Key Engineering Materials Vol. 572

Abstract: Automation boosts competitiveness of manufacturing companies and is pervasive in modern industry. However, skilled manual labour is still used in a variety of complex tasks and is currently irreplaceable. A solution may lie in understanding the interactions between a human worker and the workpiece during a manufacturing task and digitising these interactions to potentially enable automation of the task. In this paper, a method to observe, record and digitise human-workpiece interactions using the Microsoft Kinect^TM is described. A manual threaded-fit assembly of a two-component pen housing is chosen. Essential information about the manual assembly is extracted from the recorded interaction data. The developed mechanism being markerless and unobtrusive is helpful in recording human-workpiece interactions in a factory without affecting normal operations.

Abstract: Modeling of drill pipe and optimization of its parameters are important in the design of drilling-sampling mechanism. The present study focused on the influence of drilling parameters on the excitement depth of Martian soil. A mathematical prediction model of the excitement depth of Martian soil was developed using response surface methodology (RSM). The effects of drill pipe parameters on the excitement depth of Martian soil were evaluated and optimum drill pipe parameters were determined using RSM. As a result, the predicted values and test values were quite close, which indicates that the developed model can be effectively used to predict the excitement depth of Martian soil. The given model could be utilized to select the level of drill pipe parameters. The efficiency of the sampling device will be improved by using this model.

Abstract: Based on the analysis of the methods for upper limb rehabilitation training, an anthropomorphic upper-limb exoskeleton was developed. Anatomical and physiological characteristics and upper limb joint ranges of motion are also considered. The rehabilitation robot is achieved by 4 single-axis revolute joints which are shoulder abduction-adduction (abd-add), shoulder flexion-extension (flx-ext), elbow flx-ext and wrist flx-ext. Kinematics and dynamics analysis of the rehabilitation robot are made. The passive rehabilitation mode and active rehabilitation mode are researched, and the result of experenment is shown that the robot can finish the rehabilitation task well.

Abstract: Aiming at the existing problems and shortcomings of current climbing robots which are short of migratory climbing, the climbing forms of robots are analyzed by means of theory of inventive problem solving (TRIZ). The contradictions of mobility and structural complexity are established and solved by combining with the TRIZ contradiction matrix. According to dynamic inventive theory, a new type of turnover climbing form is established. The new type of turnover climbing robot consists of the scalable body, the turnover arm installed on the body, the clamping claws and the controller installed on the turnover arm.

Abstract: A new type of clearing stump robot was developed to raise the efficiency of removing stump and reduce the damage of the ground surface in the cut over land. The robot mainly consists of a walking mechanism of a caterpillar excavator and a manipulator. It was controlled by a computer system based on the machine vision. The operating radius of the manipulator was 4-8 m, and the maximum stump cutting diameter was 0.55 m. The practical test shows that the robot can clear about 100 stumps per day (6 hours) compared to 45 similar stumps by hand-held implement. The efficiency of the robot is about 20-25 times than that of a worker. Especially, a hole of less than 1 m² is formed by the robot compared to 10 m² ground surface destroyed by employing another uprooter to clear a larch stump.

Abstract: Focusing on the longitudinal adaptability of a three-fuselage articulated with separated differential mechanism in rough terrain, the associated factor which could be a criterion for the judgment of longitudinal associated stability of mobile robot has been proposed, and the analysis results of the longitudinal associated stability under different situation have been obtained based on static stability theory of mobile robot.

Abstract: This paper deals with the walking stability analysis of a multi-legged crablike robot over slope using normalized energy stability margin (NESM) method in order to develop a common stabilization description method and achieve robust locomotion for the robot over rough terrains. The robot is simplified with its static stability being described by NESM. The mathematical model of static stability margin is built so as to carry out the simulation of walking stability over slope for the crablike robot that walks in double tetrapod gait. As a consequence, the relationship between stability margin and the height of the robots centroid, as well as its inclination relative to the ground is calculated by the stability criterion. The success and performance of the stability criterion proposed is verified through MATLAB simulation and real-world experiments using multi-legged crablike robot.

Abstract: A review of terramechanics terrain models and discuss on their application in link-terrain, wheel-terrain and tire-terrain interaction are taken. Three kinds of pressure–sinkage relationship proposed by Bekker and Reece are studied. The loading and unloading is introduced in the model. And the relationship between the maximum shear stress and applied normal pressure is derived. The link tractive effort and drawbar pull at a given slip of an assumed shape and mass are deduced. Also the link moves in two dimensions. At last, the relationship of terrain sinkage vs. time, terrain pressure vs. sinkage and drawbar pull vs. slip for the link-terrain interface are simulated. The simulation is in good agreement with that got by Bekker.

Abstract: In an efficient autonomous navigation and exploration, the robots should sense the environment as exactly as possible in real-time and act correctly on the basis of the acquired 3D data. Laser scanners have been used for the last 30 years for mobile robot navigation. However, they often did not enough speed, accuracy and field of view. In this paper we present the design and implementation of a scanning platform, which can be used for both outdoor and indoor mobile robot navigation and mapping. A 3D scanning platform based on a 2D laser rangefinder was designed in compact way for fast and accurate mapping with maximum field of view. The range finder is rotated around the vertical axis to extract the 3D indoor information. However, the scanner is designed to be placed in any direction on a mobile robot. The designed mechanism provides 360º degree horizontal by 240º degree vertical field of view. The maximum resolution is 0.36º degrees in elevation and variable in azimuth (0.1 degrees if scanning platform is set to complete a 360º degree rotation in 3.6 seconds). The proposed low cost compact design is tested by scanning a physical environment with known dimensions to show that it can be used as a precise and reliable high quality 3D sensor for autonomous mobile robots.

Abstract: The design of multi-robot cells for spot welding strictly influences the feasibility and complexity of the multi-robot motion planning. In comparison to existing literature, the proposed approach simultaneously addresses: (i) the design of multi-robot cells for spot welding; (ii) the allocation of the welding points to the robots on the basis of required cell cycle time. First, the algorithm selects one robot model and one robot fixturing structure. Second, the approach identifies free trajectories among welding points for each couple gun/position of the robot in the fixturing structure through probabilistic roadmaps (PRMs). Third, on the basis of the previous results, an innovative mathematical model selects and allocates the resources taking into account cell investment costs. Finally, the solutions that differ on robot model and robot fixturing structure are compared and the best solution is selected. A test case is provided to show the applicability of the approach.