Simplified CAD model of a person for the simulation of their movements

Currently, several computer programs evaluate the ergonomics of products or measure the physical effort a person must make in a particular task, either at her job, at home, or as a mechanical or electronic machine user. However, these computer programs are expensive and sometimes need to be installed with another program to run within them and share resources such as solid modeling, mass calculation, drawing generation, and finite element analysis.This article aims to define a simplified person model that can be used in different computer programs pointed at the academic community and available with student licenses. These models will simulate the mechanisms of the devices older adults and people with special needs use for their training or recovery, making it possible to calculate the kinematics involved in using these appliances.This work also shows the type of kinematic constraints that must be defined so that the simplified model of a person can move. Each set of kinematic constraints will simulate a specific movement; the more constraints used, the better the representation of the natural movement of a person. Subsequently, with the simplified person model, devices aimed at older adults and people with special needs can be designed and evaluated and used in various computer programs with licenses for students.The methodology consists of initially defining a first simplified model of a person, as essential as possible, to define the kinematic restrictions to simulate their movements. Subsequently, a case study is used to evaluate the movements transmitted from an elliptical machine toward the person. Finally, a kinematic inversion is carried out to analyze the movements transmitted from the person to the elliptical machine.At the beginning of this work, a review of the leading computer programs that evaluate a person's ergonomics is made. Then the procedure used to define the simplified person model with its kinematic constraints is shown. Subsequently, through the case study, movements transmitted from the person to the case study and from the case study to the person are evaluated. At the end, the results are presented, as well as future work and conclusions.