KR102288885B1 - Method and system for controlling walking wearble robot at stairs - Google Patents

Abstract

a comparison step of comparing the height of the support leg and the swing leg when the robot supports one leg; and when the foot height of the support leg is higher than the foot height of the swing leg, an auxiliary torque application step of applying the stair walking assistance torque value to the support leg; and the swing leg touches the ground while the robot supports one foot, so that both feet are supported In this case, a repulsive torque application step of applying a ground repulsion torque value to the swing leg; a method and system for controlling stair walking of a wearable robot to perform are introduced.

Description

Method and system for controlling stair walking of a wearable robot

The present invention relates to a stair gait control method of a robot that can reduce the load and shock received by a wearer when walking stair by applying an algorithm for improving stair gait performance of a wearable robot.

Recently, robots have been actively used in all industries. A lot of research is being done on wearable robots that can be used by humans as well as robots that operate by themselves equipped with artificial intelligence.

The most core technology in such a wearable robot is to understand the wearer's intention of movement and to make the robot operate according to the wearer's intention. Therefore, various control methods for controlling the robot by grasping the intention of the wearer have been proposed.

However, these control methods are applied to walking in general situations, and are difficult to apply in special situations such as going up or down stairs.

In particular, in a wearable robot, when going up the stairs, more force is required as much as the weight of the robot, so the wearer feels the load more by that weight. Because the impact is applied to the leg, the impact is applied to the leg and joints.

The matters described as the above background art are only for improving the understanding of the background of the present invention, and should not be taken as acknowledging that they correspond to the prior art already known to those of ordinary skill in the art.

An object of the present invention is to provide a method for controlling stair walking of a wearable robot that can improve the walking performance of the robot by minimizing the burden and shock felt on the leg when a person wears the wearable robot and walks the stairs.

Step walking control method of a wearable robot according to the present invention for achieving the above object, when the robot supports one leg, a comparison step of comparing the foot height of the support leg and the swing leg; and when the foot height of the support leg is higher than the foot height of the swing leg, an auxiliary torque application step of applying a step walking assistance torque value to the support leg; may be performed.

In addition, when the swing leg is in contact with the ground in a state where the robot is supported on one leg and both feet are supported, a repulsion torque application step of applying a ground repulsion torque value to the swing leg; may be configured to perform.

The ground repulsion torque is calculated by multiplying the difference between the sum of the repulsion forces of the support leg and the swing leg and the sum of the weight of the robot and the person by the control constant, and can be derived by substituting the ground repulsion force into the Jacobian transposition matrix. .

The foot height of the support leg and swing leg is calculated using the angle value and static kinematics formed by each joint of the robot. .

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: 제어상수,

: 계단 보행 보조 힘, 계단 보행 보조 토크, J: 자코비안 행렬,

: 지지다리의 x축좌표, 스윙다리의 x축좌표, 지지다리의 발높이, 스윙다리의 발높이

: control constant,

: Stair walking aid force, Stair walking aid torque, J: Jacobian matrix,

: The x-axis coordinate of the support leg, the x-axis coordinate of the swing leg, the foot height of the support leg, the foot height of the swing leg

The stair gait control system of the wearable robot includes a support leg and a swing leg; and when the foot height of the support leg is higher than the foot height of the swing leg, a stair walking assist torque value is applied to the support leg. A control unit for applying a torque value; consists of.

The control unit of the stair walking control system of the present robot may perform a repulsion torque application step of applying a ground repulsion torque value to the swing leg when the swing leg touches the ground and supports both feet while the robot is supported on one foot.

The ground repulsion torque in the stair walking control system of the wearable robot is calculated by multiplying the difference between the sum of the repulsion forces of the support leg and the swing leg and the weight of the robot and the person by the control constant to calculate the ground repulsion force, and calculate the ground repulsion force. It can be derived by substituting it into the Cobian transposition matrix.

The foot height of the support leg and swing leg can be calculated using the angle value and the static kinematics formed by each joint of the robot.

The stair walking assistance torque value in the stair gait control system of the wearable robot can be derived by substituting the foot heights of the support legs and the swing legs into the following equations.

