JP5177070B2 - Wearable measuring device and walking assist device - Google Patents

Description

  The present invention relates to a wearable measurement device that is mounted on one leg of a user and measures the relative position of the other foot with respect to the position of one foot, and a walking assist device that applies the measurement technique. The walking assist device assists the walking motion by applying torque to the leg joints of the user by a device with an actuator that is worn on one leg of the user. In this specification, in order to distinguish each leg of the user, one leg may be referred to as a first leg and the other leg may be referred to as a second leg. Further, in this specification, “foot” means a portion ahead of the ankle joint, and is used separately from “leg” including the thigh and the lower leg.

  So-called powered suits have been developed that are worn along the user's legs and arms to enhance the user's muscle strength. As an application of the powered suit, there is a walking assist device that is attached to a user's leg and assists walking motion. In one form of walking assist device, a leg brace having a multi-link mechanism with an actuator is worn from the user's thigh to lower leg, and the actuator applies torque to the leg to assist the walking motion. For example, Patent Literature 1 discloses a walking assistance device that attaches a leg brace with an actuator to each user's leg and assists the walking motion of both legs. Patent Document 2 discloses a walking assist device that attaches a leg brace with an actuator only to one leg of a user and assists the operation of the one leg.

JP 2003-135543 A JP 2006-314670 A

  Since the walking movement is a coordinated movement of both legs, it is necessary to assist the movement of the other leg according to the movement of one leg. Therefore, it is desirable to be able to detect and refer to the physical state of the second leg when assisting the operation of the first leg. Since the walking assist device of Patent Literature 1 attaches the brace to both legs of the user, a sensor for detecting the physical state of the leg may be attached to each brace. In the walking assistance device of Patent Document 2, it is necessary to wear a leg brace with an actuator on the first leg and to wear a leg motion detection brace on the second leg. In this specification, the “physical state of the leg” means the joint angle of the leg or the position of the foot.

  A walking assistance device for a user who is disabled only on one leg only needs to be equipped with a device with an actuator only on the disabled leg. As in the walking assist device of Patent Document 2, it is troublesome for the user to attach a leg motion detection device to the other leg. There is a demand for a technique that can measure the state of the other leg from the sensor of the brace attached to the first leg without attaching a sensor or the like to the second leg.

  The present invention has been created in view of the above problems. One of the present invention measures the relative position of the foot of the second leg with respect to the position of the foot of the first leg from the sensor of the appliance attached to the first leg without attaching a sensor or the like to the second leg of the user. A wearable measuring device is provided.

  As will be described later, the present invention measures the position of the leg of the second leg using a camera fixed to a leg brace attached to the first leg as a sensor. When a camera is used for measurement, a deviation in the fixed position of the camera causes a measurement error. It is not preferable to control the leg brace based on the measurement value including a large error. In particular, since the leg brace cannot be attached to the leg using a bolt or the like, there is a possibility that the attaching position with respect to the leg may be shifted during use. Another aspect of the present invention provides a walking assist device that stops an actuator when the mounting position of a leg brace with an actuator is shifted.

  One aspect of the present invention can be embodied in a wearable measurement device that is worn on the first leg of the user and measures the relative position of the foot of the second leg with respect to the foot position of the first leg. The apparatus includes a leg device of a multi-link mechanism attached to a first leg, an angle sensor for detecting an angle of each joint of the leg device, a camera fixed to the leg device, an output of the angle sensor, and a camera image. And a controller for calculating a relative position of the foot of the second leg with respect to the position of the foot of the first leg. In the leg brace, the distal end link is fixed to the leg of the first leg, and the other link group is attached along the first leg. Further, in the leg brace, each link connected by the rotary joint swings in accordance with the movement of the first leg. The camera is attached to the leg brace in an arrangement capable of photographing the second leg. More specifically, the camera is fixed to one of the other link groups. The controller executes the following first calculation, second calculation, and third calculation. In the first calculation, the relative position of the foot of the first leg with respect to the camera position is calculated based on the joint angle detected by the angle sensor. In the second calculation, the relative position of the leg of the second leg with respect to the camera position is calculated based on the image obtained by photographing the second leg. In the third calculation, the relative position of the foot of the second leg with respect to the foot position of the first leg is calculated based on the results of the first calculation and the second calculation.

