JP4724832B2 - Walking assistance control method and walking assistance control device - Google Patents

Description

The present invention relates to a walking assist control device and a control method thereof for a movement handicapped person (lower leg movement handicapped person) who cannot move the lower limb with his own power and who is difficult to walk.

  There is a device that assists the walking movement of a person with lower limb function such as an elderly person. (For example, Patent Document 1 and Patent Document 2). There is a device that reconstructs the lost gait function for those who have paralysis in both lower limbs due to spinal cord injury. (For example, Patent Document 3, Patent Document 4, and Patent Document 5).

JP 2000-166997 A JP 2004-329520 A Japanese Patent Application Laid-Open No. 07-222810 JP 2005-013534 A JP 2005-73935 A

For example, in the walking assist device for elderly people with lower limb function described in Patent Literature 1 and Patent Literature 2, the lower limb motion performed by the user is detected, and the power is controlled to assist the motion. However, this method cannot be applied to persons with lower limb movement disorders who are difficult to move their legs. Further, for example, in the devices described in Patent Literature 3, Patent Literature 4, and Patent Literature 5, lower limb motion is programmed in advance, and the lower limb is controlled using a switch or plantar pressure as a trigger. These devices have a problem that there is no means for inputting the stride and the exercise time that characterizes the movement of the lower limb in the walking motion, and the user cannot adjust the movement of the lower limb. In order for a person with lower limb movement disabilities to adjust the movement of the lower limb in real time, a means for inputting parameters of the stride and the exercise time characterizing the movement of the lower limb to the control device is necessary.

As a method for inputting the moving distance, there is a method in which acceleration data obtained from the acceleration sensor is converted into position data by twice integration processing and the moving distance is input. However, since the acceleration sensor is strongly affected by mechanical disturbances and is affected by temperature drift, the accuracy of the position data obtained by the double integration is low. Therefore, when the movement distance obtained from the position data calculated by this method is input to the walking assist control device, there is a problem in that it may cause a step that is not intended by a person with lower limb movement disorder due to an error and may cause a fall. .

  It is an object of the present invention to provide a control device and a control method for a lower limb exercise assisting device that enables a disabled person who is difficult to move the lower limb himself to adjust the stride and exercise time in lower limb exercise. To do.

A first aspect of the present invention is a walking movement assist control device that is attached to both lower limbs of a person with lower limb movement disorder who has movement disorders in both lower limbs, and a long lower limb orthosis that is attached to both lower limbs, and a hip joint of the long lower limb orthosis A controllable power attached to the hip joint; a first sensor capable of detecting movement of the hip joint attached to the hip joint; And a control device that controls the power, the control device calculates the state of the hip joint by the first sensor, and based on the measurement data by the second sensor A control device for calculating a power control command, a means for determining a movement distance and an exercise time of the hand from the data of the second sensor, and a target trajectory of the hip joint angle from the movement distance and the exercise time. Means and It is characterized in that a control means and means for determining a control command to the power to realize the target trajectory.

The second invention is the walking motion assist control apparatus according to claim 1, wherein the second sensor is characterized in that an acceleration sensor.

According to a third aspect of the present invention, in the walking motion assisting control device according to claim 2 , the control device further includes a determination unit for arm movement time, and the determination unit is configured to select an arm from the data of the acceleration sensor. It is a determining means comprising means for detecting that exercise has occurred, means for detecting the start time of arm movement, and means for detecting the end time of arm movement.

According to a fourth aspect of the present invention, in the walking movement assist control apparatus according to claim 3 , the control apparatus further includes means for determining a movement distance of the arm movement, and the means is a time range in which the arm movement occurs. This is a means for determining the movement distance of the arm movement by performing polynomial approximation on the acceleration data in, under the boundary condition that the speed and acceleration of the movement start time and end time are zero. .

The configuration of the walking assist control device of the present invention will be described with reference to FIG. A sensor 101 that measures the motion of a part (residual part) that a person with lower limb movement disorder can move by himself / herself is attached to the remaining part of the person with lower limb movement disorder. The motion sensor 101 of the remaining part is connected to the control device 102, and the motion data 105 of the remaining part is sent to the control device. The control device 102 is connected to power for moving the lower limbs, and a control signal 106 for controlling the power is transmitted to the power. A sensor 104 capable of measuring the movement of the lower limb caused by power is connected to the control device 102, and movement data 107 of the lower limb is sent to the control device 102.

