Walking Shoe

CROSS REFERENCE TO RELATED APPLICATIONS

0001The present application is a continuation of International application No. PCT/JP2011/055579, filed Mar. 10, 2011, which claims priority to Japanese Patent Application No. 2010-058756, filed Mar. 16, 2010, the entire contents of each of which are incorporated herein by reference.

FIELD OF THE INVENTION

0002The present invention relates to a walking shoe, and particularly to a shoe having a fall prevention function.

BACKGROUND OF THE INVENTION

0003A situation may occur where not only elderly people but also a generation that is generally unrecognized as the elderly people, for example, people in their late 40 s to 50 s unexpectedly stumble over a step, which they would not have stumbled in their early days. It is considered that this occurs because raising of a foot or an angle of a toe is insufficient, as compared with a walking state under a condition where the people do not stumble. Normally, the people are unaware of this insufficiency, and the foregoing often occurs unconsciously due to age-related weakening eyesight, deterioration of cognitive ability, muscular weakness, and the like. Moreover, an endurance capacity is also deteriorated, and thus, when the people become tired with prolonged walking, a similar phenomenon may be caused.

0004In Patent Document 1, there is disclosed a walking observing apparatus that detects whether or not abnormal walking occurs in an elderly person wearing the observing apparatus at his or her waist to collect data during walking of the wearer. By giving appropriate prescription to the elderly person in accordance with the collected data, measures to prevent falls or the like are taken.

0005In Patent Document 2, there is disclosed a fall prevention training assist apparatus including an inclination sensor mounted on a side surface of a supporter to be worn on a foot, a sound generating unit that generates sound by a signal of the inclination sensor, and a pressure sensor mounted on a lower side of a heel of the supporter. An inclination angle of a toe of the foot is sensed by the inclination sensor, and when determined that the inclination angle is insufficient as compared with that of normal walking, the wearer is notified by the sound generated by the sound generating unit to assist, for example, training to normalize walking of an elderly person.

0006However, the observing apparatus described in Patent Document 1 is intended to observe the walking of the elderly person to collect the data, and is not intended to prevent falls during actual walking.

0007Patent Document 2 describes that a person stumbles over a doorsill or the like and falls because the inclination angle of the foot is small. However, for example, when the person ascends the step or the like, not only the inclination angle of the foot but also a lifting amount of the foot or a lifting velocity give influence. Therefore, when only the inclination angle of the foot is detected, the person cannot necessarily ascend the step without stumbling. In Patent Document 2, the walker, while listening to the sound generated when the inclination angle of the foot taking a step is at a predetermined level or higher, learns how to walk so as to emit the sound. However, when the person actually almost falls, the apparatus does not sense the fall to urge the person to perform movement for fall prevention.

0008Patent Document 1: Japanese Unexamined Patent Publication No. H10-165395

0009Patent Document 2: Japanese Unexamined Patent Publication No. 2006-158431

SUMMARY OF THE INVENTION

0010An object of the present invention is to provide a walking shoe that senses a fall when a walker stumbles or almost falls, and urges the walker to perform movement for fall prevention.

0011In order to achieve the above-described object, a first embodiment of the present invention provides a walking shoe including: a shoe body that receives a foot, a stimulator that is mounted on the shoe body and stimulates a bottom of the foot, an acceleration sensor that is mounted on the shoe body, and capable of detecting an acceleration in a direction parallel to ground acting on the shoe body and an acceleration in a direction perpendicular to the ground, and a microprocessor that is mounted on the shoe body, detects a lifting velocity and/or a lifting amount of the foot, based on a detection signal of the acceleration sensor, and actuates the stimulator when determined that the lifting velocity and/or the lifting amount is lower than a reference value.

0012A second embodiment of the present invention provides a walking shoe including: a shoe body that receives a foot, a stimulator that is mounted on the shoe body and stimulates a bottom of the foot, an acceleration sensor that is mounted on the shoe body, and capable of detecting an acceleration in a direction parallel to ground acting on the shoe body and an acceleration in a direction perpendicular to the ground, a ranging sensor that is mounted on a front end portion of the shoe body, and detects a distance between the shoe body and a front obstacle, and a microprocessor that is mounted on the shoe body, determines whether or not there is a possibility that the shoe body collides with the front obstacle from a detection signal of the acceleration sensor and a detection signal of the ranging sensor, and actuates the stimulator when determined that the shoe body collides.

