Swing control for a three-link brachiation robot based on sliding-mode control on irregularly distributed bars

The bionic-gibbon robot is a popular bionic robot. The bionic-gibbon robot can imitate a gibbon in completing brachiation motion between branches. With nonlinear and underactuated properties, the robot has important research value. This paper designs a type of bionic-gibbon robot with three links and two grippers. To simplify the controller, a plane control model is proposed, and its dynamic model is established. The control strategy in this paper divides the brachiation motion into several processes: adjust posture, open the gripper, the swing process and close the gripper. Based on sliding-mode control (SMC), the control method for the swing process is designed. The target position of the brachiation motion is set as the origin of the sliding-mode surface. In a finite time, the robot will reach the target position along the approach rate we adopt. In this way, the robot can complete the desired brachiation motion only by setting the position parameters of the target bar. We perform some simulations in ROS-Gazebo. The simulation results show that the bionic-gibbon robot can complete continuous brachiation motion on irregularly distributed bars. The sliding-mode control and the three-link structure significantly improve the robustness and swing efficiency of the bionic-gibbon robot.

An Indexing Method of Continuous Spatiotemporal Queries for Stream Data Processing Rules of Detected Target Objects

Real-time performance is important in rule-based continuous spatiotemporal query processing for risk analysis and decision making of target objects collected by sensors of combat vessels. The existing Rete algorithm, which creates a compiled node link structure for executing rules, is known to be the best. However, when a large number of rules are to be processed and the stream data to be performed are large, the Rete technique has an overhead of searching for rules to be bound. This paper proposes a hashing indexing technique for Rete nodes to the overhead of searching for spatiotemporal condition rules that must be bound when rules are expressed in a node link structure. A performance comparison evaluation experiment was conducted with Drool, which implemented the Rete method, and the method that implemented the hash index method presented in this paper. For performance measurement, processing time was measured for the change in the number of rules, the change in the number of objects, and the distribution of objects. The hash index method presented in this paper improved performance by at least 18% compared to Drool.

Vibration Characteristics of an Industrial-Scale Flip-Flow Screen with Crank-Link Structure and Parameters Optimization

Flip-flow screens are increasingly used in the processing of fine wet coal. In this work, the vibration characteristics of an industrial-scale flip-flow screen with crank-link structure (FFSCLS) were investigated theoretically and experimentally. An improved kinematic model of FFSCLS was proposed and experiments are carried out to verify the reasonability. The effects of the key parameters of the eccentricity of the crankshaft, the rotational speed of the crankshaft, and the tension length of the screen surface on the vibration characteristics of the screen were investigated parametrically. The results show that the kinematic model can describe the vibration characteristics of screen perfectly with the maximum error between the theoretical and experimental results being within 6.96%. Moreover, the key parameters of the eccentricity of the crankshaft, the rotational speed of the crankshaft, and the tension length of the screen surface have significant effects on the vibrations of the screen body and screen surface. These parameters should be optimized to achieve maximum screening performance of the FFSCLS. This work should be useful for optimal design and efficient operation of the flip-flow screen.

Web Page Ranking using Web Mining Techniques: A comprehensive survey

<div>Purpose: Due to the exponential growth of internet users and internet traffic, information seekers are highly dependent upon search engines to extract relevant information. Due to the accessibility of a large amount of textual, audio, video etc. contents, the responsibility of search engines has increased.</div><div>Design/methodology/approach: The search engine provides relevant information to internet users concerning to their query; based on content, link structure etc. However, it does not provide the guarantee of the correctness of the information. The performance of a search engine is highly dependent upon the ranking module. The performance of the ranking module is dependent upon the link structure of web pages, which analyse through Web structure mining (WSM) and their content, which analyses through Web content mining (WCM). Web mining plays an important role in computing the rank of web pages.</div><div>Findings: In this article, web mining types, techniques, tools, algorithms and their challenges are presented. Further, it provides a critical comprehensive survey for the researchers by presenting different features of web pages, which are important to check the quality of web pages.</div><div>Originality: In this work, authors presented different approaches/techniques, algorithms and evaluation approaches in previous researches and identified some critical issues in page ranking & web mining, which provide future directions for the researchers, working in the area.</div>