  In this wearable measuring apparatus, a camera for photographing the second leg is fixed to a leg brace attached to the first leg, and the relative position of the leg of the second leg with respect to the camera position is calculated by image processing based on the image of the camera. . The wearable measurement device of the present invention can measure the foot position of the second leg by using a camera without attaching a sensor or the like to the second leg. The foot position obtained from the camera image is a relative position with respect to the camera position. However, the measuring device according to the present invention allows the foot of the first leg with respect to the camera position from each joint angle of the leg brace attached to the user's first leg. The relative position of the second leg to the first leg is calculated by using the relative position of the first leg and the second leg relative to the camera position.

  It is also preferable to attach a known marker to the second leg so that the foot position can be easily calculated from the image. A technique for calculating the position of an object from an image by attaching a known marker to the object is a technique often used in the technical field of image processing. The “foot position” may be a fixed point in a coordinate system fixed to the foot. Such a fixed point is determined at the time of designing the leg brace. For example, the fixing point may be determined on the toe of the foot or may be determined on the heel of the foot. The “relative position of the foot with respect to the camera position” corresponds to “the coordinates of the foot in the camera-fixed coordinate system”.

  When the leg brace is attached to the user's first leg, a belt or the like is used. Therefore, there is a possibility that the relative position of the first leg and the leg brace may be shifted during use. If the relative position between the first leg and the leg brace is deviated, the relative position of the foot of the first leg with respect to the camera position, which is calculated based on the joint angle detected by the angle sensor, may include an error. In order to suppress an error that may occur in the measurement value of the foot position, the wearable measurement device of the present invention preferably includes the following technical features. That is, the above-described camera is fixed in an arrangement capable of photographing the first leg together with the second leg. On the other hand, the controller stores the initial fixed position of the camera relative to the first leg. The controller executes the following fourth calculation, deviation amount calculation, and correction calculation. In the fourth calculation, the relative position of the camera with respect to the first leg is calculated from the image of the first leg taken by the camera. In the deviation amount calculation, a positional deviation amount between the relative position calculated by the fourth calculation and the stored initial fixed position is calculated. In the correction calculation, the relative position of the foot of the second leg calculated by the third calculation is corrected by the amount of displacement. With the above technical features, it is possible to suppress the measurement error of the foot position caused by the relative positional deviation between the leg brace and the first leg.

  A measurement technique for measuring the physical state of the second leg without attaching a sensor or the like to the second leg is suitable for a walking assist device that assists only one leg. That is, without attaching a sensor or the like to the second leg, the walking motion of the first leg can be assisted in cooperation with the motion of the second leg only by the appliance with the actuator attached to the first leg. Here, the amount of positional deviation described above is useful for preventing troubles in assisting walking motion caused by mounting deviation of leg braces. Another aspect of the present invention can be embodied in a walking assist device including the above-described wearing type measuring device. The walking assist device includes an actuator that applies torque to the joint of the first leg, and the controller described above is an actuator when the amount of positional deviation calculated by the deviation amount calculation exceeds a threshold value. It is characterized by stopping. The walking assistance device having such technical features can stop the actuator when the attachment position of the leg brace with the actuator is shifted and the measurement error is expected to increase.

  According to the present invention, the attachment of measuring the relative position of the foot of the second leg with respect to the foot position of the first leg from the sensor of the leg brace attached to the first leg without attaching a sensor or the like to the second leg of the user. A mold measuring device can be realized. Furthermore, it is possible to realize a walking assist device that stops the actuator when the attachment position of the leg orthosis with the actuator is shifted.

