A Fuzzy Control Based Stair-Climbing Service Robot

Recently, Taiwan and many developed countries have been experienced an emergence of growing aging population and decreasing working population and birth rate. The number of home-caring workers in need has surpassed that of available working force. Furthermore, the expense of home-caring elders will substantially increase. The employment of foreign workers is just a temporary solution. It is therefore necessary to develop a future substitute for the human work force. Home-caring robot is an excellent candidate capable of supporting such an aging society. Especially, the elders can control the robots directly to move up-and-down stairs for service. It is well-known that the most effective style of movement of a robot on a plane field is the wheel type. However, as obstacles and stairs exist, crawler-type and leg-type robots become better candidates for application. The robots of the stick type and the biped type are generally designed to carry elders up and down stairs. The former uses tires, rubber belts, and the handrail to assist the elders while walking and moving up-and-down stairs, and the latter uses two legs and the handrail to assist walking and moving up-and-down stairs (Takahashi et al., 1998). A control bar is attached to the robot waist to assist the aged person by stepping onto the feet of the robot. The robot “Zero Walker-1” (Konuma and Hirose, 2001) focused on ascending and descending stairs. An electric wheelchair named “iBOT” (Independence Technology, 2009), capable of ascending and descending stairs and slopes was released by a Japanese company. In (Sugahara, 2005), a bipedal robot was developed to provide only lower-limbs and a waist, named “WL-16RII”, which can walk independently and allow users to build the upper body based on their requirements. This biped locomotor would be applicable as a walking wheelchair or as a walking support machine that is able to walk up and down stairs carrying or assisting an elder. The developed biped locomotor with Stewart Platform Legs successfully achieved walking up and down on stairs for 250 mm continuously and carrying one 60-kg man on it. Additionally, the authors (Nishiwaki et al., 2002) successfully controlled their robot “H6” to walk up stairs for 250 mm by utilizing toe joints; and the robot “HRP-2” from Harada successfully climbed up 280 mm stairs by grasping the stair rail (Harada et al., 2002). A self-standing type eight-wheeled robot in (Takita et al., 2004) is able to climb up and down stairs and is supported by a mechanism with a planetary gear without an inner gear to eliminate the disadvantages of a wheeled 7