0013During walking, as long as a foot taking a step has a sufficient height, a user does not stumble. This height is roughly decided by the lifting amount of the foot (or thigh) and an angle of a toe. There are differences among individuals in the manner of walking, and a raising amount of the thigh and a raising amount of the toe vary among people. In the first embodiment, when the walking starts, the lifting velocity or the lifting amount of the foot is detected based on the detection signal of the acceleration sensor. The lifting velocity can be obtained directly from the signal of the acceleration sensor, and the lifting amount can be obtained by integrating the lifting velocity. When determined that the detected lifting velocity or lifting amount is lower than the reference value, the stimulator is actuated. As described above, with aging and fatigue of the person, the lifting velocity or the lifting amount of the foot incidentally becomes insufficient, resulting in the stumbling. At this time, when any stimulation is received from the bottom of the foot, a human reflexively performs movement of lifting the foot. The present invention utilizes this movement to prevent the stumbling from occurring. While a fixed value set in advance may be used as the reference value, for example, the reference value may also be decided from accumulated data of the past lifting velocity or the lifting amount.

0014In the second embodiment, whether or not there is a possibility that the shoe body collides with the front obstacle is determined from the detection signal of the acceleration sensor and the detection signal of the ranging sensor, and when determined that the shoe collides with the obstacle, the stimulator is actuated. For example, when ascending a step or stairs, a person decides the lifting amount of the foot while checking the step or the stairs from the past experience, based on information obtained from eyesight, and lifts the foot unconsciously. However, when determined that the lifting amount is insufficient and that a forefront of the shoe will collide with the obstacle, the bottom of the foot is slightly stimulated by the stimulator embedded in the shoe, which can urge the user of the shoe to perform movement for fall prevention.

0015In the walking shoe of the second embodiment, as a method of the collision determination, for example, a trajectory of the shoe may be calculated based on the detection signal of the acceleration sensor, and whether or not there is a possibility that the shoe body collides with the front obstacle may be determined from the trajectory and the distance between the shoe body and the front obstacle, which has been obtained from the detection signal of the ranging sensor. In this case, accuracy of the collision determination is improved, which can prevent the stimulator from being needlessly actuated.

0016In the walking shoe of the second embodiment, the microprocessor may determine whether a walking mode is a step ascent mode or a normal walking mode based on the detection signal of the acceleration sensor, and when determined that the walking mode is the step ascent mode, whether or not there is a possibility that the shoe body collides with the front obstacle may be determined. During the normal walking, the lifting velocity or the lifting amount of the shoe is more likely to cause stumbling than the collision of the shoe with an obstacle, whereas when the user ascends a step, the collision with the front obstacle (step or the like) mainly causes stumbling.

0017A pressure-sensitive sensor to sense a pressure applied to a tread may be mounted on a bottom portion of the shoe body. Since the pressure-sensitive sensor can reliably detect whether or not the foot has landed, the walking state (whether or not the user is walking or the like) can be determined by a sensing signal of the pressure-sensitive sensor. When a piezoelectric element is used as the pressure-sensitive sensor, the pressure-sensitive sensor need not be constantly powered, and applying a pressure from outside allows the signal to be outputted, which enables the pressure-sensitive sensor to be used as a trigger. For example, when a state where the acceleration sensor does not generate the signal lasts for a predetermined time, the microprocessor may be put into a standby state, and by sensing the signal of the pressure-sensing sensor, the microprocessor may be returned to an activated state. That is, when the shoe is not used, the circuit is put into the standby state where power consumption is suppressed, and when the shoe is used, a voltage generated by the pressure-sensitive sensor is sensed to return the circuit from the standby state to the activated state, by which wasteful power consumption can be eliminated.