The perspective view of a walk auxiliary device is shown. The perspective view of the walk auxiliary device in the state where the user wore was shown. The figure explaining the measurement algorithm of the relative position of a foot | leg is shown. The flowchart of a measurement process is shown.

  A walking assistance device 10 according to an embodiment will be described with reference to the drawings. In FIG. 1, the typical perspective view of the walking assistance apparatus 10 is shown. FIG. 2 shows a schematic perspective view of the walking assist device 10 in a state worn by the user. The walking assist device 10 is a device for a user who cannot move the left leg freely. The walking assist device 10 is attached to the user's left leg, and assists the user's walking motion by applying an appropriate torque to the user's left leg joint. The left leg corresponds to the first leg and the right leg corresponds to the second leg.

  Since the walking movement is realized by the coordinated movement of both legs, it is important to measure the movement of the other leg when the leg brace attached to one leg is controlled based on the movement of the other leg. In particular, the joint angle and foot position of the other leg are important. The position of the other foot need not be a position in the absolute coordinate system, as long as the relative position with respect to the foot position of one leg can be measured. The walking assistance device 10 according to the embodiment can measure the relative position of the leg of the other leg with respect to the position of the leg of one leg and the joint angle of the other leg by a sensor included in the leg brace attached to the one leg. There are features. Of the functions of the walking assist device 10, the part that executes the process of measuring the relative position of the foot corresponds to an example of a wearable measuring device. Below, after explaining the structure and function of the walking assistance apparatus 10, the measurement technique of the leg position and joint angle of the other leg will be described.

  The walking assist device 10 is worn from the thigh of the user's left leg to the foot. That is, the mechanism itself of the walking assist device 10 corresponds to the leg orthosis 12. Therefore, in FIGS. 1 and 2, reference numerals 10 and 12 indicate the same object. The leg orthosis 12 is configured by a multi-link mechanism having a thigh link 14, a crus link 16, and a sole link 18. The upper end of the thigh link 14 is connected to the support link 30 via the crotch joint 20a. The lower leg link 16 is connected to the thigh link 14 by a knee joint 20b located outside the knee. The sole link 18 is connected to the crus link 16 by an ankle joint 20c located outside the user's heel. The sole link 18 corresponds to the tip link of the leg orthosis 12. The support link 30 is fixed to the user's waist. The thigh link 14 is fixed to the user's thigh with a belt. The lower leg link 16 is fixed to the user's lower leg by a belt. The sole link 18 is fixed to the sole of the user with a belt. Note that belts other than the belt for fixing the sole link 18 are not shown.

  When the user wears the leg brace 12, the thigh link 14 is positioned outside the user's thigh, the crus link 16 is positioned outside the user's crus, and the sole link 18 is positioned on the sole of the user. To do. At this time, the crotch joint 20a, the knee joint 20b, and the ankle joint 20c are positioned adjacent to the user's hip joint, knee joint, and ankle joint, respectively. More specifically, when the user wears the leg brace 12, the hip joint 20a, the knee joint 20b, and the ankle joint 20c are respectively the pitch axis of the user's hip joint, the pitch axis of the knee joint, and the pitch of the ankle joint. Located coaxially with the shaft. The joints 20a, 20b, and 20c are rotary joints that relatively rotate two linked links. In the leg brace 12, each link swings in accordance with the movement of the user's left leg.

  Each joint 20a, 20b, and 20c includes an encoder 21 for detecting an angle between the links and a motor (actuator) that rotates the links. The encoder 21 corresponds to an angle sensor that detects the joint angle of the leg orthosis 12. In the figure, the illustration of the motor is omitted. The motor of the crotch joint 20 a rotates the thigh link 14 with respect to the support link 30. The motor of the knee joint 20 b rotates the crus link 16 with respect to the thigh link 14. The motor of the ankle joint 20 c rotates the sole link 18 with respect to the crus link 16. Note that the leg brace 12 in which each link swings by the motor corresponds to a leg brace with an actuator.

