Investigation of the Light Load in Propelling a Handcart on Various Road Resistances

Abstract

Propelling handcart tasks, such as pushing a wheelchair with an occupant or a handcart with heavy objects are well seen and met in our daily life and occupational works. Office workers and attendants in propelling wheelchairs are physically weaker than workers in industries. Also, aged persons propelling wheelchairs for aged spouses increase in recent aged society in advanced industrialized countries around the world. In this paper, we proposed the linear signal model of worker-cart system based on steady propelling state, and produced the experimental device for investigating the propelling activity in daily life. We analyzed the mechanism of the steady propelling behavior at steady state with the model and device. From experimental results with three subjects in his 20s, we found followings; The proposed model is useful in walking speed 1km/h above. Maximum estimated forces by single leg is around 50N against maximum road resistance, and the force decreases proportionally in walking speed 1km/h above against the decrease of the resistance. Also, autonomous natural pushing force in maximum mechanical power 25-40W, are carried out under exercising heart ratio (EHR) 30%, which shows light load activity to be able to continue over 20min.

Assisting control for attendant propelled wheelchair based on force velocity relationship

“…This is because the FV relationship for 15 min in the previous treadmill study [9] shows half the FV relationship than found in this study. From comparison with previous results, we employed a 30% FV relationship as the assisting boundary.…”

“…The force velocity relationship is well used to evaluate individual exercising performance, especially cycling [7,8]. We measured steady force velocity performance of attendant propelling on a motorised treadmill [9].…”

Powered attendant-propelled wheelchair with assist-as-needed control based on individual physical capabilities

“…An attendant voluntarily adjusts the performance of pushing force with walking and necessary blood flow to muscles changes EHR. Both pushing force and walking speed affect individual EHR level, and pushing force monotonically decreases with the increase of walking speed at the same EHR level (Suzuki et al, 2009). Any voluntary combination of pushing force and walking speed on a line needs the same EHR level.…”

“…The basic design of the APW is similar with self-propelled wheelchairs having two front casters and rear wheels, but doesn't have any hand rims in rear wheels, which is about a half size in common self-propelled wheelchair cases. The attendant has to provide all required physical strength to propel the APW with the occupant on various environmental terrains against resistance load (Abel and Frank, 1991b, Suzuki et al, 2009. The weight of the APW increases propelling load as increased normal forces distributed to two casters and two rear wheels enlarge total rolling resistance of the APW (van der Woulde 2003).…”

“…Our novel proposed assist-as-needed control paradigm, force velocity assist control (FVAC), employed individual force velocity relationship of pushing with walking under light hardness as assist boundary, which defined attendant's maximum performance without assisting. The force velocity relationship is well used to evaluate individual exercising performance, especially cycling (Vandewalle, 1987 andSargeant, 1994), and we investigated force velocity relationship in attendant pushing on treadmill (Suzuki et al, 2009) and on the ground (Suzuki et al, 2015). This study is aimed at investigating the performance of our proposed FVAC on flat level surface and longitudinal slopes, with three participants, to validate two points; 1) Operation of the FVAC, 2) FVAC performance on low and high load in terms of pushing and assisting forces and mechanical power, compared with the PAC.…”