The Stability Analysis Of Intelligent Wheelchairs And The Terrain Recognition Of Pavement Point Cloud

Compared with ordinary electric wheelchairs,intelligent wheelchairs are safer,more efficient and convenient.Therefore,intelligent wheelchairs would be widely used by the elderly and the disabled in society.In recent years,the research on intelligent wheelchairs at home and abroad has made great progress,and has achieved rich results in human-computer interaction,obstacle avoidance and autonomous navigation.When the intelligent wheelchairs are used in complex terrains,such as slopes,stairs and ravines,it needs timely and accurate control.If there is no rapid and accurate recognition and judgment for the current situation,the wheelchair may lose control and become unstable,and maintaining the original state of motion may lead to serious consequences.This paper identifies different types of terrains by studying threedimensional point cloud and calculates the terrain parameters.This paper also conducts motion stability analysis according to its own motion states,making safe and efficient stability judgments.The main contributions of this paper are as follows:(1)Construction of an intelligent wheelchair hardware system.This paper retrofits an electric wheelchair,adding a motor driver,a rotary encoder,a motion solver module,a threedimensional laser point cloud scanning system and an industrial personal computer to the electric wheelchair.The retrofitted intelligent wheelchair is able to collect environmental threedimensional point cloud data and accurately control the running state of the intelligent wheelchair.It also has the functions of terrain recognition and stability judgment.This hardware experimental platform meets the research requirements of this paper.(2)A stability analysis method based on the stability cone model for smart wheelchairs.This paper deeply researches the motion stability of the intelligent wheelchair,and analyzes the sliding stability of the intelligent wheelchair to obtain its maximum slip angle parameter.When analyzing the tipping stability of the intelligent wheelchair with the stable cone model,its maximum tipping angle parameter is obtained.The two angle parameters give a complete overview of the instability of the wheelchair in life.Combining the two angle parameters,the stability judgment theory suitable for intelligent wheelchairs is summarized.This paper uses ADAMS software to build the models of the intelligent wheelchair and different types of terrains,and conducts motion simulation on terrains with different parameters to verify the applicability of the stability theory.(3)A road terrain recognition method based on geometric discontinuous points of line point clouds.Due to the fan-shaped distribution characteristics of point cloud data,the surface point cloud data is divided into ordered line point cloud discrete curves for recognition research so that the horizontal area can be better divided.The geometric characteristics of the line point clouds are obtained through the calculation of the discrete derivative to extract the discontinuous points of the line point clouds.By extracting the orderly discontinuous points in the point cloud data of different types,different types of terrains can be identified,and a method for identifying typical terrains is proposed.When extending the line point cloud recognition method to the surface point cloud recognition,the recognition error is effectively reduced by the method of neighborhood filtering.Through the recognition experiment of simulated and real terrains,it can be concluded that the terrain recognition method proposed in this paper is accurate.The intelligent wheelchair hardware system built in this paper has high reliability.The stability analysis method of the intelligent wheelchair can analyze the various stability of the intelligent wheelchairs.The road terrain recognition method is reliable and accurate.