A procedure for determining a control signal in the arithmetic unit of the walking assist control device of the present invention will be described with reference to FIG. First, in S201, motion data of a remaining part is input. In S202, it is determined whether or not the remaining part is in motion from the motion data of the remaining part. If it is determined that it is not exercising, the process returns to S201, and if it is determined that it is exercising, the exercise time of the remaining part is calculated in S203. Next, the moving distance of the remaining part is calculated in S204. In S205, a target trajectory for controlling the power of the lower limb is calculated from the movement distance and the exercise time. In S206, a control command for following the target trajectory is calculated. The control command calculated in S207 is output to the power. In S208, the end condition of the lower limb movement control is determined. If the end condition is not satisfied, the process returns to S206. If the end condition is satisfied, the walking end condition is determined in S209. If the end condition is not satisfied, the process returns to S201, and if the end condition is satisfied, the program ends.

In the present invention, as a means for measuring the motion of the remaining part of the person with lower limb movement disorder, the arm movement of the person with lower limb movement disorder is measured by an acceleration sensor. A method for detecting the time range in which the movement of the remaining part is performed from the acceleration data of the acceleration sensor will be described with reference to FIG. The method for detecting the time range of the exercise includes a method for detecting that the exercise is occurring, a method for detecting the exercise end time (end point), and a method for detecting the exercise start time (start point).

ここで、（数１）の条件は加速度が十分０に近い値である３０７の第２閾値a_th2よりも低い値であることを判別する条件である。（数２）の条件は加速度が極小であることを判別する条件である。（数３）は加速と減速の間にあるゼロクロス点３０５を誤検出してしまうことを防ぐための条件である。Dは最初に検出された加速度の方向と反対方向を表わす係数で、運動検出時の加速度の方向に対して逆向きの加速度の最大値が３０６の第１閾値a_th1を超えていることを判別することによって誤検出を回避する。始点の検出は終点の検出の後に行う。始点は運動検出時刻から時間逆向きに（数１）の条件と（数２）の条件を満たす時刻とする。この処理から、腕運動の開始と終了の時刻を特定し、腕運動に要した時間を特定する。 First, for motion detection, the time i when the acceleration data 301 exceeds the first threshold value a _th1 of 306 is set as the motion detection time 302, and the acceleration data at this time is set as a _i . Next, the time j of the end point 303 is detected as time passes. The time j of the end point 303 is a time that satisfies the following three conditions.

Here, the condition of (Expression 1) is a condition for determining that the acceleration is a value lower than the second threshold value a _{th2 of} 307, which is a value sufficiently close to zero. The condition of (Expression 2) is a condition for determining that the acceleration is minimal. (Equation 3) is a condition for preventing erroneous detection of the zero cross point 305 between acceleration and deceleration. D is a coefficient representing a direction opposite to the direction of acceleration detected first, and it is determined that the maximum value of acceleration in the opposite direction to the direction of acceleration at the time of motion detection exceeds the first threshold value a _th1 of 306. By doing so, false detection is avoided. The start point is detected after the end point is detected. The starting point is a time that satisfies the conditions of (Equation 1) and (Equation 2) in the reverse direction of the time from the motion detection time. From this process, the start and end times of the arm movement are specified, and the time required for the arm movement is specified.

  A method for determining the movement distance from the acceleration data between the start point and the end point of the motion in the present invention will be described. Since the tip of the cane during walking with a cane and the hand position during parallel bar walking are stationary at the start and end of arm movement, the speed and acceleration are zero. However, the value of the end point of speed obtained by mechanical disturbance or noise does not become zero because integration error accumulates. A large error may occur in the position data obtained by further integrating the velocity data. In the present invention, the position of the tip of the hand or cane is expressed by a polynomial, and the coefficient of the polynomial is determined from the measured acceleration data under the boundary condition that the velocity and acceleration of the start point and end point are 0, The moving distance is determined using a polynomial.

ここで、 k=1、2、…Nは時系列の番号を表わす。次に始点の位置を０とすると位置、速度、加速度に関する始点と終点の境界条件はそれぞれ（数７）と（数８）のように表わされる。

（数７）と（数８）の条件を（数６）に代入すると次式が得られる。

（数９）および（数１０）を（数６）の加速度の多項式に代入すると次式が得られる。

If the position of the tip of the hand or cane is expressed by an n-th order polynomial, the position can be expressed as (Equation 4). The speed can be expressed as (Equation 5). The acceleration can be expressed as (Equation 6).