  A beam 40 extends forward from the upper end of the thigh link 14, and a camera 42 is fixed to the tip of the beam 40. In other words, the camera 42 is fixed to the thigh link 14 of the leg brace 12. As shown in FIG. 2, markers M1, M2, and M3 are attached to the thigh, lower leg, and foot of the user's right leg, respectively. On the other hand, a marker M4 is attached to the thigh of the user's left leg. The markers M <b> 1 to M <b> 4 have known shapes and are attached to make it easy to specify the position and posture of the legs by image processing. Note that the user's left leg is the leg to which the leg brace 12 is attached and the right leg is the leg to which the leg brace 12 is not attached. The camera 42 includes an ultra-wide-angle lens, and can photograph the markers attached to the right leg and the left leg. As will be described later, the walking assist device 10 measures the joint angle of the right leg and the position of the foot based on the marker image captured by the camera 42.

  The motor of each joint is controlled by a controller 32 attached to the support link 30. The controller 32 measures the joint angle and foot position of the right leg based on the joint angle of the leg brace 12 and the image of the right leg marker imaged by the camera 42. Then, the controller 32 controls the leg brace so that the handicapped left leg operates in coordination with the healthy right leg movement based on the measured joint angle and foot position of the right leg, and the user's walking motion is controlled. Assist. That is, the walking assistance device 10 controls the leg brace with an actuator so that one leg operates in cooperation with the operation of the other leg without attaching a sensor or the like to the other leg. Here, typical parameters representing the motion of the other leg are the joint angle of the other leg and the relative position of the leg of the other leg with respect to the foot position of the one leg. In addition, description is abbreviate | omitted about the specific control of the leg orthosis with an actuator. Regarding a walking assistance device that includes a leg brace with an actuator that is attached to one leg, and that controls the leg bracing so that one leg moves in cooperation with the movement of the other leg, for example, Please refer to Japanese Patent Application Nos. 2008-235463 and 2008-276309. Japanese Patent Application No. 2008-235463 and Japanese Patent Application No. 2008-276309 have not been disclosed at the time of filing this application.

  A method for measuring the joint angle of the right leg and the relative position of the right leg with respect to the position of the left leg will be described with reference to FIGS. The controller 32 of the walking assist device 10 measures the joint angle and the relative position of the foot based on the image of the camera 42 fixed to the leg brace 12 and the joint angle measured by the encoder 21.

  FIG. 3 shows a schematic side view of the walking assistance device 10 worn by the user. In FIG. 3, the geometric shape of the leg orthosis 12 shown in FIG. 1 is simplified for easy understanding of the drawing. FIG. 4 shows a flowchart of the measurement process. FIG. 4 includes not only the measurement process but also a motor stop process of the walking assist device 10. The stop process will be described later. The following description will be limited to the movement of the legs in the sagittal plane. “Sagittal plane” means a plane orthogonal to the pitch axis. In other words, the following description limits the movement of the leg to rotation about the pitch axis of the leg joint. Although the description is limited to the sagittal plane, the following description can be easily extended to a three-dimensional space.

  A new code used in FIG. 3 and the following description will be described. A symbol Ah represents an angle formed by the left and right legs of the user. This angle is referred to as a hip joint angle Ah. The symbol An represents the angle of the user's right knee joint. This angle is referred to as a right knee joint angle An. The symbol Aa represents the angle of the user's right ankle joint. This angle is referred to as a right ankle joint angle Aa. The symbol Pr represents a point fixed to the user's right foot. This point is referred to as a right foot reference point Pr. The symbol Pq represents a point fixed to the user's left foot. This point is referred to as the left foot reference point Pq. The right foot reference point Pr is determined in advance, and the position of the right foot is represented by the position of this point. The same applies to the left foot reference point Pq.