Web Page Ranking using Web Mining Techniques: A comprehensive survey

<div>Purpose: Due to the exponential growth of internet users and internet traffic, information seekers are highly dependent upon search engines to extract relevant information. Due to the accessibility of a large amount of textual, audio, video etc. contents, the responsibility of search engines has increased.</div><div>Design/methodology/approach: The search engine provides relevant information to internet users concerning to their query; based on content, link structure etc. However, it does not provide the guarantee of the correctness of the information. The performance of a search engine is highly dependent upon the ranking module. The performance of the ranking module is dependent upon the link structure of web pages, which analyse through Web structure mining (WSM) and their content, which analyses through Web content mining (WCM). Web mining plays an important role in computing the rank of web pages.</div><div>Findings: In this article, web mining types, techniques, tools, algorithms and their challenges are presented. Further, it provides a critical comprehensive survey for the researchers by presenting different features of web pages, which are important to check the quality of web pages.</div><div>Originality: In this work, authors presented different approaches/techniques, algorithms and evaluation approaches in previous researches and identified some critical issues in page ranking & web mining, which provide future directions for the researchers, working in the area.</div>

Dual Channel Among Task and Contribution on OSS Communities: An Empirical Study

Open Source Software (OSS) community has attracted a large number of distributed developers to work together, e.g. reporting and discussing issues as well as submitting and reviewing code. OSS developers create links among development units (e.g. issues and pull requests in GitHub), share their opinions and promote the resolution of development units. Although previous work has examined the role of links in recommending high-priority tasks and reducing resource waste, the understanding of the actual usage of links in practice is still limited. To address the research gap, we conduct an empirical study based on the 5W1H model and data mining from five popular OSS projects on GitHub. We find that links originating from a PR are more common than the other three types of links, and links are more frequently created in Documentation. We also find that average duration between development units’ create time in a link is half a year. We observed that link behaviors are very complex and the duration of link increases with the complexity of link structure. We also observe that the reasons of link are very different, especially in P–P and I–I. Finally, future works are discussed in conclusion.

FST-Convoy: A Leader Tracking Control of Vehicles Connected by Shape Sensor FST

This paper describes FST-Convoy, a leader tracking control system for vehicles using the shape sensor flexible sensor tube (FST). Among many methods of autonomous driving, follow-driving is one of them. Some of these have been put into practical use in a limited environment. Unfortunately, there are situations in which such sensors do not work well. One of these is underground. In the underground, GNSS signals do not reach vehicles, so they cannot obtain their positions. Therefore, we propose a new way to achieve follow-driving in such environments. We used the shape sensor, FST. The FST is a shape sensor with a serial link structure and many joints. It can measure its shape by solving its kinematics and determine the relative position of the start link to the end link. Therefore, we can measure the relative positions of vehicles that connected a leader and a follower using FST. We call this system FST-Convoy. We developed and verified the system using a platooning-driving experiment.

Barrier-Free Wheelchair with a Mechanical Transmission

Wheelchairs are an important means of transportation for the elderly and disabled. However, the movement of wheelchairs on long curbs and stairs is restricted. In this study, a wheelchair for climbing stairs was developed based on a mechanical transmission system that rotates the entire driving part through a link structure and an actuator to change the speed. The first mode drives the caterpillar, and the second mode drives the wheels. When driving on flat ground, it uses landing gears and wheels, and when climbing stairs, it uses the caterpillar; accordingly, a stable driving is possible. The stability of the transmission is confirmed through stress analysis. The method used in our study makes it is possible to manufacture lightweight wheelchairs because a single motor drives both the wheel and caterpillar through the transmission system.