Here, k = 1, 2,... N represents a time-series number. Next, assuming that the position of the starting point is 0, the boundary conditions of the starting point and the ending point regarding the position, speed, and acceleration are expressed as (Equation 7) and (Equation 8), respectively.

Substituting the conditions of (Equation 7) and (Equation 8) into (Equation 6) gives the following equation.

Substituting (Equation 9) and (Equation 10) into the acceleration polynomial of (Equation 6) gives the following equation.

から、最小二乗法によって５次からｎ次までの多項式の係数を決定する。多項式の係数は（数１３）により決定される。

決定された５次からｎ次までの多項式の係数を（数１０）に代入することにより４次および３次の多項式係数が得られる。特定された３次からｎ次の多項式係数と腕運動の時間を（数４）の位置を表わす多項式に代入することによって移動距離が得られる。 Next, a method for calculating the movement distance based on (Equation 4), (Equation 10), and (Equation 11) will be described. Acceleration described in (Equation 11) and acceleration measured by an accelerometer

Then, the coefficients of the 5th to nth order polynomials are determined by the least square method. The coefficient of the polynomial is determined by (Equation 13).

By substituting the determined polynomial coefficients from the fifth order to the nth order into (Equation 10), fourth order and third order polynomial coefficients are obtained. The movement distance is obtained by substituting the specified third-order to n-th order polynomial coefficients and the arm movement time into a polynomial representing the position of (Equation 4).

ここで、パラメータr₁ 、r₂ 、r₃ 、r₄は下肢運動障害者が使いやすいように調整される。 From the calculated movement time T _arm and movement distance D _{arm of the arm} movement, the movement time T _leg and the stride length D _leg of the lower limb movement are determined by the following conversion.

Here, the parameters r ₁ , r ₂ , r ₃ , r ₄ are adjusted so as to be easy to use for persons with lower limb movement disorders.

Next, a target trajectory for lower limb motion is generated from the data of the sensor for measuring the power state at the start of control, the stride D _leg, and the exercise time T _leg by using an appropriate interpolation method such as a spline. The control command is determined by performing the trajectory tracking control based on the data of the sensor that measures the target trajectory and the state of the power.

The arm movement time determining means of the present invention can be executed in real time from acceleration data. In the moving distance determination means based on the two-time integration, an error occurs in the speed obtained by the one-time integration due to the mechanical disturbance, and the speed at which the error has occurred is integrated. Since the moving distance determining means in the present invention performs polynomial approximation under the constraint that the end point speed is 0, the influence of this integration error can be reduced, and as a result, the moving distance accuracy sufficient for practical use is reduced. Is obtained.

According to the present invention, a person with lower limb movement disability adjusts the stride and lower limb movement time of the lower limb movement that cannot be moved by adjusting the movement time and movement distance in the movement of the arm that can be moved by itself. It becomes possible to do.

As an embodiment of the present invention, an apparatus for assisting a walking movement of a person with lower limb movement disorder in a parallel bar will be described with reference to FIGS. 4, 5, and 6. As a power mechanism capable of controlling the lower limb, for example, a long lower limb orthosis described in JP-A-11-222070 and its joint mechanism are assumed, and a lower limb movement disabled person 501 drives a hip joint including a DC motor 504 and a potentiometer 505. Wear a long leg brace 506 with a possible mechanism attached to the leg. Both hands hold an object 530 to which acceleration sensors 503 and 513 are attached, and plantar pressure sensors 507 and 517 are attached to the sole. The lower limb movement disabled person 501 wears an AD converter 508, a computer 509 having a calculation function and a storage function, a motor driving device 510, and a backpack 502 containing a battery 511. The acceleration sensors 503 and 513 of both arms are connected to the AD converter 508 via cables 521 and 522, respectively. The plantar pressure sensors 507 and 517 are connected to the AD converter 508 via cables 524 and 525, respectively. A hip potentiometer 505 is connected to an AD converter 508 via a cable 523. The AD converter 508 is connected to the computer 509. The computer 509 is connected to the driving device 510. A battery 511 is connected to the driving device 510. The driving device is connected to the DC motor 504 via the cable 520.

