Study On Design Of Electric Wheelchair Based On Driving Behavior Model

Age-related decline in physiological functions and limited mobility of the elderly,the disabled and the temporarily injured require the assistance of manual or electric wheelchairs to get around,with the total number estimated at over 65 million and growing at 5.9% per year.The use of electric wheelchairs as mobility aids has increased the freedom of movement of this group and increased social participation.However,driving a power wheelchair is a complex task that requires a certain level of cognitive and mobility skills,especially when the driver is faced with a complex and risky driving environment and driving task,which may lead to accidents due to the inability to make timely and correct decisions or reactions.Therefore,it is essential to study and design electric wheelchairs from the perspective of driving safety.Behavioural models of driving describe human cognitive,processing and manipulative behavioural processes in the study of transportation systems and have received much attention from scholars in the field of transport and vehicle engineering.Therefore,this thesis aims to understand the driving task and driving behaviour mechanism of electric wheelchairs from the driving behaviour model theory,and to guide the design practice of electric wheelchairs.To begin with,power wheelchair driving users,driving scenarios and driving tasks are identified and classified,and the SAFE task analysis model is used as the underlying logic to build a power wheelchair driving task analysis model.A typical power wheelchair obstacle avoidance driving task is selected as a case study for behavioural demand analysis,and key subtasks(judging the distance relationship between the wheelchair and the obstacle;judging whether the obstacle can be avoided)that affect the safety of the obstacle avoidance driving process and have a high level of complexity and risk are discovered,i.e.the judgement and decision-making process.Furthermore,the decision-making process of obstacle avoidance driving is understood in depth,and the decision-making process of obstacle avoidance driving is modelled from the concepts of "desired distance" and "desired safety distance".The driver’s decision-making process is then optimised from the perspective of driver assistance,and an obstacle-avoidance driving strategy is proposed that starts with obstacle recognition distance(i.e.recognising obstacle features and generating avoidance intentions)and is centred on desired safety distance(i.e.psychological safety distance),and the values of the two distance concepts are obtained through simulations to guide the subsequent design of the electric wheelchair.At the end,by sorting out and analysing other electric wheelchair driving tasks and combining the results of the analysis of the obstacle avoidance driving task,the electric wheelchair design objectives,strategies and principles are proposed and the electric wheelchair design practice is carried out.The design solution was evaluated using the constructed electric wheelchair task analysis model,and it was found that the complexity and risk level of the task was significantly reduced during the execution of the designed electric wheelchair,and the driver could complete the driving task more safely.The research constructs a task analysis model for electric wheelchairs,and analyses and understands the key sub-tasks of obstacle avoidance and proposes corresponding solution strategies,and finally proposes corresponding design strategies and design solutions.