  A symbol Vcr represents a vector from the camera origin to the right foot position in the camera fixed coordinate system. This vector is referred to as camera / right foot vector Vcr. In other words, the camera / right foot vector Vcr represents the position of the right foot relative to the camera position. The symbol Vcq represents a vector from the camera origin to the left foot position in the camera fixed coordinate system. This vector is referred to as camera / left foot vector Vcq. In other words, the camera / left foot vector Vcq represents the relative position of the left foot to the camera position. A symbol Vqr represents a vector from the left foot position to the right foot position in the camera-fixed coordinate system. This vector is referred to as a left foot / right foot vector Vqr. In other words, the left foot / right foot vector Vqr represents the relative position of the right foot with respect to the left foot position. The left foot / right foot vector Vqr is a vector to be finally measured.

  A measurement method will be described. The fixed positions of the markers M1 to M4 on the user's body are stored in the controller 32 in advance. The controller 32 also stores an initial fixed position of the leg brace relative to the left leg. Since the camera 42 is fixed to the leg brace 12, in other words, the controller 32 stores the initial fixed position of the camera 42 relative to the left leg on which the leg brace 12 is mounted. More precisely, the controller 32 stores the initial fixed position of the camera 42 relative to the marker M4 attached to the left leg.

  The controller 32 acquires the angle of each joint of the leg orthosis 12 from the encoder 21 (S2). The controller 32 calculates the camera / left foot vector Vcq using the acquired joint angle (S4). Here, the sole link 18 (tip link) of the leg orthosis 12 is fixed to the left foot, and the joint angle from the thigh link 14 to which the camera 42 is fixed to the sole link 18 is acquired. Therefore, the controller 32 can calculate the camera / left foot vector Vcq from the joint angle by so-called forward kinematics calculation in robotics. This calculation corresponds to the first calculation.

  Moreover, the controller 32 acquires the image of the camera 42 (S6). Markers M1 to M4 are shown in the image. In other words, the controller 32 acquires an image obtained by photographing the right leg marker and the left leg marker. Next, the controller 32 specifies the position of each marker in the camera-fixed coordinate system (S8). Here, the expression “marker position” includes the inclination of the marker. Since the technique for identifying the position and inclination of a marker having a known shape from an image is well known in the technical field of image processing, detailed description thereof is omitted. The controller 32 calculates the hip joint angle Ah, the right knee joint angle An, and the right ankle joint angle Aa from the positions of the markers M1 to M3 attached to the right leg (S10). Here, the marker M1 is attached to the thigh of the right leg, and the position of the camera 42 with respect to the left leg is known. From these relationships, the controller 32 can calculate the relative position and inclination of the right leg thigh with respect to the camera position, and can determine the hip joint angle Ah from the relative position and inclination. Further, since the marker M2 is attached to the lower leg of the right leg, the position and inclination of the lower leg of the right leg are obtained from the image. Since the position and inclination of the thigh and crus of the right leg are obtained from the image, the controller 32 can calculate the right knee joint angle An from these values. Similarly, since the marker M3 is attached to the right foot, the controller 32 can calculate the right ankle joint angle Aa. Thus, the controller 32 calculates the joint angle of the right leg. Since the right leg geometry is known, the controller 32 performs forward kinematics calculations based on the right leg geometry and joint angles to determine the position of the right foot in the camera coordinate system, ie, the camera / right foot vector. Vcr is calculated (S12). Through the processes in steps S8, S10, and S12, the controller 32 calculates a camera / right foot vector Vcr from an image obtained by photographing the right leg. This calculation corresponds to the second calculation.

  The controller 32 uses the camera / left foot vector Vcq and the camera / right foot vector Vcr to calculate the left foot / right foot vector Vqr, that is, the relative position of the right leg to the left leg (S14). This calculation corresponds to the third calculation. The third calculation may be a vector calculation that subtracts the camera / right foot vector Vcr from the camera / left foot vector Vcq. As described above, the controller 32 obtains the relative position of the right leg to the left leg by the first calculation, the second calculation, and the third calculation.

