Search results

This study aims to design a controller which can improve the end-effector low-frequency chattering resulting from the measurement noise and the time delay in the on-orbit tasks. The rendezvous point will move along the rendezvous ring owing to the error of the camera, and the manipulators’ collision need be avoided. In addition, owing to the dynamics coupling, the manipulators’ motion will disturb the spacecraft, and the low tracking accuracy of the end-effector needs to be improved.

This paper proposes a minimum disturbance controller based on the synchronous and adaptive acceleration planning to improve the tracking error and the disturbance energy. The synchronous and adaptive acceleration planning method plans the optimal rendezvous point and designs synchronous approaching method and provides an estimation method of the rendezvous point acceleration. A minimum disturbance controller is designed based on the energy conservation to optimize the disturbance resulting from the manipulator’s motion.

The acceleration planning method avoids the collision of two end-effectors and reduces the error caused by the low-frequency chattering. The minimum disturbance controller minimizes the disturbance energy of the manipulators’ motion transferred to the spacecraft. Experiment results show that the proposed method improves the low-frequency chattering, and the average position tracking error reduces by 30%, and disturbance energy reduces by 30% at least. In addition, it has good performances in the synchronous motion and adaptive tracking.

Given the immeasurability of the target satellite acceleration in space, this paper proposes an estimation method of the acceleration. This paper proposes a synchronous and adaptive acceleration planning method. In addition, the rendezvous points are optimized to avoid the two end-effectors collisions. By the energy conservation, the minimum disturbance controller is designed to ensure a satisfying tracking error and reduce the disturbance energy resulting from the manipulators’ motion.

The purpose of this paper is to propose a smooth double-spline interpolation method for six-degree-of-freedom rotational robot manipulators, achieving the global C2 continuity of the robot trajectory.

This paper presents a smooth double-spline interpolation method, achieving the global C2 continuity of the robot trajectory. The tool center positions and quaternion orientations are first fitted by a cubic B-spline curve and a quartic-polynomial-based quaternion spline curve, respectively. Then, a parameter synchronization model is proposed to realize the synchronous and smooth movement of the robot along the double spline curves. Finally, an extra u-s function is used to record the relationship between the B-spline parameter and its arc length parameter, which may reduce the feed rate fluctuation in interpolation. The seven segments jerk-limited feed rate profile is used to generate motion commands for algorithm validation.

The simulation and experimental results demonstrate that the proposed method is effective and can generate the global C2-continuity robot trajectory.

The main contributions of this paper are as follows: guarantee the C2 continuity of the position path and quaternion orientation path simultaneously; provide a parameter synchronization model to realize the synchronous and smooth movement of the robot along the double spline curves; and add an extra u-s function to realize arc length parameterization of the B-spline path, which may reduce the feed rate fluctuation in interpolation.

This paper seeks to present an approach to the improvement of the risk analysis of construction projects by linking risk analysis to the potential variances in time and cost performance of endogenous variables. This link is synchronous, such that changes in either the cost or time schedule variables are uniquely modelled to the overall time and cost profile of a project.

The presented approach is based on synchronous time and cost scheduling, simulation and the methodology presented here develops technical indicators on the basis of virtual management momentum (VMM).

The paper shows a potential improvement to management decision making by the use of VMM. Senior management can test alternative strategies and develop probability matrices defining the potential results.

The current model simulates the impact of endogenous risks, and therefore by implication excludes all exogenous risks. This limitation can be removed by the introduction of other risk vectors, but is beyond the scope of the current research.

The mapping technique utilised to display these changes makes the appreciation of such impacts visually simple and is extremely effective in improving the management of endogenous project risk.

The study of family mobilities necessitates an examination of how practices are orchestrated in time as well as space. Conventional approaches to the study of family time use either quantitative analysis of time-use data or qualitative studies of time pressure and work/life balance. The limitation with these approaches is that they assume a rather static family structure that is dominated by parents with young children. Moreover, these studies do not capture the dualistic quality of time; that time constitutes and is a constituent of family life. In this chapter, I use one-day diaries on organising and experiencing time, collated as part of the UK Mass Observation Project in Autumn 2017, to interrogate the relationality of family time. The analysis examines how family practices maybe sequential, synchronous, planned or serendipitous and how these different temporalities permeate the busyness of time pressure. These one-day accounts confirm how time is experienced through and by family and intimate relationships.

This paper aims to present an investigation of the problems concerned with delivering a variety of differing change programmes in a logically structured, repeatable and measurable manner.

Case studies were conducted on a selection of significantly different manufacturing facility programmes at GKN Aerospace where the output was a generic model more explicit and illustrative than previous approaches taken at the company.

This paper supports the idea that a strategic and tactical planning process with transferable, common key issues, can be managed in an environment of rapid change. Furthermore, discreet tailoring of the model enables differentiation of each programme type to support a standardized, repeatable and synchronous approach to change management.

This was achieved through the compilation of a single change management process termed the “5 × 5 Model” incorporating a multi‐site working document containing quantifiable, value‐added activities.

The new model presented here has been developed from previous literature and tested in practice, but requires further application to validate its applicability in different industry sectors.

