Design And Analysis Of Leg-wheel Stair-climbing Electric Wheelchair

Wheelchairs are the first choice of the transportation for lower limb disabled people like the elderly, which play an irreplaceable role in raising living standards of this special crowd. However, neither manual wheelchair nor ordinary electric wheelchair has the function of stairs-climbing or obstacle-crossing, which limits activities of the users. Aiming at this problem, a kind of leg-wheel stair-climbing electric Wheelchair is proposed in this paper. This wheelchair moves with wheels when the ground is flat, and walks with legs when climbing the stairs.At first, mechanical structure of the leg-wheel stair-climbing electric Wheelchair is designed and the size of the chair is planned based on the theory of ergonomics. The wheelchair can be divided into three mobile modules. And the adjustment of the center of gravity is proposed. The seat is fixed on the first mobile module, making the center of gravity control system a part of the mobile system, which reduces the difficulty in controlling.Secondly, the path planning, including stair-climbing gait and turning path on plat, is completed. The way of the cooperation which consists of the extension and contraction of the legs and movement among the mobile modules, is designed. And the movement of the leg is analyzed as an example. A kinematic equation is established based on the movement analysis of the wheels under the legs, which establishes the mapping relationship between the movement of the wheelchair and the motors.The kinematic and dynamic of the wheelchair model is analyzed. Direct kinematic Problems is solved by using coordinate transformation method, thus dynamics equation is obtained, which proves that the stair-climbing gait is feasible, and also provides the theoretical basis and necessary data for it, as well as the following design of the control system. And the dynamics of wheelchair model is analyzed through Lagrange method, which provide theoretical basis for motor choosing, motion simulation and motion control. The simplified model of the wheelchair is built in ADAMS virtual prototype software for the motion simulation analysis, through which obtains the displacement curve of legs and the center of mass, as well as the force curves of legs. The result proves that the method of model building and the stair-climbing gait are correct.At last, an experiment for measuring the parameters of the stairs is designed. A hardware experimental platform is set up based on the principle of the measurement and the software system is designed based on Lab VIEW. Meanwhile, the experimental data processing is completed in MATLAB. And the results show that the experimental principle is correct, and the data processing method is feasible which can satisfy the actual needs.