0018The microprocessor may have a memory that automatically samples a walking situation for a predetermined period to store a trajectory generated most frequently as a shoe trajectory of a user. In this case, since this shoe itself learns a habit and a situation of the user as a use period elapses, stimulation control in accordance with the user can be performed.

0019As described above, according to the present invention, when the user almost falls, it is sensed and the bottom of the foot is stimulated, by which the user of the shoe reflectively lifts the foot, thereby preventing stumbling or falls.

BRIEF DESCRIPTION OF THE DRAWINGS

0020<figref idref="DRAWINGS">FIG. 1</figref> is a diagram showing a cross section of one example of a shoe of the present invention.

0021<figref idref="DRAWINGS">FIG. 2</figref> is a diagram schematically showing movement of a skeletal structure when a person walks.

0022<figref idref="DRAWINGS">FIG. 3</figref> is a diagram schematically showing movement of a leg during normal walking.

0023<figref idref="DRAWINGS">FIG. 4</figref> is a diagram schematically showing movement of the leg when a person ascends a step.

0024<figref idref="DRAWINGS">FIG. 5</figref> is a flowchart showing one example of processing algorithm of a microprocessor.

0025<figref idref="DRAWINGS">FIG. 6</figref> is a diagram showing movement of the shoe when a person ascends the step.

0026<figref idref="DRAWINGS">FIG. 7</figref> is a flowchart showing another example of the processing algorithm of the microprocessor.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

0027<figref idref="DRAWINGS">FIG. 1</figref> shows a shoe <b>1</b> and a foot <b>2</b> of a user. A ranging sensor <b>10</b> for sensing an obstacle is mounted on a front end portion of the shoe <b>1</b>, and a stimulator <b>11</b> that stimulates a bottom of the foot is embedded in a sole portion. A pressure-sensitive sensor <b>12</b> that senses a pressure applied to a tread is mounted in a tread portion <b>1</b><i>a </i>of the shoe <b>1</b>, for example, in a heel portion and at a position corresponding to a heel. Furthermore, a waist portion <b>1</b><i>b </i>(on a rear surface side) of the shoe <b>1</b> is provided with an acceleration sensor <b>13</b>, a microprocessor <b>14</b>, and a battery <b>15</b>. Mounting positions of the acceleration sensor <b>13</b>, the microprocessor <b>14</b>, and the battery <b>15</b> are not limited to those in <figref idref="DRAWINGS">FIG. 1</figref>, and may be embedded in other sites of the shoe <b>1</b> such as the tread portion <b>1</b><i>a</i>, a lining portion, and the like. These elements are mutually connected through wiring <b>16</b>.

0028The ranging sensor <b>10</b> is mounted on the front end portion of the shoe <b>1</b> to detect a distance to a front step or a front obstacle. As the ranging sensor <b>10</b>, a publicly known sensor such as an ultrasonic sensor and an infrared sensor can be used.

0029The stimulator <b>11</b> is a device that drives an actuation pin <b>11</b><i>a </i>by an actuator in an electromagnetic method, a piezoelectric method, or the like to stimulate the bottom of the foot. Immediately after the bottom of the foot is stimulated, the actuation pin <b>11</b><i>a </i>is released from an actuated state so that the bottom of the foot is not excessively stimulated. Accordingly, even if the user enters a state of stepping on the stimulator <b>11</b>, the pin <b>11</b><i>a </i>does not stick in the bottom of the foot. <figref idref="DRAWINGS">FIG. 1</figref> shows an example of the stimulator <b>11</b> in which the actuation pin <b>11</b><i>a </i>stimulates the bottom of the foot, however, the present invention is not limited thereto, and a device that gives slight vibration to the bottom of the foot, such as a piezoelectric element and a vibration motor, may be employed.

