Design And Research Of Assistive Toilet Products Based On "Sit-to-Stand"

The physical function of the elderly is weakened,and the normal sit-to-stand transition is not possible to be accomplished due to the lack of leg strength in toilet,which easily leads to dangerous accidents.Therefore,the design of toilet auxiliary products for the elderly has become a current research focus.The toilet seat is the part of the toilet auxiliary product,which directly contacts with the human body and is a key link in the design of the toilet auxiliary product.At present,the design of the toilet seat is mostly biased towards the modeling design while ignoring the comfort and safety.In addition,the study of the human sit-to-stand motion trajectory is a reference to guide the design of toilet auxiliary products.If the lifting trajectory of the toilet auxiliary product does not meet the human body’s natural sit-to-stand motion rules,and it will cause secondary damage to the human body.But many toilet auxiliary products are lack of in-depth research on the movement trajectory of sit-to-stand.In view of the above problems,this paper designs a toilet assistant sitting product to meet the needs of the elderly,and the product can improve the comfort and safety of the elderly in the toilet.The main research contents are as follows.Firstly,in order to design a comfortable and safe toilet seat,a comprehensive design method combining modeling design and finite element analysis was proposed.The design elements of the modeling are summed up by using Kansei Engineering,and eight modeling schemes of different seats are preliminarily designed.The semantic difference method was used to evaluate the aesthetic and perceptual intention of the preliminary design scheme,and four types of beautiful shapes are selected based on users’ subjective feelings.Then,four kinds of beautiful toilet seats are assembled with the standard human body model for finite element analysis to obtain the contact pressure between the human body and the toilet seat.The Analytic hierarchy process that bases on the aesthetic values and average pressures is used to integrally evaluate to have obtained the Scheme 5 is the best.Finally,the rationality of the optimal scheme design of the toilet seat is verified by experiments.Secondly,in order to improve the safety,stability and comfort of the elderly during the process of sit-to-stand transition in the toilet,in-depth research has been conducted on the human sit-to-stand transition movement.The Inertial Measurement Unit（IMU）was used to perform sit-to-stand transition experiment on healthy subjects with different postures to obtain the variation rules of knee and hip joints,then the obtained uniform sit-to-stand transition motion trajectory and the existing sit-to-stand transition motion trajectory studied by Li Jin were matched with the optimal designed toilet seat,respectively,and were conducted analysis of finite element dynamic pressure with sitting incline angle of 0°,10°,20°,30°,40°,the results showed the average pressure of the sit-to-stand transition trajectory studied in this paper are lower than the existing research of Li Jin at the same sitting incline posture,which demonstrated the sit-to-stand transition trajectory studied in this paper is more in accordance with the human body’s natural sit-to-stand transition rules.Finally,according to its using environment,principle of ergonomics,design aesthetics,color and material,the lifting structure and overall appearance of the toilet auxiliary products are divergently designed based on the optimal design scheme of the toilet seat and the movement trajectory that meets to the human body’s natural sit-to-stand transition,and the overall scheme that ultimately meets the needs of users was selected by using fuzzy evaluation method.Then the practice has proved that it is feasible to introduce Kansei Engineering,design aesthetics,finite element and motion trajectory experiments into the design of the toilet auxiliary products,which has a positive effect on the design of congeneric products,and also provide a scientific design guidance for the development of relative product.