drive In-Pipe Robot to Pass through Curved Pipes and Vertical Straight Pipes

Various in-pipe robots used for inspection have been developed as a preventive measure against leakage. To expand the use of these robots in small pipelines, high environmental adaptability via a simple structure must be achieved. One solution, using the screw drive mechanism, has been focused on because it requires only one motor. However, the screw drive mechanism cannot achieve complex motion because of its 1-d.o.f. Therefore, existing screw drive in-pipe robots cannot pass through curved pipes with a small curvature radius. To overcome this problem, the kinematic analysis of the screw drive mechanism has been conducted on the basis of the basic principle of helical motion in curved pipes. From the analysis, the relationship among the spring stiffness, motor torque, robot length and static friction on the inner pipe wall is established for the design of stiffness of the supporting springs. The optimal spring stiffness is, thus, derived for the robot to pass through the curved pipe and to climb up in the vertical pipe. The experimental test has been used to verify the validity of the design.     

A study of an autonomous mobile robot in an outdoor environment

This paper describes an experimental study of the fabrication of micro-mechanisms on a silicon wafer. Planar process technology developed in the industry of CMOS LSI was employed. The structural material is CVD-polycrystalline silicon with a thickness of 2.5 μm and the sacrificial material is CVD-SiO₂ with a thickness of 1.0 μm. In the experimental study, micro-rotors with a shaft and a cap in an assembled form were fabricated on a silicon wafer. The self-alignment process gave a tolerance of 1.0 μm between the rotor and the shaft. The maximum rotation speed observed was 9 x 10⁴ rpm by blowing nitrogen gas.     

Development of a Positioning Technique for an Urban Area Using Omnidirectional Infrared Camera and Aerial Survey Data

This paper describes an outdoor positioning system for vehicles that can be applied to an urban canyon by using an omnidirectional infrared (IR) camera and a digital surface model (DSM). By means of omnidirectional IR images, this system enables robust positioning in urban areas where satellite invisibility caused by buildings hampers high-precision GPS measurements. The omnidirectional IR camera can generate IR images with an elevation of 20–70° for the surrounding area of 360°. The image captured by the camera is highly robust to light disturbances in the outdoor environment. Through the IR camera, the sky appears distinctively dark; this enables easy detection of the border between the sky and the buildings captured in white due to the difference in the atmospheric transmittance rate between visible light and IR rays. The omnidirectional image, which includes several building profiles, is compared with building-restoration images produced by the corresponding DSM in order to determine the self-position. Field experiments in an urban area show that the proposed outdoor positioning method is valid and effective, even if high-rise buildings cause satellite blockage that affects GPS measurements.     

Development of a steerable,wheel-type,in-pipe robot and its path planning

This paper presents the development of a steerable, wheel-type, in-pipe robot and its path planning. First, we show the construction of the robot and demonstrate its locomotion inside a pipe. The robot is composed of two wheel frames and an extendable arm which links the centers of the two wheel frames. The arm presses the frames against the interior wall of a pipe to support the robot. The wheels of the frames are steered independently so that the robot can turn within a small radius of rotation. Experimental results of the locomotion show that the steering control is effective for autonomous navigation to avoid obstacles and to enter the joint spaces of L- and T-shaped pipes. Generally, autonomous navigation is difficult for wheel-type robots because the steering angles required to travel along a desired path are not easily determined. In our previous work, the relationship between the steering angles and locomotion trajectories in a pipe has already been analyzed. Using this analysis, we propose the path planning in pipes.     

Real-time vision-based navigation and 3D depth estimation for an indoor autonomous mobile robot

A Transputer based artificial vision system that allows estimating a mobile robot's absolute position (navigation), it's motion parameters (egomotion) and a depth map of the sight of view is presented. Navigation is achieved by tracking expected features present in basic 3D CAD information of the environment. Egomotion and relative depth are estimated using optic flow calculated on closed contours of points in the scene presenting high spatio-temporal gradients and require no a-priori knowledge.     

Localization and guidance with an embarked camera on a mobile robot

In this paper, a new method using the Hough transform to correct the drift of the mobile robot CESA is presented. The corrections are made by direct observation. As an illustration, an algorithm implemented is detailed, and experiment results for CESA navigation in our laboratory's corridor and trajectory generation are given.     

Environmental map building for a mobile robot using infrared range-finder sensors

This paper presents a methodology for building a high-accuracy environmental map using a mobile robot. The design approach uses low-cost infrared range-finder sensors incorporating with neural networks. To enhance the map quality, the errors occurring from the sensors are corrected. The non-linearity error of the sensors is compensated using a backpropagation neural network and the random error of readings including the uncertainty of the environment is taken into a sensor model as a probabilistic approach. The map is represented by an occupancy grid framework and updated by the Bayesian estimation mechanism. The effectiveness of the proposed method is verified through a series of experiments.     

