Analysis on the manual control characteristics of the human pilot during the operation of the powered wheelchair

The electrically powered wheelchair (EPW) is now recognized to be an indispensable tool for people with motor disabilities. However, using EPW in daily life might be a cause of danger because of the poor maneuverability of some commercially available EPW products. In order to ease the manipulating sensitivity and produce a pleasant and secure EPW, a model representing the operator's control ability while using the EPW is necessary when designing an embedded controller. This paper proposes a model which describes the control characteristics of the human operator while she/he is using an EPW. The proposed model is constructed based on, and coincides with, the pilot model which represents the control capability of the human operator while doing her/his accustomed tasks. The model should be called the error model of the EPW, control because it contains two errors to be stabilized for pleasant and secure operation of the EPW. In addition, the proposed model is an enhanced version of the pilot model in the sense that the effects of the environmental changes acting on the pilot are taken into account. Experimental results show the validity of the error model and indicate that an inappropriately designed EPW controller strictly deteriorates the manual control performance. The results obtained will serve as a good basis for the design of the EPW controller.