Design And Implementation Of Semiautonomous Navigation Wheelchair System

With the aging of Chinese population,the number of elderly people with disabilities is increasing,whose transfer outside become a focused social problem.For wheelchair users,they are often the elderly with weak control ability,and it is still difficult for them to operate a wheelchair not smart enough currently and the learning is also hard.The designed and implemented navigation wheelchair system in this thesis can not only carry out autonomous positioning and route planning,but also avoid obstacles automatically,which greatly reduces the operation difficulty and lowers use threshold for elderly users.Based on the highly popularity of smart phones,the well performance of GPS positioning service within smart phone and the consideration of cost,this thesis designs and implements a semi-autonomous navigation wheelchair system based on android system.Main research contents are as follows:The hardware system is designed,and in each part of the circuit carries out modular design to reduce the cost and be easier for mass production,including the designs of main control module,rocker control interface module and ranging module.The functions to control wheelchair's movement,collect its self-movement information and communicate with the mobile phone in real-time have been implemented.In the positioning navigation design,this thesis researches the multi-sensor fusion technology,and the EKF algorithms of IMU and GPS are designed and implemented,realizing the data fusion and making a more accurate and reliable calculation of the wheelchair's motion posture information.The design of route planning method and the related algorithms is finished,local route planning is the main.The local route planning is to detect road edge mainly through the ranging sensor,and performs local drive according to the habit of driving along the right side.The sensor installation angle has been optimized,making the ranging sensor in the upper-right direction installed at an oblique angle to anticipate the next road condition so as to calculate the wheelchair's adjustment angle in advance.In the automatic obstacle avoidance design,the traditional artificial potential field method is optimized by introducing a new road potential field,thus improving the condition that the traditional algorithm is easy to fall into local minimum trap.In this thesis,an superior design is carried out on the introduced potential field,which means attraction or repulsion are set respectively based on the distance between the wheelchair to the right side of the road to guarantee a stably safety distance from a wheelchair to the road edge.To ensure the safety,this wheelchair is used in a car-free neighborhood,campus or park.Experiments are carried out in the campus environment in this paper and the experimental results show that the safety and practicability of the whole system can meet the requirements of semi-autonomous navigation.