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The coupling impact of hybrid uncertain errors on the machine precision is complex, as a result of which the designing method with multiple independent error sources under uncertainties remains a challenge. For the purpose of precision improvement, this paper focuses on the robot design and aims to present an assembly precision design method based on uncertain hybrid tolerance allocation (UHTA), to improve the positioning precision of the mechanized robot, as well as realize high precision positioning within the workspace.

The fundamentals of the parallel mechanism are introduced first to implement concept design of a 3-R(4S) &3-SS parallel robot. The kinematic modeling of the robot is carried out, and the performance indexes of the robot are calculated via Jacobian matrix, on the basis of which, the 3D spatial overall workspace can be quantified and visualized, under the constraints of limited rod, to avoid the singular position. The error of the robot is described, and a probabilistic error model is hereby developed to classify the hybrid error sensitivity of each independent uncertain error source by Monte Carlo stochastic method. Most innovatively, a methodology called UHTA is proposed to optimize the robot precision, and the tolerance allocation approach is conducted to reduce the overall error amplitude and improve the robotized positioning precision, on the premise of not increasing assembly cost.

The proposed approach is validated by digital simulation of medical puncture robot. The experiment highlights the mathematical findings that the horizontal plane positioning error of the parallel robotic mechanism can be effectively reduced after using UHTA, and the average precision can be improved by up to 39.54%.

The originality lies in UHTA-based precision design method for parallel robots. The proposed method has widely expanding application scenarios in industrial robots, biomedical robots and other assembly automation fields.

Economic, flexible and efficient micro production needs new miniaturized automation equipment (desktop factories). Micro assembly processes make demands on precision of miniaturized robots used in desktop factories and the driving concepts, as well as miniaturized machine elements. The purpose of this paper is to investigate miniaturized drives using micro harmonic drive gears, which are promising driving concepts.

The analysis of the miniaturized precision robot Parvus (using micro harmonic drive gears) shows a good repeatability but also room for improvement concerning the path accuracy. Thereby the transmission error of the micro gears is identified as main disturbing influence concerning the robot's precision characteristics. Owing to the size reduction of the micro harmonic drive gear and the slightly different working principle compared to larger harmonic drive gears, the transmission error are more pronounced. Therefore, it is necessary to discuss approaches to compensate for this effect.

A very promising approach is the use of a simplified model of the kinematic error within the robot control to compensate for this disturbing effect. Measurement data of the transmission error is mathematically transformed into the frequency domain and filtered to the most important frequency modes of the function. These modes are used to build up a simplified mathematic model of the gear transmission error. A final test using this model as compensation function demonstrates that it is possible to reduce the transmission error of the micro gears by more than 50 percent.

The paper presents the first investigation into compensation of the transmission error of micro harmonic drive gears.

The purpose of this paper is to investigate the impact and techniques for mitigating the effects of web robots on usage statistics collected by Open Access (OA) institutional repositories (IRs).

A close review of the literature provides a comprehensive list of web robot detection techniques. Reviews of system documentation and open source code are carried out along with personal interviews to provide a comparison of the robot detection techniques used in the major IR platforms. An empirical test based on a simple random sample of downloads with 96.20 per cent certainty is undertaken to measure the accuracy of an IR’s web robot detection at a large Irish University.

While web robot detection is not ignored in IRs, there are areas where the two main systems could be improved. The technique tested here is found to have successfully detected 94.18 per cent of web robots visiting the site over a two-year period (recall), with a precision of 98.92 per cent. Due to the high level of robot activity in repositories, correctly labelling more robots has an exponential effect on the accuracy of usage statistics.

This study is performed on one repository using a single system. Future studies across multiple sites and platforms are needed to determine the accuracy of web robot detection in OA repositories generally.

This is the only study to date to have investigated web robot detection in IRs. It puts forward the first empirical benchmarking of accuracy in IR usage statistics.

The purpose of this paper is to propose going one step further in the simulation tools related to agriculture by integrating fleets of mobile robots for the execution of precision agriculture techniques. The proposed new simulation environment allows the user to define different mobiles robots and agricultural implements.

With this computational tool, the crop field, the fleet of robots and the different sensors and actuators that are incorporated into each robot can be configured by means of two interfaces: a configuration interface and a graphical interface, which interact with each other.

The system presented in this article unifies two very different areas – robotics and agriculture – to study and evaluate the implementation of precision agriculture techniques in a 3D virtual world. The simulation environment allows the users to represent realistic characteristics from a defined location and to model different variabilities that may affect the task performance accuracy of the fleet of robots.

This simulation environment, the first in incorporating fleets of heterogeneous mobile robots, provides realistic 3D simulations and videos, which grant a good representation and a better understanding of the robot labor in agricultural activities for researchers and engineers from different areas, who could be involved in the design and application of precision agriculture techniques. The environment is available at the internet, which is an added value for its expansion in the agriculture/robotics family.