0030The pressure-sensitive sensor <b>12</b> is a sensor that senses the pressure applied to the tread portion <b>1</b><i>a</i>, so as to detect whether or not the shoe <b>1</b> has departed from ground. In <figref idref="DRAWINGS">FIG. 1</figref>, the pressure-sensitive sensor <b>12</b> is mounted on the heel portion, but the present invention is not limited thereto. The pressure-sensitive sensor <b>12</b> is made of, for example, a piezoelectric element or the like, and performs sensing by changing the pressure by walking into electricity. The electricity is continuously generated during walking, and thus, when the electricity is not used for the sensing, this electric power is regenerated in the battery <b>15</b>, so that drain of the battery <b>15</b> can also be prevented. When the power consumption itself is very small, the electric power generated by the pressure-sensitive sensor <b>12</b> can be charged. As a material of the piezoelectric element, lead zirconate titanate (PZT), polyvinylidene fluoride (PVDF), polylactic acid (PLLA), or the like can be used. Besides the piezoelectric element, an electret or electrostatic method can also be used.

0031The acceleration sensor <b>13</b> is a biaxial acceleration sensor that senses an acceleration in a direction parallel to the ground (front-back direction), and an acceleration in a direction perpendicular to the ground (up-down direction). In addition to the foregoing, a triaxial acceleration sensor capable of sensing an acceleration in a right-left direction may also be used. A mounting position of the acceleration sensor <b>13</b> is not limited to the heel portion as shown in <figref idref="DRAWINGS">FIG. 1</figref>, but any position may be employed.

0032The microprocessor <b>14</b> receives a signal from the acceleration sensor <b>13</b> at predetermined time intervals and subjects this signal to arithmetic operation processing, by which a trajectory of the shoe <b>1</b> (a lifting velocity, a lifting amount, a forward velocity, a forward amount, an inclination angle, and the like) can be obtained. Also, signals are received from the ranging sensor <b>10</b> and a pressure-sensitive sensor <b>12</b>, so that the distance to a front obstacle can be obtained based on the signal from the ranging sensor <b>10</b>, and whether or not the shoe <b>1</b> has departed from the ground can be determined based on the signal from the pressure-sensitive sensor <b>12</b>. The microprocessor <b>14</b> controls the stimulator <b>11</b> based on the signals from the sensors <b>10</b>, <b>12</b>, <b>13</b>. While the microprocessor <b>14</b> includes therein an internal memory, the microprocessor <b>14</b> may be provided with an external memory.

0033As the battery <b>15</b>, a small battery such as a button battery is desirable, and the battery <b>15</b> is exchangeable as needed. A solar battery can also be used as the battery <b>15</b>, and in the case where the pressure-sensitive sensor <b>12</b> has an electric generation function, the battery may have a function of storing the generated electric power. Furthermore, a power generating device that generates electric power based on the movement of the shoe may be provided separately.

0034<figref idref="DRAWINGS">FIG. 2</figref> schematically shows a skeletal structure when a person is walking. Reference numeral <b>20</b> denotes a hip joint, <b>21</b>, <b>22</b> each denote a thigh bone, <b>24</b>, <b>25</b> each denote a knee joint, and <b>26</b>, <b>27</b> each denote a tibial bone, which are modelized. A trajectory <b>23</b> indicates a trajectory drawn by the knee joints <b>24</b>, <b>25</b>, centering on the hip joint <b>20</b>. Moreover, a trajectory <b>28</b> indicates a trajectory drawn by a forefront of the tibial bone <b>26</b>, centering on the knee joint <b>24</b>. Moreover, a trajectory <b>29</b> indicates a trajectory drawn by a forefront of the tibial bone <b>27</b>, centering on the knee joint <b>25</b>.

0035During walking, the thigh bones move like pendulums at angles of 20° to 30° centering on the hip joints, and the tibial bones move like pendulums at angles of 40° to 50° centering on the knee joints. The angles are not limited to the foregoing, but vary among individuals, and in each of individual persons, these angles during walking are almost constant. A pelvis moves almost horizontally with respect to a walking direction, the tibial bones move like the pendulums, centering on the knee joints, which are forefronts of the thigh bones moving like the pendulums. Therefore, if an angle of a toe is not considered, the shoe itself moves like a duplex pendulum controlled by muscles. This movement is shown in <figref idref="DRAWINGS">FIG. 2</figref>.

