Patent Publication Number: US-2009234576-A1

Title: Navigation device and method

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to navigation, and particularly relates to a navigation device and method for use by the visually impaired. 
     2. Description of Related Art 
     Navigation devices are widely used to help the visually impaired. A popular navigation device is an electronic talking stick which outputs audio instructions for walking such as ascending and descending stairways. The electronic talking stick also warns a visually impaired individual of impending danger, such as depressions and obstacles in a pathway being traversed, and if need be the electronic walking stick can even call for help. However, most electronic talking stick are limited to obtaining the distance to the potential dangerous objects, and cannot measure the heights or depths or other parameters of the depressions or obstacles in the pathway. 
     Therefore, a navigation device and a navigation method are needed in the industry to address the aforementioned deficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram showing a navigation device in accordance with an exemplary embodiment. 
         FIG. 2  is a schematic diagram showing a mathematic model for illustrating a working principle of the navigation device in  FIG. 1 . 
         FIG. 3  is a schematic diagram showing a positive situation of the mathematic model. 
         FIG. 4  is a schematic diagram showing a negative situation of the mathematic model. 
         FIG. 5  is a schematic diagram showing an irregular object measured by the navigation device. 
         FIG. 6  is a schematic diagram showing an irregular recess measured by the navigation device. 
         FIG. 7  is a schematic diagram showing an incline measured by the navigation device. 
         FIG. 8  is a schematic diagram showing a decline measured by the navigation device. 
         FIG. 9  is a schematic diagram showing a wall measured by the navigation device. 
         FIG. 10  is a schematic block diagram showing a navigation device in accordance with another exemplary embodiment. 
         FIG. 11  is a schematic block diagram showing a navigation device in accordance with another exemplary embodiment. 
         FIG. 12  is a schematic block diagram showing a digital map used by the navigation device in  FIG. 10 . 
         FIG. 13  is a flowchart showing a navigation method in accordance with an exemplary embodiment. 
         FIG. 14  is a flowchart showing a navigation method in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a navigation device  100  in accordance with an exemplary embodiment is capable of aiding the visually impaired with audio alerts. The navigation device  100  includes a memory  11 , a transceiver  12 , a timer  13 , an angle detector  14 , a processor  15 , and a speaker  16 . 
     The memory  11  stores an alerting program and a predetermined safe value. The transceiver  12  projects a detecting signal repeatedly at predetermined time intervals, receives the detecting signal reflected from obstacles. The timer  13  calculates a time interval between projecting the detecting signal and receiving the detecting signal reflected from the obstacles. The angle detector  14  detects a projecting angle of the detecting signal projected from the transceiver  12  with respect to the vertical direction. The processor  15  calculates a horizontal distance to the obstacle and a size of the obstacle (a height of an object or a depth of a recess), and calls the alert program from the memory  11  to generate an alert signal according to the horizontal distance and the size. The speaker  16  reproduces an audio alert according to the alert signal. 
     The angle detector  14  may be a magnetic-sensing resistor. When the angle detector  14  is rotated, the magnetic-sensing resistor can detect an angular displacement of the magnetic field, convert the angular displacement to an electrical signal, and calculate the projecting angle according to the electrical signal. The angle detector  14  may include an angle counter (not shown). When the angle detector  14  is rotated by a predetermined angle perpendicular to gravity, the angle counter will increment by a constant. When the angle detector  14  is turned to another direction opposite to the predetermined angle, the angle counter will decrement by the constant. In this way, the angle detector  14  can output the projecting angle via the angle counter. The angle detector  14  may also be a liquid level measuring apparatus which measures a rotated angle according to a liquid level variance of the liquid level measuring apparatus. 
     Referring to  FIG. 2 , a schematic diagram illustrates how the processor  15  calculates the horizontal distance to an obstacle  900  and the size of the obstacle  900 . The obstacle  900  shown as a circle on the ground provides a first example of a mathematic model for calculating the horizontal distance and the size. In the first example: a velocity “V” of the detecting signal is known, a time interval “T” between projecting the detecting signal and receiving the detecting signal reflected from obstacle  900  is measured, a projecting angle “α” of the detecting signal with respect to the vertical direction, and a height “AB” of the navigation device  100  with respect to the ground is measured. 
     According to diagram, the detecting signal projected and the detecting signal reflected are transmitted between a point A (the position of the navigation device  100 ) and a point C. The distance between the point A and the point C can be calculated applying a first equation “AC=V*T/2”. Therefore, the horizontal distance, from a point D to the point C, can be calculated applying a second equation “DC=AC*sin ∠α=(V*T*sin ∠α)/2”. The size of the obstacle  900 , the same as a height from the point D to the point B, can be calculated applying a third equation “DB=AB−AD=AB−AC*cos ∠α=AB−(V*T*cos ∠α)/2”. 
