Modification of the Personal Cart and Its Control

This paper describes the modification of a computer-controlled walker, which is called the "Personal Cart" in order to actively support and stabilize the walking of healthy elderly persons by their selves. The cart system consists of computers and its controlling devices. The cart has four wheels, of which the left front wheel is driven by a DC motor. Expanding the space between the front wheels increases the stability of the cart. Furthermore, its operability was improved by the connection of an axis handle to the front wheels with a joint. The cart keeps the balance even if the weight of an operator is applied to the handle of the cart as the position of an operator is near the center of gravity of the triangle that is made between the front and rear wheels. The controller, which is synthesized based on a fuzzy theory, is set in the cart system to move while maintaining a certain distance between the operator and the cart. The membership functions of the proposed fuzzy controller are changed according to the angle of slopes, in order to improve its operability. The proposed system was confirmed to be useful in reducing the workload of the operator when walking on a slope with some baggage by experimentations.