Position estimation of a mobile robot using images of a moving target in intelligent space with distributed sensors

Latest advances in hardware technology and state-of-the-art of mobile robots and artificial intelligence research can be employed to develop autonomous and distributed monitoring systems. A mobile service robot requires the perception of its present position to co-exist with humans and support humans effectively in populated environments. To realize this, a robot needs to keep track of relevant changes in the environment. This paper proposes localization of a mobile robot using images recognized by distributed intelligent networked devices in intelligent space (ISpace) in order to achieve these goals. This scheme combines data from the observed position, using dead-reckoning sensors, and the estimated position, using images of moving objects, such as a walking human captured by a camera system, to determine the location of a mobile robot. The moving object is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the ISpace. Using the a priori known path of a moving object and a perspective camera model, the geometric constraint equations that represent the relation between image frame coordinates for a moving object and the estimated robot's position are derived. The proposed method utilizes the error between the observed and estimated image coordinates to localize the mobile robot, and the Kalman filtering scheme is used for the estimation of the mobile robot location. The proposed approach is applied for a mobile robot in ISpace to show the reduction of uncertainty in determining the location of a mobile robot, and its performance is verified by computer simulation and experiment.     

Stability analysis of a vision-based control design for an autonomous mobile robot

We propose a simple control design allowing a mobile robot equipped with a camera to track a line on the ground. The control algorithm, as well as the image-processing algorithm, are very simple. We discuss the existence and the practical stability of an equilibrium trajectory of the robot when tracking a circular reference line. We then give a complementary analysis for arbitrary reference lines with bounded curvature. Experimental results confirm the theoretical analysis.     

Design and realization of a mobile wheelchair robot for all terrains

A novel design of a mobile wheelchair robot for all terrains, especially for staircases and inclines, is proposed. Toachieve the required locomotion, a pair of multi-limbed structures, comprised of a lift coxae, rotation femurs and support tibiae, are pivotally mounted on the opposite sides of the body and actuated to rotate through epicyclic gear trains. A dual-footing mode with a set of wheel and crawler tractors in each support tibia permits the locomotion mode depending on various terrains, and hence the mobile wheelchair robot can navigate on a flat surface, and climb up and down stairs or inclines with its body kept horizontal. The implemented design is verified experimentally using our first manufactured prototype mobile wheelchair robot and it is shown that it could be suitable for applications to wheelchairs or others.     

Path-following control of a mobile robot in the presence of actuator constraints

In this paper, we present a control law for a non-holonomic mobile robot that achieves path following. In the path-following problem, the objective is to control the angular velocity of the robot so that the robot tracks a given reference trajectory. In this paper, we propose a control law that achieves path following in the presence of a constraint on the angular velocity. By applying the proposed control law, the robot can track the reference trajectory even if the distance from the initial position of the robot and the reference trajectory is arbitrary large. Further, we extend the control law so that the linear velocity of the robot becomes small when the robot passes through corners. By using the control algorithm, we can prevent the angular velocity of the robot becoming extremely large when the robot passes through corners. Numerical examples are provided to illustrate the effectiveness of the proposed methods.     

Vision-based hybrid control scheme for autonomous parking of a mobile robot

This paper presents a novel vision-based hybrid controller for parking of mobile robots. Parking or docking is an essential behavioral unit for autonomous robots. The proposed hybrid controller comprises a discrete event controller to change the direction of travel and a pixel error-driven proportional controller to generate motion commands to achieve the continuous motion. At the velocity control level, the robot is driven using a built-in PID control system. The feedback system uses image plane measurements in pixel units to perform image-based visual servoing (IBVS). The constraints imposed due to the non-holonomic nature of the robot and the limited field of view of the camera are taken into account in designing the IBVS-based controller. The controller continuously compares the current view of the parking station against the reference view until the desired parking condition is achieved. A comprehensive analysis is provided to prove the convergence of the proposed method. Once the parking behavior is invoked, the robot has the ability to start from any arbitrary position to achieve successful parking given that initially the parking station is in the robot's field of view. As the method is purely based on vision the hybrid controller does not require any position information (or localization) of the robot. Using the Pioneer 3AT robot, several experiments are carried out to authenticate the method. The experimental system has the ability to achieve the parking state and align laterally within ±0.5 cm of the target pose.     

Fuzzy-differential evolution algorithm for planning time-optimal trajectories of a unicycle mobile robot on a predefined path

An evolutionary technique with a Fuzzy Inference System (FIS) is offered for planning time-optimal trajectories on a predefined Visibility Graph Method Dijkstra (VGM-D) path of a Nomad 200 mobile robot (MR). First of all, the segmented trajectory is generated by the VGM-D algorithm. Line and curve segments are the components of the trajectory. The number of intersections of the segmented VGM-D path determines the curve segments number. It is assumed that, at each curve segment, translation velocity v _t is taken as constant. The Differential Evolution (DE) algorithm finds v _t values of all the curve segments, which minimize the trajectory tracking time. Line segments lengths are used to calculate the constraints of the problem according to the Nomad 200's limitations on the translation velocity and acceleration/deceleration. The structures of the curve segments are modeled by FIS to decrease the DE's execution time. Another FIS model is used to define the upper bound of the translation velocities on the curve segments for the same purpose. Both FIS models are trained by the adapted-network-based fuzzy inference system (ANFIS). Experiments are successfully implemented on the Nomad 200 MR.     