     The processor  15  compares an absolute value of the size DB with the predetermined safe value stored in the memory  11 . If the absolute value does not exceed the predetermined safe value, the navigation device  100  makes no response and continues to project the detecting signal. If the absolute value exceeds the predetermined safe value, the processor  15  determines whether the size DB is positive or negative. If the size DB is positive, that means the obstacle is an object on the ground (see  FIG. 3 ), and the processor  15  will generate a positive signal. If the size DB is negative, that means the obstacle is a recess below the ground (see  FIG. 4 ), and the processor  15  will generate a negative signal. 
     The processor  15  calls the alerting program to generate an alert signal. The alert signal includes data indicating the horizontal distance DC, the size DB, and the positive/negative signal. The speaker  16  reproduces an audio alert according to the alert signal. For example, the speaker  16  may reproduce “there is a DB meter high object DC meters from here”. 
     Referring to  FIG. 5 , the navigation device  100  is used to get information of an irregular object  910  to depict its profile. The navigation device  100  is used to measure each point of the irregular object  910 . In operation, the navigation device  100  scans the irregular object  910  by projecting a detecting signal to each point of the irregular object  910  and receiving the detecting signal. For each point of the irregular object  910 , the navigation device  100  uses the same method as detailed above in calculating information of the point C of the obstacle  900  in  FIG. 2 . Similarly, also referring to  FIG. 6 , the navigation device  100  is also used to get information of an irregular recess  920  to depict its profile. In operation, the navigation device  100  scans the irregular recess  920  by projecting a detecting signal to each point of the irregular recess  920  and receiving the detecting signal reflected therefrom. For each point of the irregular recess  920 , the navigation device  100  uses the same method as detailed above in calculating information of the point C of the obstacle  900  in  FIG. 2 . 
     Furthermore, when the navigation device  100  is used for measuring some regular obstacles, the navigation device  100  measures some key points rather than each point of the obstacles to get basic information of the obstacles. Some actual instances are set forth in  FIGS. 7-9 .  FIG. 7  shows an incline  930  in front of the navigation device  100 . The navigation device  100  measures three points C, E, G of the incline  930 . For the three points, there are corresponding projecting angles α, β, γ, and time intervals T 1 , T 2 , T 3 . Therefore, horizontal distances of the points C, E, G are “BC=(V*T 1 *sin ∠α)/2”, “DE=(V*T 2 *sin ∠β)/2”, “FG=(V*T 3 *sin ∠γ)/2”, and heights of the points C, E, G are “0”, “DB=AB−(V*T 2 *cos ∠β)/2”, “FB=AB−(V*T 3 *cos ∠γ)/2”. If FB&gt;DB&gt;0 and FG&gt;DE&gt;BC, the processor  15  generates an alert signal to inform the visually impaired of the incline  930 . The speaker  16  may reproduce “there is an incline BC meters from here”. 
       FIG. 8  shows a decline  940 . The navigation device  100  measures three points C, E, G of the decline  940 . For the three points, there are corresponding projecting angles α, β, γ, and time intervals T 1 , T 2 , T 3 . Therefore, horizontal distances of the points C, E, G are “BC=(V*T 1 *sin ∠α)/2”, “DE=(V*T 2 *sin ∠β)/2”, “FG=(V*T 3 *sin ∠γ)/2”, and depths of the points C, E, G are “0”, “DB=AB−(V*T 2 *cos ∠β)/2”, “BF=AB−(V*T 3 *cos ∠γ)/2”. If FB&lt;DB&lt;0 and FG&gt;DE&gt;BC, the processor  15  generates an alert signal to inform the visually impaired of the decline  940 . The speaker  16  may reproduce “there is a decline BC meters from here”. 
       FIG. 9  shows a wall  950 . The navigation device  100  measures three points C, E, G of the wall  950 . For the three points, there are corresponding projecting angles α,  3 ,  7 , and time intervals T 1 , T 2 , T 3 . Therefore, horizontal distances of the points C, E, G are “BC=(V*T 1 *sin ∠α)/2”, “DE=(V*T 2 *sin ∠β)/2”, “FG=(V*T 3 *sin ∠γ)/2”, and heights of the points C, E, G are “0”, “DB=AB−(V*T 2 *cos ∠β)/2”, “BF=AB−(V*T 3 *cos ∠γ)/2”. If FB&gt;DB&gt;0 and FG=DE=BC, the processor  15  generates an alert signal to inform the visually impaired of the wall  950 . The speaker  16  may reproduce “there is a wall BC meters from here”. 
