Abstract:
The present invention relates to a walking assistance device with detection function, which includes a movable frame, a power transmission device mounted under the frame, a detachable power unit mounted on the frame, at least one signal transmitter and at least one signal receiver for detecting the distances from a first portion and a second portion on the user&#39;s body to a correspond position of the frame respectively. According to the distances detected, a control unit sends signals to the power transmission device to maintain the distance between the user and the frame within a preset range, therefore to provide supporting forces when the user needs.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a walking assistance device, and more particularly, to a walking assistance device with detection members to check the distance between the walking assistance device and the user so as to control the driving of the device. 
       BACKGROUND OF THE INVENTION 
       [0002]    The main purpose of this invention is to provide a walking assistance device with dynamic support by using a sensing device to detect the distances between the device and the user&#39;s individual legs. As we know, a walking assistance device related to this invention was designed by a Japanese scholar Ohigata (as showed in  FIG. 1 ). His design included a frame with multiple rollers, a driving motor to control the motion of frame, and a detection setup to detect the distance between the user and the movable frame. 
         [0003]    The detection setup in Ohigata&#39;s design is to detect the distance between the user&#39;s belly and the walking assistance device. When the distance is less than a pre-set value, the control system of the walking assistance device determines that the user is moving forward and commands the motor to activate the rollers to move forward. When the distance is larger than the pre-set value, the control system sends a signal to let the motor rotate in reversed direction, and thereby the walking assistance device moves backward to keep the distance in the preset range. 
         [0004]    As showed in  FIG. 1 , the detecting and operating ways of Ohigata&#39;s walking assistance device is not safe for the user. In  FIG. 1 , status “a” shows that the user is not moving and status “b” shows that the user starts to move forward, and statuses “c” and “d” show that the user does not move but the frame moves forward, which may make user&#39;s upper body lean forward. As the motor works normally to move the frame forward, the distance between the user&#39;s belly and the detection member is not changed, and the system cannot determine if the user will fall down or not. Statuses “e” and “f” show that the user starts to move but his speed is much slower than that of the rollers. Eventually, the user falls down for that the system cannot detect the situation by simply checking the distance from the user&#39;s belly to the detection member. 
         [0005]    Furthermore, the rear rollers “g” located on two sides of the frame close to the user are designed to turn freely in every direction. In consequence, the frame does not turn about the user when the user wants to turn. Even worse, when the user falls laterally, the two rollers “g” cannot perform a braking function to stop the sliding. 
       SUMMARY OF THE INVENTION 
       [0006]    The main purpose of this invention is to provide dynamic support no matter when the user is walking or standing and to assist the user to move forward or backward without the drawbacks found in the other similar devices. 
         [0007]    In one aspect, this invention provides a walking assistance device equipped with a sensing device to detect the distances between the walker and the user&#39;s individual legs. Based on the measured individual distances, a special control strategy is employed such that the invention can provide dynamic support and assistance. 
         [0008]    In one embodiment of the present invention, the walking assistance device includes a frame with two fixed-direction wheels connected to the rear end of the frame, and a guide wheel mounted to the front end of the frame; a power transmission device, which connects the frame and one of the fixed-direction wheels or the guide wheel; a distance detection device, which is attached to the frame and detects the distance between the two separated positions of the user&#39;s body and the frame, wherein the distance is changeable while using the walking assistance device; and a control device, which is attached to the frame and receives the signals from the distance detection device. The control device includes a calculator to calculate the distances between the two separated positions of the user and the frame and accordingly to send a driving signal to the power transmission device to drive the fixed-direction wheels or the guide wheel. The power transmission device keeps the user within a preset distance range from the frame of the walking assistance device. 
         [0009]    In another aspect, the present invention provides a method for walking assistance, which comprises: 
         [0010]    providing a walking assistance device having a power transmission device; 
         [0011]    providing a distance detection device to detect the signals from the index members on the two legs of the user using the walking assistance device; and 
         [0012]    collecting and transferring the signals to the control device for calculating the distance between the walking assistance device and the two legs of the user and sending a control signal to the power transmission device. 
         [0013]    The primary object of the present invention is to provide a walking assistance device, which can detect the distance between the frame of the walking assistance device and the user and therefore set the appropriate output to the driving device. 
         [0014]    Another object of the present invention is to provide a walking assistance device, wherein the distance between the frame and the legs of the user is detected and checked so as to prevent from falling. 
         [0015]    The present invention will become more obvious from the following description when made reference to the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  shows the using statuses of a similar walking assistance device designed by Ohigata; 
           [0017]      FIG. 2  is a perspective view to show the walking assistance device of the present invention; 
           [0018]      FIG. 3  shows a detailed view of the power transmission device of one embodiment of the walking assistance device according to the present invention; 
           [0019]      FIG. 4  shows the guide wheel of one embodiment of the walking assistance device according to the present invention; 
           [0020]      FIG. 5  shows the using status of one embodiment of the walking assistance device according to the present invention; 
           [0021]      FIG. 6  shows the using statuses, viewed from top, of one embodiment of the walking assistance device according to the present invention, and 
           [0022]      FIG. 7  shows the using status of another embodiment of the walking assistance device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Referring to  FIGS. 2 to 4 , the walking assistance device of the present invention comprises a movable frame  20  to which a power transmission device  40  and a detachable distance detection device  60  for detecting the distance between the frame  20  and the user&#39;s legs. A control device  80  for controlling the power transmission device  40  is attached to the frame  20 . 