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,

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: 제어상수,

: 계단 보행 보조 힘, 계단 보행 보조 토크, J: 자코비안 행렬,

: 지지다리의 x축좌표, 스윙다리의 x축좌표, 지지다리의 발높이, 스윙다리의 발높이

: control constant,

: Stair walking aid force, Stair walking aid torque, J: Jacobian matrix,

: The x-axis coordinate of the support leg, the x-axis coordinate of the swing leg, the foot height of the support leg, the foot height of the swing leg

As described above, if the stair walking control method of the wearable robot is used, the following effects can be obtained.

First, when the wearer wears the robot and climbs the stairs, the stair walking assistance algorithm reduces the wearer's load by raising the supporting leg.

Second, when the wearer wears the robot and goes down the stairs, the ground reaction force control algorithm drastically reduces the impact between the ground and the robot swing leg.

Third, since it can be implemented only by adding the stair walking assistance algorithm and the ground reaction force control algorithm in the control unit without adding a separate device, there is no risk of cost increase due to the implementation of the present invention.

1 is a flowchart of a method for controlling stair walking of a wearable robot according to an embodiment of the present invention;
Figure 2 is a torque and force applied to the robot when the wearer climbs the stairs according to the embodiment of the present invention;
3 is a torque and force applied to the robot when the wearer goes down the stairs according to the embodiment of the present invention;
4 is a block diagram of a stair walking control system of a wearable robot according to an embodiment of the present invention;

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

As can be seen from FIG. 1, the present invention provides a comparison step (S200) of comparing the height of the foot of the support leg and the swing leg when the robot supports one leg (S100); And when the foot height of the support leg is higher than the foot height of the swing leg, an auxiliary torque application step (S300) of applying a stair walking assistance torque value to the support leg; to reduce the load of the wearer when the wearer climbs the stairs by performing; give.

Here, the comparison step (S200) of comparing the height of the foot of the support leg and the swing leg may be performed in various ways. However, in the present invention, a method of calculating the foot height of the support leg and the swing leg using the angle value formed by each joint of the robot and the static kinematics was used.

In a wearable robot, the joint of each robot is provided with devices such as an encoder that can measure the angle value of the joint. Therefore, using the measured joint angle value and regular kinematics, the position of the leg end can be calculated in the form of a three-dimensional Cartesian coordinate system. In general, the x-coordinate represents the front-back coordinates in the moving direction of the robot, the y-coordinate represents the left-right coordinates in the moving direction, and the z-coordinate means the up-and-down coordinates in the moving direction.

Therefore, by using the Cartesian coordinates calculated in the above manner, it is possible to compare the height of the feet of the support leg and the swing leg. As a result of the comparison, if the foot height of the support leg is higher than the foot height of the swing leg, the controller determines that the robot is going up the stairs, and the auxiliary torque application step (S300) is performed.

In FIG. 2 , when the wearer climbs the stairs, it is shown that the stair walking assistance torque is applied to the rotary actuator of each joint. The stair walking assistance torque value can be derived by substituting the foot height of the support leg and the swing leg into the following equation.

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,

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,

,

,

: 제어상수,

: 계단 보행 보조 힘, 계단 보행 보조 토크, J: 자코비안 행렬,

: 지지다리의 x축좌표, 스윙다리의 x축좌표, 지지다리의 발높이, 스윙다리의 발높이

: control constant,

: Stair walking aid force, Stair walking aid torque, J: Jacobian matrix,

: The x-axis coordinate of the support leg, the x-axis coordinate of the swing leg, the foot height of the support leg, the foot height of the swing leg

In the above formula, the x-axis coordinates and foot height of the support leg and swing leg can be calculated using the joint angle value and static kinematics as described above. The x-coordinate and z-coordinate of the stair walking assistance force can be obtained by multiplying the difference value of the robot by the control constant value.

로 계단 보행 보조 힘의 y축 행렬은 0으로 보았다.Here, it is not necessary to calculate the y-coordinate of the stair walking assistance force. Because, in general, when wearing a robot and going up stairs, the x-axis and z-axis coordinates correspond to the front-back and up-down coordinates of the robot's moving direction, so the values will change, but the y-axis coordinates correspond to the left and right coordinates of the robot's moving direction. Because it is safe to say that there is no change in the bar. Therefore, even in the formula for calculating the stair walking assistance force

As a result, the y-axis matrix of the stair walking assistance force was considered as zero.