The purpose of this paper is to enhance the accuracy as well as efficiency of high-speed machining, avoid the speed fluctuation caused by acceleration/deceleration (ACC/DEC) and increase the smoothness of feedrate in continuous corners or curves machining. The Hbot kinematic system was analyzed and combined with fused deposition modeling-based (FDM) additive manufacturing (AM) technology. Then a real-time adaptive look-ahead speed control algorithm was proposed.

To validate the performance of Hbot kinematic system and the proposed speed control algorithm, the positioning accuracy of Hbot and cross structure was compared. Also, the experimental verification was conducted among FDM based 3-D printer with cross structure as well as open source speed control algorithm (FDM with cross-OS), cross structure and the proposed speed control algorithm (FDM with cross-PS) and Hbot structure, as well as the proposed speed control algorithm (FDM with Hbot-PS), respectively.

The results indicate that the Hbot kinematic system leads to the high stability of positioning accuracy due to the small motion inertia. Furthermore, the experimental verification shows that the efficiency, printing precision and surface finish of models for FDM with Hbot-PS are obviously higher than that for FDM with cross-PS as well as FDM with cross-OS, while FDM with cross-OS shows the worst performance. The contribution of Hbot kinematic system and the proposed speed control algorithm to FDM based AM technology was validated by this work.

The Hbot kinematic system and proposed speed control algorithm have the important implication of improving the accuracy of FDM machines, especially in the low-price range segment. Also, this work can help future system developers show a possible way of tackling the motion inertia problem.

The study of Hbot kinematic system and proposed algorithm are expected to advise the current research for improving the accuracy as well as the efficiency of FDM-based AM technology.

This chapter highlights our survey that identifies faculty recommendations for incorporating emerging digital technologies to deliver eLearning content in online courses that help students learn more effectively. Results from the survey, which includes a sample of 478 online faculty at two higher education institutions, are presented.

In the findings of the survey, respondents identified several instructional technologies such as augmented reality (AR), virtual reality (VR), mixed reality (MR), and artificial intelligence (AI) as being on the cusp of changing learner engagement options and could soon become standard tools for the online course environment. While respondents predict an acceleration of new technology activity, they also caution that these technologies need a strong pedagogical foundation to match student needs and generate new use-learning real case scenarios.

This sentiment implies a more systematic approach to problem-solving that follows a process of identifying and refining multiple options to determine best practices for faculty preparation and staff development. The results of the survey included in this chapter are a directional means to help instructors and course designers explain what is relevant and exciting about techniques that can be employed and identify and use the emerging technological tools that enhance the delivery of instruction while meeting the ever-changing and dynamic needs of today’s learners.

Supply chain management is a major issue in many industries as firms realize the importance of creating an integrated relationship with their suppliers and customers. Managing the supply chain has become a way of improving competitiveness by reducing uncertainty and enhancing customer service. This paper analyzes various issues important to supply chain management and provides broader awareness of supply chain principles and concepts. The role of planning and coordination in complex integrated systems and information technology to synchronize the supply chain is described in a framework that creates the appropriate structure and installs proper controls in the enterprise and other constituents in the chain.

This study aims to present an automated guided logistics robot mainly designed for pallet transportation. Logistics robot is compactly designed. It could pick up the pallet precisely and transport the pallet up to 1,000 kg automatically in the warehouse. It could move freely in all directions without turning the chassis. It could work without any additional infrastructure based on laser navigation system proposed in this work.

Logistics robot should be able to move underneath and lift up the pallet accurately. Logistics robot mainly consists of two sub-robots, like two forks of the forklift. Each sub-robot has front and rear driving units. A new compact driving unit is compactly designed as a key component to ensure access to the narrow free entry of the pallet. Besides synchronous motions in all directions, the two sub-robots should also perform synchronous lifting up and laying down the pallet. Logistics robot uses a front laser to detect obstacles and locate itself using on-board navigation system. A rear laser is used to recognize and guide the sub-robots to pick up the pallet precisely within ± 5mm/1o in x-/yaw direction. Path planning algorithm under different constraints is proposed for logistics robot to obey the traffic rules of pallet logistics.

Compared with the traditional forklift vehicles, logistics robot has the advantages of more compact structure and higher expandability. It can realize the omnidirectional movement flexibly without turning the chassis and take zero-radius turn by controlling compact driving units synchronously. Logistics robot can move collision-free into any pallet that has not been precisely placed. It can plan the paths for returning to charge station and charge automatically. So it can work uninterruptedly for 7 × 24 h. Path planning algorithm proposed can avoid traffic congestion and improve the passability of the narrow roads to improve logistics efficiencies. Logistics robot is quite suitable for the standardized logistics factory with small working space.

This is a new innovation for pallet transportation vehicle to improve logistics automation.

Multi‐arm, collaborative, synchronous robots are gaining acceptance in industry, because of the cycle time reduction, productivity increase, flexibility and quality gain, distributed control, layout design/simulation, and programming support robot manufacturers and system integrators can offer. On the negative side, when things go wrong such systems are more complex to recover, and maintain, than non‐networked and non‐distributed controlled individual robots. In this paper, we introduce some of the most important engineering, and technology management principles that collaborate robots and their users and should be kept in mind while developing such systems, and/or planning for such applications.