0036Attention is paid to the movement of one leg during ordinary walking, which is shown in <figref idref="DRAWINGS">FIG. 3</figref>. <figref idref="DRAWINGS">FIG. 3</figref> focuses on a left leg in <figref idref="DRAWINGS">FIG. 2</figref>, and schematically shows an image as if the left leg during walking is photographed by stroboscope.

0037Arrow <b>30</b> indicates the walking direction. With the movement by walking, a state of the leg changes in order of a state <b>31</b>, a state <b>32</b>, a state <b>33</b>, a state <b>34</b>, and a state <b>35</b>. The state <b>31</b> indicates a state immediately before the toe kicks up from ground G. Although the hip joint <b>20</b> is illustrated to move in parallel to the ground G in the states <b>31</b> to <b>35</b>, actually, slight vertical movement is caused by movement of the other leg.

0038When shifting from the state <b>31</b> to the state <b>32</b>, the bottom of the foot departs from the ground G in order to carry the foot forward. In the knee joint, the angle is increased in order to lift the toe from the ground G. In the state <b>33</b>, the thigh bone <b>21</b> is swung forward with respect to a body, and at about this point, the knee joint <b>24</b> shifts in a direction where it is completely extended (the angle of 0°), and goes through the state <b>34</b> to reach the state <b>35</b>.

0039This movement when the person walks is almost constantly repeated. The microprocessor <b>14</b> monitors the trajectory of the shoe <b>1</b> at this time based on the detection signal of the acceleration sensor <b>13</b>. Since the movement of the shoe <b>1</b> has an acceleration in any direction with respect to the ground G at any time point, the movement can be monitored by the acceleration sensor <b>13</b>.

0040The microprocessor <b>14</b> senses the signal of the acceleration sensor <b>13</b> every predetermined period and subjects this sensing signal to the arithmetic operation processing, by which the trajectory of the shoe <b>1</b> during normal walking can be obtained. The trajectory of the shoe <b>1</b> during normal walking is held in the memory inside the microprocessor <b>14</b> after a sampling period. A mechanism may be employed in which the sampling period can be uniquely set by the user of the shoes, or after the user buys the shoes, walking situations for several hours or for several days after the microprocessor <b>14</b> is first activated are automatically sampled. The microprocessor <b>14</b> stores the trajectory occurring most frequently in the memory as a trajectory of the shoe of the user. As to the determination of the trajectory, a plurality of trajectories are recognized as the same trajectory, using a threshold.

0041When the shoe <b>1</b> is not worn, the microprocessor <b>14</b> keeps current consumption to a minimum to suppress consumption of the battery <b>15</b>. If the acceleration sensor <b>13</b> does not react for a predetermined period, the microprocessor <b>14</b> enters a standby state, and when receiving the signal from the pressure-sensitive sensor <b>12</b>, the microprocessor <b>14</b> enters an activated state.

0042If the microprocessor <b>14</b> is in the activated state, and the user has started walking, the trajectory of the shoe <b>1</b> is determined based on the signal of the acceleration sensor <b>13</b>. While this trajectory is determined to be within a range of the normal walking, the processing here is only repeated.

0043Next, a motion of the leg when the user tries to ascend a step (or an obstacle) S will be described with reference to <figref idref="DRAWINGS">FIG. 4</figref>. When the user ascends stairs, or when the user steps over something, the movement of the leg changes as compared with the movement during the normal walking. Arrow <b>40</b> indicates the walking direction, and the state of the leg sequentially changes from a state <b>41</b> to a state <b>45</b>. The forward velocity is reduced from the state <b>41</b> to the state <b>42</b>, and from the state <b>42</b> to the state <b>45</b>, the thigh bone <b>21</b> is lifted at a larger angle as compared with the case in <figref idref="DRAWINGS">FIG. 3</figref>. The tibial bone <b>26</b> is not swung forward, and forms an angle close to 90° with respect to the ground G. The motion is such that the thigh bone <b>21</b> is lifted in synchronization with a velocity at which the user tries to go forward, but when this velocity at which thigh bone <b>21</b> is lifted is slow, the user stumbles over the step. The stumbling is likely to occur when the state shifts from the state <b>43</b> to the state <b>44</b>.

