Swing-up and stability control of Wheeled Acrobot (WAcrobot)

In this paper the Wheeled Acrobot (WAcrobot), a novel mechanical system consisting of an underactuated double inverted pendulum robot (Acrobot) equipped with actuated wheels, is described. This underactuated and highly nonlinear system has potential applications in mobile manipulators and leg-wheeled robots. It is also a testbed for researchers studying advanced methodologies in nonlinear control. The control system for swing-up of the WAcrobot based on collocated or non-collocated feedback linearisation to linearise the active or passive Degree Of Freedom (DOF) followed by Linear Quadratic Regulator (LQR) to stabilise the robot is discussed. The effectiveness of the proposed scheme is validated with numerical simulation. The numerical results are visualised by graphical simulation to demonstrate the correlation between the numerical results and the WAcrobot physical response.

An investigation into the perceived quality of communications in dispersed construction project teams

Construction project teams are increasingly operating in dispersed arrangements in which communications predominantly take place via information communication technology (ICT) with a dose of face-to-face interactions. However, a review of literature reflects a scarcity of research on how shifting to dispersed teams affects the perceived quality of communications in construction project teams. The present study attempts to address such a gap in the body of knowledge. To this end, 12 major indicators of quality of communications were identified through a review of literature. This was followed by conducting 17 semi-structured interviews with experts in the industry to customize the indicators for the construction context. Based on the identified indicators, a questionnaire survey was designed for elucidating the perceptions of construction practitioners about changes in quality of communications in dispersed teams in comparison to fully collocated ones. Drawing upon the data collated from 285 duly completed questionnaires, confirmatory factor analysis (CFA) was deployed to define the major areas of change in quality of communications in dispersed teams as perceived by the respondents. The findings showed that shifting towards dispersed working results in a change in perceived quality of communications in ten areas mainly reduction in completeness and reliability of communications. The present study contributes to the field by providing a list of indicators for assessing the quality of communications for construction project teams. Additionally, the findings provide an illuminating insight into the primary changes in perceived quality of communications in disperse team arrangements.

Factors affecting perceived level of virtuality in hybrid construction project teams (HCPTs) : a qualitative study

Purpose-Deploying hybrid construction project teams (HCPTs) in which the common pattern of interactions is a blend of face-to-face and virtual communications has been increasingly gaining momentum in the construction context. Evidence has demonstrated that effectiveness of HCPTs is affected by a perceived level of virtuality, i.e. the perception of distance and boundaries between members where teams shift towards working virtually as opposed to purely collocated teams. This study aims to provide an integrated model of the factors affecting perceived virtuality in HCPTs, to address the conspicuous absence of studies on virtuality in the construction context. Design/methodology/approach-An a priori list of factors extracted from existing literature on virtuality was subjected to the scrutiny of 17 experts with experiences of working in HCPTs through semi-structured interviews. Nvivo 10 was deployed for analysing the interview transcripts. Findings-The fndings outline the factors affecting virtuality in HCPTs and map the patterns of their associations as an integrated model. This leads to discovering a number of novel factors, which exert moderating impacts upon perceived virtuality in HCPTs. Practical implications-The fndings assist managers and practitioners dealing with any form of HCPTs (including building information modelling-based networks and distributed design teams) in identifying the variables manipulating the effectiveness of their teams. This enables them of designing more effective team arrangements. Originality/value-As the frst empirical study on virtuality in the construction context, this paper contributes to the sphere by conceptualising and contextualising the concept of virtuality in the construction industry. The study presents a new typology for the factors affecting perceived virtuality by categorising them into predictors and moderators.