2006 Volume 18 Pages 89-100
The main object of this study is to establish the measurement and analysis of three dimensional human movements for designing wheelchairs. First, we have developed an instrument system, which can be attached to several types of wheelchair, to measure the three dimensional displacement/orientation of upper limb and force/moment at the contact point between the hand rim and the user's hand. The measurement values of each user are used to calculate the dynamic properties of the user function. Second, we have defined a new dynamical manipulability using an ellipsoid so as to find out the best direction of driving force at each instance in the driving cycle. Kinematic relationship between the generated tensions of muscles and the effective force for wheelchair propulsion can be seen with the ellipsoids along the trajectory of the user's hand. Finally, a new method has been proposed to find the optimal position of the seat or the optimal driving form based on the movement of the upper limb of the user, experimental data of generated force and moment, and a rigid link model for the upper limb and body. We have given an example to prove that the designed wheelchair effectively reduces the user's mechanical work by as much as 20%. The results of this study can serve as a platform to design the optimal wheelchair for each individual user.