Next, the operation of the walking assist control device in the present embodiment will be described. The acceleration of the hand position, the output of the acceleration sensor, the output of the sole pressure sensor, and the output of the potentiometer are recorded in the storage device of the computer by AD conversion. When the lower limb movement handicapped person moves the arm forward together with the object to which the acceleration sensor is attached, the movement distance and movement time of the arm movement are calculated from the acceleration data by the movement time determination means and the movement distance determination means of the present invention. The stride and exercise time of the lower limb are determined from the movement distance and exercise time of the exercise. Determine the hip displacement required to execute the determined stride. The hip joint angle before exercise is calculated from the output of a potentiometer attached to the hip joint drive device. The hip joint angle at the end of the exercise is determined by adding the angle of displacement necessary to achieve the stride to the hip joint angle before the exercise. The target trajectory of the hip joint angle is determined by the fifth-order spline interpolation method called the jerk minimum trajectory from the hip joint angle before and after the lower limb motion and the motion time.

After the target trajectory is calculated, a power control command is calculated by trajectory tracking control using the target trajectory and the hip joint angle obtained from the potentiometer. The control command is output to the DC motor driving device. The drive device supplies battery power to the DC motor in accordance with the control command, and the hip motor moves when the DC motor rotates. As a result, the movement of the lower limb of the lower limb movement disorder person moves according to the target trajectory reflecting the movement time and movement distance set from the movement of the arm. When it is detected from the output of the sole pressure sensor that the sole touches the floor, the control of the lower limb is completed.

An experiment conducted to show that the determination method of the movement distance of the arm movement is more effective than the determination method based on the two-time integration and the result will be described. In the same manner as in the above example, the arm motion was measured and the arm motion was performed on the balance rod, and the arm motion was measured at a sampling frequency of 200 Hz using an acceleration sensor and a three-dimensional position measurement device. Marks were placed at positions where the arm movement was started and at positions 20, 30, 40, 50, and 60 cm away from the start point, and arm movement was performed 10 times from the start point to each mark.

The relation of the movement distance obtained by performing the integration twice from the acceleration sensor data with respect to the movement distance obtained from the position measuring device is shown in the upper part of FIG. Compared to the actual moving distance obtained from the position measuring device, the moving distance by numerical integration has a large error. The relationship between the movement distance obtained by performing polynomial approximation from the acceleration sensor data with respect to the movement distance obtained from the position measuring device is shown in the lower part of FIG. Compared to the numerical integration method, the error is small, and it can be confirmed that the moving distance can be calculated stably and accurately. The reason for the large error in the two-time integration method is that the error occurred in the first half of the motion caused by an error in the speed obtained by the one-time integration, and the error was accumulated. by. Since the moving distance determining means in the present invention performs polynomial approximation under the constraint that the end point speed is 0, the influence of this integration error can be reduced, and as a result, the moving distance accuracy sufficient for practical use is reduced. Is obtained.

Examples of the above embodiment will be described. In this embodiment, an approximation method using a seventh-order polynomial is applied to the calculation of the movement distance of the arm movement. The parameters r ₁ , r ₂ , r ₃ and r ₄ were set to 1, 0, 1.5 and 0, respectively. PID control was applied as a method of track tracking control. The sampling frequency of feedback was 300 [Hz].

  The data flow in the above embodiment will be described with reference to FIG. The arm motion is detected by the change in the left arm hand acceleration data 801, and the hip joint angle data 804 is displaced in the negative direction according to the target trajectory 803 calculated thereafter, and it is confirmed that the left leg motion has occurred. it can. Next, the arm motion is detected by the change in the hand acceleration data 802 of the right arm, and the hip joint angle data 804 is displaced in the positive direction, so that it can be confirmed that the right leg motion has occurred.

Comparing the amplitude of the change portion of the left arm acceleration data 801 and the change portion of the right arm acceleration data 802, it can be confirmed that the right arm acceleration data 802 is larger. This reflects that the movement distance of the arm is larger for the right arm. Looking at the next hip joint angle data 804, it can be confirmed that the displacement is larger when the right leg is moved than when the left leg is moved. Therefore, in this embodiment, it can be confirmed that it is possible to adjust the movement of the lower limb that cannot be moved according to the movement distance of the arm that the person with lower limb movement disability can move.

INDUSTRIAL APPLICABILITY The present invention can be used as a medical / welfare device that enables a movement handicapped person who cannot move his / her lower limbs to walk.