  Next, the controller 32 calculates the relative position of the camera 42 with respect to the left leg from the image of the marker M4 attached to the left leg. This calculation corresponds to the fourth calculation. The controller 32 calculates a difference ΔV between the relative position calculated by the fourth calculation and the stored initial fixed position (S16). ΔV represents the amount of deviation of the camera 42 from the initial fixed position. The calculation in step S16 corresponds to a deviation amount calculation. Next, the controller 32 determines whether or not the deviation amount ΔV exceeds a predetermined threshold value (S18). The threshold value is stored in the controller 32 in advance. When the deviation amount ΔV does not exceed the threshold value, the controller 32 corrects the left / right foot vector Vqr with the deviation amount ΔV (S18: NO, S20). Specifically, the controller 32 adds the deviation amount vector ΔV to the vector Vqr calculated in step S14. The corrected vector Vqr represents an accurate foot position in which the shift amount ΔV of the leg appliance 12 is canceled. The controller 32 controls the motor of the leg orthosis 12 using the corrected vector Vqr. As described above, the description of the control of the leg appliance 12 using the vector Vqr is omitted.

  On the other hand, if ΔV exceeds the threshold, the controller 32 stops the control of the motor (S18: YES, S22). The case where ΔV exceeds the threshold is a case where the fixed position of the camera 42 with respect to the left leg is greatly deviated from the initial fixed position, that is, the position of the leg orthosis 12 with respect to the left leg is largely deviated from the initial fixed position. Means that When the left leg and the leg brace 12 are largely deviated, there is a possibility that the left leg cannot be properly assisted by driving the leg brace 12. Therefore, the motor is stopped to avoid inappropriate assistance. In other words, the walking assistance device 10 stops the actuator when the attachment position of the leg brace 12 with the actuator is shifted by a predetermined threshold value or more.

  In the description using FIG. 3, the movement of the legs is limited to the movement in the sagittal plane, but the above description can be easily extended to three dimensions. It is well known that each marker has six known feature points, and the three-dimensional position and orientation of the marker can be specified by specifying the positions of the six feature points by image processing. ing. Here, the “posture” means a rotation angle around each axis of three orthogonal axes, so-called roll, pitch, and yaw. Alternatively, even if each marker has three feature points, the three-dimensional position and posture of the marker can be obtained by providing two cameras on the leg brace. In that case, the three-dimensional position of each feature point of each marker is obtained by the principle of stereoscopic vision using two cameras fixed to the leg brace 12, and the posture of the marker is specified from the three-dimensional position of the three feature points. That's fine.

  In the embodiment, the walking assistance device 10 that is attached to one leg of the user and assists the movement of the one leg has been described. In the flowchart of FIG. 4, the walking assistance device 10 that executes other processing than step S22 that is a motor control processing corresponds to an example of a wearable measuring device.

  One of the technical features of the walking assist device 10 (wearable measurement device) can be expressed as follows. The walking assist device 10 includes markers M1, M2, M3, and M4 having known shapes for attaching to the first leg and the second leg. The markers M1, M2, and M3 are attached to the second leg, and the marker M4 is attached to the first leg. The controller 32 stores an initial fixed position of the camera 42 relative to the first leg marker M4. The camera 42 is fixed in an arrangement capable of photographing the first leg marker M4 together with the second leg markers M1 to M3. The controller 32 performs the following fourth calculation, shift amount calculation, and correction calculation. In the fourth calculation, the relative position of the camera 42 to the first leg marker M4 is calculated from the image taken by the camera 42. In the deviation amount calculation, a positional deviation amount ΔV between the relative position calculated by the fourth calculation and the stored initial fixed position is calculated. In the correction calculation, the relative position of the foot of the second leg calculated by the third calculation is corrected by the positional deviation amount ΔV.