High precision robots are often used for complex assembly or positioning tasks. One way to achieve high motion precision is to design mechanical systems based on flexure joints. Flexure joints (or flexures) utilize the elastic properties of matter, which brings avoidance of dry friction. Nanometer scale motions are then possible, without wear, mechanical play or particle emission. Leading to high performance systems in terms of dynamics, parallel kinematics are useful for high precision robot design. Two research projects are presented in this paper. The first one has already led to the realization of a micro electro‐discharge machine (μ‐EDM), and the second one’s goal is to generate a family of compact ultra‐high precision manipulators.

The industrial robot has high repeatability but low accuracy. With the industrial robot being widely used in complicated tasks, e.g. arc welding, offline programming and surgery, accuracy of the robot is more and more important. Robot calibration is an efficient way to improve the accuracy. Previous methods such as using coordinate measurement machines, laser trackers or cameras are limited by the cost, complex operation or the resolution. The purpose of this paper is to propose an approach and calibration equipment to address these issues.

The proposed method relies mainly upon a laser pointer attached on the end‐effector and single position‐sensitive devices (PSD) arbitrarily located on the workcell. The automated calibration procedure (about three minutes) involves aiming the laser lines loaded by the robot towards the center of the PSD surface from various robot positions and orientations. The localization is guaranteed by precise PSD feedback servoing control, which means physically the intersections of each pair of laser lines (virtual lines) are on the same point. Based on the untouched single‐point constraint, the robot joint offset calibration is implemented. Using the authors' proposed approach, a portable, low‐cost, battery‐powered, wireless and automated calibration system was implemented. Error analysis was conducted on the system.

The localization error of the developed calibration system is within 2 μm. The errors in joint space are magnified in PSD plane, and consequently the resolution in the joint space is improved. The standard deviation of the identified parameters was small (10‐2), indicating the stability of the calibration method. Both simulation and experimental results verify the feasibility of the proposed method and demonstrate the developed calibration system can identify joint offset with uncalibrated laser tool parameters.

The paper shows how a portable calibration system for joint offset of industrial robots was developed and how the goal of fast, automated, low‐cost, portable, and high precision calibration methods for joint offset was achieved.

The combination of the latest advancements in information and communication technologies with the latest developments in AutoID technologies, especially radio frequency identification (RFID), brings the possibility of high-resolution, item-level visibility of the entire supply chain. In the particular case of retail, visibility of both the stock count and item location in the shop floor is crucial not only for an effective management of the retail supply chain but also for physical retail stores to compete with online retailers. The purpose of this paper is to propose an autonomous robot that can perform stock-taking using RFID for item-level identification much more accurately and efficiently than the traditional method of using human operators with RFID handheld readers.

This work follows the design science research methodology. The paper highlights a required improvement for an RFID inventory robot. The design hypothesis leads to a novel algorithm. Then the cycle of development and evaluation is iterated several times. Finally, conclusions are derived and a new basis for further development is provided.

An autonomous robot for stock-taking is proven feasible. By applying a proper navigation strategy, coupled to the stream of identifications, the accuracy, precision, consistency and time to complete stock-taking are significantly better than doing the same task manually.

The main limitation of this work is the unavailability of data to analyze the actual impact on the correction of inventory record inaccuracy and its subsequent implications for the supply chain management. Nonetheless, it is shown that figures of actual stock-tacking procedures can be significantly improved.

This paper discloses the potential of deploying an inventory robot in the supply chain. The robot is called to be a key source of inventory data conforming supply chain management 4.0 and omnichannel retail.

Friction stir welding (FSW) is a novel method for joining materials without using consumables and without melting the materials. The purpose of this paper is to present the state of the art in robotic FSW and outline important steps for its implementation in industry and specifically the automotive industry.

This study focuses on the robot deflections during FSW, by relating process forces to the deviations from the programmed robot path and to the strength of the obtained joint. A robot adapted for the FSW process has been used in the experimental study. Two sensor‐based methods are implemented to determine path deviations during test runs and the resulting welds were examined with respect to tensile strength and path deviation.

It can be concluded that deflections must be compensated for in high strengths alloys. Several strategies can be applied including online sensing or compensation of the deflection in the robot program. The welding process was proven to be insensitive for small deviations and the presented path compensation methods are sufficient to obtain a strong and defect‐free welding joint.

This paper demonstrates the effect of FSW process forces on the robot, which is not found in literature. This is expected to contribute to the use of robots for FSW. The experiments were performed in a demonstrator facility which clearly showed the possibility of applying robotic FSW as a flexible industrial manufacturing process.