It is a figure which shows the structure of the walking assistance control apparatus which concerns on this invention. It is a figure which shows the flowchart in the walk assistance control apparatus which concerns on this invention. It is a figure explaining the method of determining the time range of the arm exercise | movement of a leg movement handicapped person from the acceleration data in the walking assistance control apparatus which concerns on this invention. It is a figure which shows the example of a structure of an apparatus as an example of embodiment in the walking assistance control apparatus which concerns on this invention. It is a figure which shows the example which the lower-limbs movement handicapped person wore the apparatus as an example of embodiment in the walking assistance control apparatus which concerns on this invention. It is a figure which shows the example of the mechanism for measuring the arm movement of the leg movement handicapped person in a parallel bar with an acceleration sensor as an example of embodiment in the walking assistance control apparatus which concerns on this invention. It is a figure explaining that the method by a polynomial approximation has a higher precision than the method by a 2nd-order integral as a means to determine the movement distance of the arm movement in the walk auxiliary control device concerning the present invention. FIG. 4 is a diagram showing acceleration data of arm motion, a target trajectory of a hip joint angle, and an actual trajectory of a hip joint angle as an embodiment in the walking assist control device according to the present invention.

Explanation of symbols

101 Sensor 102 that can measure the movement of the remaining part 103 Control device 103 Sensor 104 that can measure the movement of the lower limb generated by the power 104 Power of the lower part 108 Motion signal S201 of the lower limb generated by the movement signal 106 Control signal 107 of the remaining part Residual site motion data input unit S202 Residual site motion detection unit S203 motion time calculation unit S204 travel distance calculation unit S205 target trajectory calculation unit S206 control command calculation unit S207 control command output unit S208 lower limb control end condition determination unit S209 Condition determination unit 301 Acceleration data 302 Time at which motion was detected 303 Time at which end of motion was detected Time 304 Time at which start of motion was detected 305 Zero cross point 306 First threshold 307 Second threshold 501 Lower limb movement disorder 502 Backpack 503 Acceleration sensor 504 DC motor 505 points 506 Meter 506 Lower limb orthosis 507 Plantar pressure sensor 508 AD converter 509 Computer 510 Motor drive unit 511 Battery 513 Acceleration sensor 517 Plantar pressure sensor 520 Drive unit and DC motor cable 521 Acceleration sensor and AD converter cable 522 Acceleration sensor Cable 523 potentiometer to connect AD converter and cable 524 potentiometer to AD converter cable 524 Cable to connect plantar pressure sensor and AD converter 525 Cable to connect plantar pressure sensor and AD converter 530 Cylindrical for holding accelerometer The object 531 is a base 532 for placing the acceleration sensor on the cylindrical base, the parallel bar 801 is the acceleration sensor data 802 held on the left hand, the acceleration sensor data 803 is held on the right hand, the target trajectory 804 is the actual trajectory of the power

Claims (4)

This is a walking movement assist control device that is attached to both lower limbs of people with lower limb movement disorders who have movement disorders in both lower limbs, and can be controlled attached to the lower leg orthosis that is attached to both lower limbs and the hip joint of this long lower limb orthosis And a first sensor capable of detecting the movement of the hip joint mounted on the hip joint, and a second sensor mounted on both arms of the lower limb movement handicapped and capable of measuring the movement of both arms. A sensor and a control device for controlling the power, wherein the control device calculates a state of a hip joint by the first sensor and calculates a control command for the power based on measurement data by the second sensor a control device which comprises means for determining a movement distance and movement time of the hand from the data of the second sensor, and means for determining a desired trajectory angle of the hip joint from the moving distance and exercise time, the target trajectory Walking motion assist control apparatus characterized by comprising a means for determining a control command to the power to realize. The walking motion auxiliary control device according to claim 1, wherein the second sensor is an acceleration sensor. The control device further includes a determination unit for arm movement time, and the determination unit detects, from the data of the acceleration sensor, a unit for detecting that arm movement is occurring and a start time of the arm movement. The walking motion assisting control device according to claim 2 , wherein the walking motion assisting control device is a determining unit including a unit for performing arm movement and a unit for detecting an end time of arm movement. The control device further includes means for determining a movement distance of the arm movement, and the means is acceleration data in a time range in which the arm movement occurs, and the speed and acceleration at the movement start time and end time are 0. The walking motion assisting control device according to claim 3 , wherein the walking motion assisting control device is means for determining a movement distance of the arm motion by performing polynomial approximation under boundary conditions.

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