     Referring to  FIG. 10 , a navigation device  200  in accordance with another exemplary embodiment is capable of aiding the visually impaired with not only audio alerting but also routine navigation. The navigation device  200  includes a memory  21 , a transceiver  22 , a timer  23 , an angle detector  24 , a processor  25 , a speaker  26 , a communication module  27 , and an inputting module  28 . The timer  23  and the angle detector  24  execute the same function as the timer  13  and the angle detector  14  respectively. In comparison with the navigation device  100 , the memory  21 , the communication module  27 , and the inputting module  28  are distinctive and depicted as follows. 
     The memory  21  stores not only an alerting program but also a digital map. The inputting module  28  can be used to input a destination. For the visually impaired, the inputting module  28  may be designed as a sound recorder which inputs the destination by recording sound of the visually impaired. The communication module  27  receives a location signal, which indicates a current location of the visually impaired, from satellites. Moreover, the processor  25  searches the destination in the digital map, and then selects an optimum course from the location of the visually impaired to the destination. The processor  25  also calls the alerting program to generate an alert signal according to the optimum course. The speaker  26  reproduces an audio alert according to the alert signal. Moreover, referring to  FIG. 11 , a navigation device  300  uses a Bluetooth® earphone  31  to replace the speaker  26 , and uses a Bluetooth® module  32  to replace the inputting module  28 . Therefore, the navigation device  300  can facilitate the visually impaired with a wireless service. 
     The processor  25  of the navigations  200  also can determine whether the visually impaired strayed from the optimum course. Referring to  FIG. 12 , a digital map  777  is shown with an optimum course from A-B-C, and a current position is D which is off-course from the line A-B. In this case, the processor  25  calculates an angle between the line A-B and the line A-D. If the angle is beyond a predetermined angle stored in the memory  21 , the processor  25  calls the alerting program to generate an alert signal to notice the visually impaired to walk along the optimum course. The speaker  26  reproduces an audio alert according to the alert signal. 
     Referring to  FIG. 13 , a navigation method in accordance with an exemplary embodiment is capable of aiding the visually impaired with an audio alert. Hereafter, the navigation device  100  is taken as a carrier performing the navigation method. 
     In step S 151 , the transceiver  12  projects a first detecting signal vertically to the ground, and receives the first detecting signal reflected from the ground. 
     In step S 152 , the transceiver  12  projects a second detecting signal forward at predetermined intervals, and receives the second detecting signal reflected from an obstacle. 
     In step S 153 , the timer  13  calculates a first time interval between projecting and receiving in step S 151 , and calculates a second time interval between projecting and receiving in step S 152 . 
     In step S 154 , the angle detector  14  detects a projecting angle of the second detecting signal projected from the transceiver  12  with respect to the vertical direction. 
     In step S 155 , the processor  15  calculates a horizontal distance to the obstacle and a size of the obstacle according to the first time interval, the second time interval, a first velocity of the first detecting signal, a second velocity of the second detecting signal, and the projecting angle. In the embodiment, the first detecting signal and the second detecting signal have the same velocity. In other embodiments, they may have different velocities. 
     In step S 156 , the processor  15  compares an absolute value of the size of the obstacle with a predetermined safe value. If the absolute value does not exceed the predetermined safe value, step S 152  is next. If the absolute value exceeds the predetermined safe value, step S 157  is next. 
     In step S 157 , the processor  15  determines whether the size is positive or negative. If the size is positive, step S 158  is next. If the size is negative, step S 159  is next. 
     In step S 158 , the processor  15  generates a positive signal. 
     In step S 159 , the processor  15  generates a negative signal. 
     In step S 160 , the processor  15  calls the alerting program to generate an alert signal according to the horizontal distance, the size, and the positive/negative signal. 
     In step S 161 , the speaker  16  reproduces an audio alert according to the alert signal. 
     Referring to  FIG. 14 , a navigation method in accordance with another exemplary embodiment is capable of aiding the visually impaired with routine navigation. Detailed steps of the navigation method used by a navigation device (the navigation device  200  for example) are set forth as follows. 
     In step S 171 , the inputting module  28  inputs a destination. 
     In step S 172 , the communication module  27  receives a location signal indicating a location of the visually impaired from satellites. 
     In step S 173 , the processor  25  searches the destination in a digital map. 
     In step S 174 , the processor  25  selects an optimum course from the location to the destination. 
     In step S 175 , the processor  25  calls the alerting program to generate an alert signal according to the optimum course. 
     In step S 176 , the speaker  26  reproduces an audio alert according to the alert signal. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.