0044In the state <b>43</b>, the shoe has already departed from the ground G, as compared with the state during the normal walking. Thus, the microprocessor <b>14</b> receiving the signal from the acceleration sensor <b>13</b> determines that the trajectory of the shoe has changed, and instantly determines that the user has started a motion of overriding the step S to start scanning by the ranging sensor <b>10</b>.

0045The trajectory of the foot changes smoothly when it has not landed, and if the acceleration in the direction parallel to the ground and the acceleration in the direction perpendicular to the ground can be sensed, the trajectory of the shoe several milliseconds to several ten milliseconds after this time point can be predicted.

0046When the ranging sensor <b>10</b> senses the step (or an obstacle) S within several ten cm (for example, about 20 cm), the microprocessor <b>14</b> instantly calculates a collision time with the step S, based on the predicted trajectory. When a distance between the step S and the shoe is reduced as predicted after a predetermined time has passed, the microprocessor <b>14</b> determines that the user will stumble, and activates the stimulator <b>11</b> to stimulate the bottom of the foot of the user. The user reflexively lifts the foot by the stimulation given to the bottom of the foot, thereby avoiding the stumbling.

0047<figref idref="DRAWINGS">FIG. 5</figref> shows an example of processing algorithm of the microprocessor <b>14</b>. Before the walking is started, the microprocessor <b>14</b> enters the standby state to prevent consumption of the battery. When the signal is inputted from the pressure-sensitive sensor <b>12</b> (F<b>1</b>), the microprocessor <b>14</b> returns from the standby state and enters the activated state (F<b>2</b>). Next, the microprocessor <b>14</b> starts the sensing of the signal from the acceleration sensor <b>13</b> (F<b>3</b>) to put data of every walking cycle together to determine a walking mode (F<b>4</b>). One cycle of the walking can be decided by monitoring the signal of the pressure-sensitive sensor <b>12</b>. The walking mode includes, for example, a normal walking mode and a step ascent mode. In the case of the step ascent mode, since the trajectory of the shoe is different from the trajectory during the normal walking, as shown in <figref idref="DRAWINGS">FIG. 4</figref>, the mode can be easily determined by obtaining the trajectory of the shoe based on the signal from the acceleration sensor <b>13</b>.

0048When determined that it is the normal walking mode, stumbling determination is then carried out (F<b>5</b>). This stumbling determination is to determine if there is a possibility that a bottom of the shoe going forward scrapes the ground, although there is only little step ahead, and the user falls forward. This determination is enabled, for example, by calculating the lifting velocity and/or the lifting amount of the shoe from the signal of the acceleration sensor <b>13</b>, and by comparing the value with a reference value. The lifting amount can be obtained by integrating the lifting velocity. The reference value may be a fixed value set in advance, but for example, data of the lifting velocity or the lifting amount of the foot may be accumulated after the shoe <b>1</b> is started to be used, and the reference value may be decided from an average value or a statistical value of the accumulated data. If the lifting velocity and/or the lifting amount is lower than the reference value, the microprocessor <b>14</b> determines that there is a possibility that the user stumbles, and activates the stimulator <b>11</b> (F<b>6</b>). Since the walker reflexively lifts the foot by the stimulation given to the bottom of the foot, the stumbling is avoided. If it is determined in the stumbling determination (F<b>5</b>) that there is no possibility of stumbling, the processing returns to the sensing of the signal of the acceleration sensor <b>13</b> (F<b>3</b>) without actuating the stimulator <b>11</b>. In the normal walking mode, the ranging sensor <b>10</b> need not be actuated, and the processing can be simplified.