         [0024]    The frame  20  includes a holding part with proper shape and structure for user&#39;s holding, and a moving unit which allows the frame  20  to be stably located on the ground. The moving unit comprises two fixed-direction wheels  22 , which are mounted to the rear end of the frame  20  and rotatable toward a pre-set direction, such as back and forth. The two fixed-direction wheels  22  are located on two sides of the frame  20  and separated by a distance defined as zone  24 , where the user can stand or walk within. Two turning wheels  26  are mounted to the front end of the frame  20  and are rotatable in all direction. 
         [0025]    The power transmission device  40  mounted to the front end of the frame  20  includes a motor  42 , a guide wheel  46 , and a gear reduction set  44  which connects the output end of the motor  42  and the guide wheel  46 . The guide wheel  46  includes two casings  460  mounted onto a shaft  462  which is parallel to a first axis on the ground. Eight separation members  464  are mounted on the counter ends of the two casings  460  at even intervals. Each driving roller  466  is mounted in the space between two of the separation members  464 . The driving rollers  466  protrude from the outer surface of the casings  460  so as to be able to contact with the ground. 
         [0026]    The distance detection device  60  includes two physical or virtual index members  62  which may be fixed on the two separated position of user&#39;s body and be removed from the user&#39;s body if necessary. The index members  62  emit or reflects individual signals, such as ultra-sonic signals, laser beams, infrared, or visible light. When the user moves forward or backward, the index members  62  move with the two separated positions of the user&#39;s body. Thereafter, the respective distances of the two separated positions to the frame  20  are changed. In this embodiment, the two separated positions are located on the ankles of the user&#39;s legs, and the index members  62  emit ultrasonic signals. 
         [0027]    The distance detection device  60  further includes detection member  64 , which is fixed on the frame  20  and located in front of the zone  24 , respectively. In this embodiment, two ultrasonic detection members  64  are used and located in front of the zone  24  for receiving signals from the two index members  62 , and then sending signals to the control device  80 . 
         [0028]    The control device  80  located above the power transmission device  40  receives the signals from the distance detection device  60  and calculates the two respective distances from each ankle of the user to a reference vertical plane on the frame  20 , as well as the mean value of the respective distances. The mean value of the respective distances is compared with a pre-set value so as to accordingly send a control signal to the motor  42  of the power transmission device  40  through a wired or wireless communication method. 
         [0029]      FIG. 5  shows that the interaction between the index members  62  and detection members  64 .  FIG. 6 , from left to right, shows the continuous steps of the user who moves forward by stepping out the right leg S 1 , and then the left leg S 2 , and then stops. 
         [0030]    When the mean value of the respective distances between the frame  20  and each ankle of the user is less than an acceptable value compared to the pre-set value, the control device  80  determines that the current motion status of the frame  20 , either stationary for moving, can keep the user within the zone  24 , and no different control signal is sent to the power transmission device  40 . For instance, the pre-set value is 34 cm and the acceptable value is 2 cm. When the respective distances from the left ankle and right ankle of the user to the reference vertical plane on the frame  20  are 32 cm and 35 cm, the mean value of the two distances is 33.5 cm and has 0.5 cm difference from the pre-set value. For that the average distance is not more than the acceptable value (2 cm), no different control signal is required. 
         [0031]    When the mean value of distances from the left ankle and right ankle of the user to the reference vertical plane on the frame  20  is less than the pre-set value, and the difference is more than the acceptable value, the control device  80  determines that the two legs of the user are too close to the frame  20 , and then sends a different control signal, e.g. to increase speed, to the motor  42  for driving the guide wheels  46  to move the frame  20  away from the user. 
         [0032]    On the contrary, if the average of distances from the left ankle and right ankle of the user to the reference vertical plane on the frame  20  is more than the pre-set value, and the difference is more than the acceptable value, the control device  80  determines that the user&#39;s two legs are far behind the zone  24 . Therefore, a different control signal, e.g. to reduce speed, is sent to the motor  42  for driving the guide wheels  46  to move the frame  20  close to the user so as to provide a support to the user and reduce the risk of falling. 
         [0033]    As described above, the two index members  62  emit signals to the distance detection device  60  for the control device  80  to determine the relative distance between the user and frame  20 . In the other embodiment, as shown in  FIG. 7 , when the two index members  62  are set to reflect signals, a signal emitting member is mounted to the front end of the frame  20  and installed in the control device  80 . The signals emitted from the signal emitting member are reflected from the two index members  62  and received by the distance detection device  60 . The control device  80  detects, calculates, and determines the signals, and then generates control signals to operate the walking assistance device  10 . 
         [0034]    In the embodiments of present invention, the zone  24  is defined as the area between the fixed-direction wheels  22 . For that the fixed-direction wheels  22  can only move back and forth, it is possible to prevent the user from falling aside. Actually, the zone  24  can also be defined as the area that is located slightly behind the fixed-direction wheels  22 . 
         [0035]    It is noted that the motor  42  does not necessarily connected to the guide wheel  46 , but can also be connected to the fixed-direction wheels  22  or the turning wheels  26 . 
         [0036]    While we have shown and described the embodiment according to the present invention, it should be clear to those who skilled that further embodiments may be made without departing from the scope of the present invention.