The four-caster manually manoeuvred vehicle is a crucial device for goods movement and disability transport. While there are manual handling related health and safety concerns, no dynamical theoretical-empirical investigation exists. Theoretical examination demonstrates that, in loose terms, the motion resistance effects are affected by vehicle-frame translational velocity direction: the proportion of the moment effect to translational effect produced by motion resistance varies in a highly non-linear way depending on the vehicle-frame velocity direction. An empirical study is devised from the theory. As the intention was to investigate the presence of this phenomenon in real use, human operators were used: they made planar manoeuvres from static equilibrium with a self-selected load while attempting to maintain 11 (maximum) different centres of zero velocity which related to the velocity directions. Results demonstrate that (1) the proportion of moment motion resistance effect to translational motion resistance effect does vary and (2) it is motion resistance rather than inertial forces which are the first-order effect. These results are an essential first step in understanding the manoeuvring difficulties and health and safety issues which arise with these vehicles.

Motion resistance, handle forces, and translational acceleration of a four-caster manually manoeuvred vehicle (FMV) are examined at impending planar motion.FMV-wheel angular acceleration directions occur in polygon regions of the FMV-body translational acceleration. The mass centre force and torque, which balance motion resistance, using a Coulomb model, are non-linear and discontinuous functions of FMV-body acceleration.The transformation from mass centre force and torque to a dynamically equivalent handleforce measure is examined. A reference manoeuvre with a single set of caster orientations shows that FMV-body translational acceleration has a substantial effect on handle-force measure variation: an almost three-fold variation exists.The reference manoeuvre analysis is repeated with a representative sample of all caster orientations. The mean handle-force measure for this sample also shows a substantial handle-force measure variation, e.g. relatively high handle forces occur when the translational acceleration is directed as the impending change of FMV heading. This effect is independent of motion resistance values. As the handle forces required to balance motion resistance vary substantially depending on FMV-body translational acceleration, spatial constraints may have a substantial effect on handle forces. A relationship between handle forces and spatial constraints indicates that architectural planning has health and safety implications for the FMV operator.

Introduction: No research-based guidelines for adaptation planning for shower chairs and other vehicles with four casters exist, despite the manual handling nature of the manoeuvring task and the occupational therapy responsibility to plan for such vehicles. Method: It was determined from theory that changes in direction for these vehicles, such as from a passageway through a door, could be represented by 13 manoeuvres. Participants (n = 17) carried out 11 (maximum) manoeuvres based on this theory, each with the maximum comfortable occupant weight of their choice (weights represented the occupant). Findings: The maximum occupant weight selected as comfortable varied substantially between some of the 11 manoeuvres: there was a 100% difference between the lowest and highest weight selections. This indicated that four-caster vehicles (such as shower chairs) should not be treated as omni-directional for high occupant weights, or for floor materials with high motion resistance, because the manoeuvre direction substantially affects maximum comfortable weight selection. Conclusion: The manoeuvre with the highest weight selection is proposed as a guideline when manual handling concerns exist for these vehicles. The guideline can be modified for individual vehicles sizes, occupant and carer anatomy.

A novel method of identifying solutions for wheelchair access problems is presented. This method was developed in response to difficulties in identifying manoeuvring space requirements, particularly of wheelchair users with large or nonstandard wheelchairs. A simple theoretical model of wheelchair manoeuvring is used. This model allows scaled drawings of the wheelchair outline to be constrained on an adaptation plan, in a way that provides a useful representation of the space required during individual wheelchair manoeuvres. The method can allow speedier assessments, encourages the identification of novel and individual solutions and provides a simple visual account of decision making.