Hybrid power supply for mobile robots

Service robots are frequently fitted with end-effecters, which require high energy, to achieve a specific task. Robots require high-power energy sources that can meet several goals simultaneously. Given the technology of today, a battery-driven robot cannot work for long on a single charge. Todevelop a new powerful battery technology may take many years of exhaustive research. In this paper, we present a dual-energized scheme called HYbrid POwer Supply (HYPOS) that integrates the function of batteries and a household electric system to supply a robot. This technique can be realized by existing technology and is applicable to a variety of indoor applications. The challenge of implementing the HYPOS system is to develop the outlet-connection procedures and to handle the electric cord to reduce movement disturbance. We report on the prototype robot and the experiments that illustrate the effectiveness and practicality of this proposed system. The result has shown that the HYPOS system can supply a robot consecutively for almost 2 h and its efficiency is 73.6%, while the efficiency of a lead-acid battery is only 38.5%.     

Development of the assistive mobile robot system: AMOS—to aid in the daily life of the physically handicapped

It can be exhausting, both physically and emotionally, to assist physically handicapped persons. Therefore, an assistive mobile system called AMOS (Assistive MObile robot System) has been developed to help alleviate this burden. The purpose of AMOS is to pick up and transport daily use objects, placing them in a designated indoor location semi-autonomously. AMOS consists of a self-contained mobile robot body, a user interface with a touch-panel and a computer network (Ethernet LAN, Internet). The user interacts with the mobile robot through a Web browser connected to a computer network, allowing for communication anytime, from anywhere and by anyone. This mode provides a simple way for communicating with and determining the status of the robot. Experiments were performed to verify the successful operation of AMOS. Although the system performed as designed, it would prove useful to the extend service area of the robot through communication mechanisms and the user interface.     

Development of a remote fault diagnosis system applicable to autonomous mobile robots

In this paper, the novel idea of using an autonomous mobile robot as a virtual local network is proposed as a system for the remote diagnosis of faults of a mobile robot. There are two primary points in this research. First, an objective of the research is to achieve a system with good expandability, i.e. one in which the diagnosis can be achieved whether there are many or few mobile robots to be diagnosed. To accomplish this goal by simply changing some system settings, a simple network management protocol (SNMP) structure is utilized. Within the developed diagnosis system, a mobile robot is taken as one of the management objects of the network management system (NMS). The SNMP, which is widely used in the NMS, is applied and adapted to the developed system as the communication protocol for exchanging diagnosis information. Moreover, by taking advantage of the active moving and sensing ability of autonomous mobile robots, an effective method of fault inference called a 'run-test' is discussed. By using this method, the accuracy of the diagnoses is improved. In the best-case scenario, the certainty of an accurate diagnosis increased from 20% (without using the 'run-test') to 93%. On the other hand, in some cases, the accuracy of the diagnosis results barely improved. On average, among the cases discussed in this paper, the accuracy of the diagnosis results improved about 2.1 times by the proposed method.     

Hardware implementation of neuromodulated neural network for a CPU-less autonomous mobile robot

In order to construct truly autonomous mobile robots, the concept of 'packaging' is indispensable; in packaging, all parts such as controllers, power systems and batteries should be embedded inside a finite physical space, i.e., a robot's body. Therefore, implementing a controller on hardware is one of the most promising ways, since this contributes to low power consumption, miniaturization, etc. Another crucial requirement in the field of autonomous mobile robots is robustness, i.e., autonomous mobile robots have to cope with their unpredictably changing environment in real-time. In this study, to meet these requirements, the concept of a dynamically rearrangeable electrical circuit (DREC) is proposed and we implement this onto field progammable gate arrays as physical electronic circuits by borrowing the idea from neuromodulation widely observed in biological nervous systems through the diffusion-reaction mechanism of neuromodulators. We developed the DREC for the peg-pushing task as a practical example. We confirmed that the physical DREC can successfully regulate the behavior according to the situation encountered by changing its properties in real-time.     

A method of measuring grinding points for a self-teaching grinding robot

This paper investigates human consciousness in comparison with a robots' internal state. On the basis of Husserlian phenomenology, nine requirements for a model of consciousness are proposed from different technical aspects: self, intentionality, anticipation, feedback process, certainty, embodiment, otherness, emotionality and chaos. Consciousness-based Architecture (CBA) for mobile robots was analyzed in comparison with the requirements proposed for a consciousness model. CBA, previously developed, is a software architecture with an evolutionary hierarchy of the relationship between consciousness and behavior. Experiments with this architecture loaded on two mobile robots explain the emergence of self, and some of the intentionality, anticipation, feedback process, embodiment and emotionality. Modification of CBA will be necessary to better explain the emergence of self in terms of the relationship between consciousness and behavior.