0049On the other hand, if the step ascent mode is determined in the walking mode determination, the signal of the ranging sensor <b>10</b> is acquired as shown in <figref idref="DRAWINGS">FIG. 6</figref> (F<b>7</b>) to measure the distance between the shoe <b>1</b> and the step (or the obstacle) S. Subsequently, collision determination is performed (F<b>8</b>). In the collision determination, the trajectory T of the shoe is calculated based on the detection signal of the acceleration sensor <b>13</b>, and the collision time with the step S is instantly calculated from the calculated trajectory T and the measured distance. Based on these calculation results, for example, if the distance between the step S and the shoe is reduced after the predetermined time has passed, it is determined that there is a possibility that the shoe collides, and the stimulator <b>11</b> is immediately actuated (F<b>6</b>). When determined that the shoe will not collide, the processing returns to the sensing of the signal of the acceleration sensor <b>13</b> without actuating the stimulator <b>11</b> (F<b>3</b>), and loop processing is repeated until it is determined that the signal of the acceleration sensor <b>13</b> is not present for a predetermined period. When determined that the signal of the acceleration sensor <b>13</b> is not present for the predetermined time, the microprocessor <b>14</b> enters the standby state (F<b>9</b>). In <figref idref="DRAWINGS">FIG. 5</figref>, although the standby determination is performed in the walking mode determination as well, whether or not the microprocessor <b>14</b> should shift to the standby state may be determined in a step different from the walking mode.

0050In the processing algorithm in <figref idref="DRAWINGS">FIG. 5</figref>, the example has been described in which the walking mode is determined based on the signal from the acceleration sensor <b>13</b>, and when determined as the normal walking mode, the signal from the ranging sensor <b>10</b> is not utilized. However, the signal from the ranging sensor <b>10</b> may be detected in the normal walking mode. For example, although there is some obstacle in front of the shoe, the walker may not notice the obstacle, and thus, when determined that the shoe will obviously collide with the obstacle, the microprocessor <b>14</b> may actuate the stimulator <b>11</b>.

0051<figref idref="DRAWINGS">FIG. 7</figref> shows an example of another processing algorithm of the present invention. While steps F<b>1</b> to F<b>3</b> are the same as those in <figref idref="DRAWINGS">FIG. 5</figref>, after the signal of the acceleration sensor <b>13</b> is acquired, only the stumbling determination is performed without determining the walking mode (F<b>5</b>). As a method of the stumbling determination, the lifting velocity and/or the lifting amount of the shoe may be calculated based on the signal from the acceleration sensor <b>13</b> to be compared with reference value, as in the foregoing. Further, the forward velocity of the shoe and the inclination angle of the shoe may be detected to be compared with reference values. In this case, since the ranging sensor <b>10</b> is not required, the circuit and the processing can be simplified.

0052Normally, the stumbling on a flat road, a step, stairs occurs because of slight insufficiency of the lifting amount of the shoe. Generally, the insufficiency is about 2 cm. Precise measurement is not required as to how much the shoe needs to be lifted to avoid the foregoing. Receiving the slight stimulation to the bottom of the foot causes the foot to be reflexively lifted by several centimeters, which allows the stumbling to be easily avoided.

0053In the above-described embodiment, only one of the shoes has been described, but the microprocessors each having a communication function may be included in both right and left shoes, and difference between the signals of the right and left shoes may be obtained to perform step determination. Synchronizing both the shoes also enables the walking abnormality to be detected. Furthermore, walking history data may be accumulated in the memory, and this data can be fetched so that walking history can be managed by a personal computer or the like. In the above-described embodiment, the pressure-sensitive sensor has been used as a trigger to activate the microprocessor, but for example, an ON/OFF switch may be provided in the shoe, and the microprocessor may be activated by operating this switch. Moreover, by one signal sensing of the pressure-sensitive sensor, the past processing may be reset to restart the processing.

DESCRIPTION OF REFERENCE SYMBOLS

0000<ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0000"><ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0054"><b>1</b> shoe body</li><li id="ul0002-0002" num="0055"><b>2</b> foot</li><li id="ul0002-0003" num="0056"><b>10</b> ranging sensor</li><li id="ul0002-0004" num="0057"><b>11</b> stimulator</li><li id="ul0002-0005" num="0058"><b>12</b> pressure-sensitive sensor</li><li id="ul0002-0006" num="0059"><b>13</b> acceleration sensor</li><li id="ul0002-0007" num="0060"><b>14</b> microprocessor</li><li id="ul0002-0008" num="0061"><b>15</b> battery</li><li id="ul0002-0009" num="0062"><b>16</b> wiring</li></ul></li></ul>