  The points to be noted in the embodiment will be described. If the leg geometry is known, there is a unique relationship between the leg joint angle and the relative position of the foot relative to the hip position. The relative position of the foot can be determined. In the above embodiment, the joint angle of the right leg is obtained from the marker image, and the relative position of the foot is obtained from the joint angle by forward kinematics calculation. Conversely, if the relative position of the foot can be detected, the joint angle of the leg can be obtained by so-called inverse kinematics calculation. As a modified example of the embodiment, the relative position Vcr of the right foot with respect to the camera position is first obtained based on the image of the marker M3 attached to the right foot, and the joint angle of the right leg is obtained by inverse kinematics calculation from the relative position Vcr of the right foot. Good.

  Further, the walking assist device 10 of the embodiment employs a marker in order to facilitate image processing for obtaining the position and posture of the leg. The joint angles and foot positions of the legs may be obtained by image processing from the shape of the legs in the image without using a marker. Image processing is more complicated than using markers, but markers can be eliminated.

  In the embodiment, the relative position Vqr of the right foot with respect to the position of the left foot in the camera coordinate system was finally obtained. Since the geometry of the leg brace is known and the joint angle can be detected, it is easy to convert the vector Vqr from the camera coordinate system to a coordinate system fixed to any link of the leg brace. The controller can be used to control the leg brace 12 after converting the vector Vqr represented in the camera coordinate system into a coordinate system representation fixed to any link of the leg brace.

  A preferred modification of the apparatus of the embodiment will be described. You may employ | adopt the trousers in which the known figure was drawn as a marker. Known figures serve as markers. In this case, a known figure should be drawn on the entire pants. If a known figure is drawn on the entire pants, the marker can be prevented from being hidden in the blind spot of the camera.

  It is also preferable to employ a marker to which a fluorescent paint is applied. This is because image processing for identifying a marker is facilitated even in a dark environment.

  In addition to the camera for photographing the right leg marker, a second camera for photographing the left leg marker on which the leg brace is attached may be provided.

  The camera may use a CCD element or a CMOS element. Further, the camera may be a camera capable of photographing up to the infrared region. This is because image processing for identifying a marker is facilitated even in a dark environment.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

10: Walking assist device 12: Leg orthosis 14: Thigh link 16: Lower leg link 18: Sole link 20a, 20b, 20c: Joint 21: Encoder (angle sensor)
30: Support link 32: Controller 40: Beam 42: Camera

Claims (3)

A wearable measurement device that is mounted on a user's first leg and measures the relative position of the second leg with respect to the first leg.
A multi-link mechanism in which the distal link is fixed to the leg of the first leg and another link group is mounted along the first leg, and each link connected by the rotary joint swings in accordance with the movement of the first leg. Leg brace,
An angle sensor for detecting the angle of each joint of the leg brace;
A camera fixed to one of the other link groups and shooting the second leg;
A controller that calculates the relative position of the foot of the second leg with respect to the position of the foot of the first leg based on the angle of each joint of the leg brace and an image of the second leg,
The controller
A first calculation for calculating a relative position of the foot of the first leg with respect to the camera position based on the joint angle detected by the angle sensor;
A second calculation for calculating a relative position of the leg of the second leg with respect to the camera position based on an image obtained by photographing the second leg;
A third operation for calculating a relative position of the foot of the second leg with respect to the foot position of the first leg based on the results of the first operation and the second operation;
A wearable measuring device characterized in that The camera is fixed in an arrangement capable of photographing the first leg together with the second leg,
The controller stores an initial fixed position of the camera relative to the first leg, and calculates a relative position of the camera relative to the first leg from an image of the first leg captured by the camera;
A deviation amount calculation for calculating a positional deviation amount between the relative position calculated by the fourth calculation and the stored initial fixed position;
A correction calculation for correcting the relative position of the foot of the second leg calculated by the third calculation with the amount of displacement;
The wearable measuring apparatus according to claim 1, wherein: A walking assist device including the wearing type measuring device according to claim 2,
The leg brace includes an actuator that applies torque to the joint of the first leg,
The walking assist device according to claim 1, wherein the controller stops the actuator when the positional deviation amount calculated by the deviation amount calculation exceeds a threshold value.

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