Survey on Fall Detection and Fall Prevention Using Wearable and External Sensors <s> Hirata et al. <s> In this paper, we introduce a passive-type walker using servo brakes referred to as RT Walker. RT Walker realizes several functions such as obstacles/steps avoidance function, path following function, gravity compensation function, variable motion characteristics function, etc., by controlling only servo brakes without using servo motors. These passive-type systems are dependable for using practically in real world environment, because of the passive dynamics with respect to the applied force/moment, simple structure, lightweight, and so on. However, the most serious problem of them is the falling accident of user, because the passive-type systems are lightweight and move easily based on the small force/moment applied by the user unintentionally. In this paper, we pay attention to a method for estimating the human state during the usage of the walker and propose a motion control algorithm for realizing a fall-prevention function based on its human state. We also implement the proposed control methods in RT Walker experimentally and illustrate the validity of them <s> BIB001 </s> Survey on Fall Detection and Fall Prevention Using Wearable and External Sensors <s> Hirata et al. <s> As aging progresses, fall accident of the person using the walker is an acute problem. It is necessary to know the situation of the userpsilas fall to prevent it. In this paper, we propose a method for estimating the userpsilas fall by modeling of the user in real time as a solid body link model, and pay attention to the center of gravity of the model. We also propose a method for controlling a passive intelligent walker to prevent the userpsilas fall according to the support polygon and the walking characteristic of the user. We experimented with passive intelligent walker in which we implement the proposed fall prevention control and show the effectiveness of the proposal method. <s> BIB002
Hirata et al. BIB001 proposed a method that calculates the user's center of gravity position based on the user's skeleton model (human model) in the sagittal plane BIB002 . The system uses passive-type walkers for fall prevention. Two conditions were considered for the creation of the human model. First the user must hold the walker with both hands. Second, the user's limbs (legs and arms) must be measured a priori. Two laser range finders were used, one placed at the same height of user's hip joint, and the other one at the lower part of the walker. The first one is used to create the upper section of the skeleton, and the second one for the lower part. The center of gravity of the human model is used to determine whether the user is within a predefined stability region. If the user is outside the stability region the servo brakes will be triggered making the walker stop. As the walker stops, the user has a better support to accommodate himself/herself and return to the stability region.