If Jacobian transpose is applied to the stair walking assist force calculated in the above manner, the stair walking assist torque can be obtained. And the stair walking assistance torque obtained in this way is applied to the rotary actuator provided in each joint, as shown in FIG. 2 .

The effect of raising the support leg of the robot occurs by the applied stair walking assistance torque. Therefore, the wearer can climb stairs with much less force than when the stair walking assist torque is not applied.

Referring to Figure 1, before the auxiliary torque application step (S300) and the repulsive force torque application step (S400), there are a step (S100) and a comparison step (S200) of determining whether one foot is supported or not. This is a step for determining whether the wearer is currently going up or down the stairs in the stair walking control method of the wearable robot.

First, it will be assumed that the wearer goes up the stairs. The state in which the robot is supported on one foot is a state that can occur both when going up or down stairs. Therefore, in the case of one-foot support, an additional step is required to determine whether the current state is a state of going up or down the stairs. Therefore, in the present invention, a comparison step (S200) is provided.

As can be seen from Figure 2, in the case of going up the stairs, the foot height of the support leg is always higher than the foot height of the swing leg in the one-leg support state. For that reason, in the comparison step (S200), when the foot height of the support leg and the swing leg is compared and the control unit determines that the foot height of the support leg is higher than the foot height of the swing leg, it is determined that the wearer is going up the stairs, and the auxiliary torque is applied step (S300) will be passed.

The situation in which the wearer goes down the stairs can be easily distinguished by using the step (S100) of determining whether to support one foot and support both feet in advance. When the wearer walks on the stairs, there are only two cases, one going up the stairs and one going down the stairs. Therefore, it is safe to regard a situation other than the situation of going up the stairs as a situation of going down the stairs.

For that reason, if it is determined that one foot is supported in the step (S100) of determining whether one foot is supported and supported by both feet, the wearer is recognized as a situation in which the wearer goes up the stairs through the comparison step (S200), and in the case of supporting both feet, the situation is going up the stairs Since this cannot be applied, the controller naturally recognizes a situation in which the user is descending the stairs and, in response, goes through a reaction force torque application step (S400).

Of course, it corresponds to one foot support, but in the comparison step (S200), a case may occur in which the foot height of the support leg is lower than the foot height of the swing leg. And this would correspond to the state on the way down the stairs. However, in the state in which the wearer is going down the stairs, there is no need for any robot control operation.

This is because, since gravity acts on the earth, no special force is required when going down the stairs, unlike going up the stairs. Therefore, there is no need to operate the robot, so it has no effect on the operation of the robot. That is, there is no need to calculate the torque value according to the movement of the wearer in the controller 500 and apply it to the actuator of the robot joint.

Therefore, in the case of going down the stairs, reducing the impact that occurs when the swing leg touches the ground and supports both feet will be the most important factor in the stair walking control method of the wearable robot. And, the stair walking control method of the wearable robot taking this into account, as shown in FIG. 1, when the swing leg touches the ground and both feet are supported while the robot is supported on one foot, the repulsion torque is applied to the swing leg by applying the ground repulsion torque value. Step (S400); is applied in a manner to perform.

If you wear a robot and go down stairs, you will have more impact on your legs than if you didn't. This is because the amount of impact the leg receives from the ground when going down the stairs is related to the weight value of the wearer. Therefore, the heavier the person's weight, the greater the amount of shock received from the ground.

In order to reduce the amount of impact received from the ground, it is necessary to provide impact compensation control to the robot. In the present invention, for this purpose, the ground reaction force is controlled by applying the torque to the joint actuator of the swing leg.

The ground repulsion torque is calculated by multiplying the difference value between the sum of the repulsion forces of the support leg and the swing leg and the weight of the robot and the person by the control constant, and is derived by substituting the ground repulsion force into the Jacobian transposition matrix.

This can be expressed as a simple formula as follows.

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: 제어상수,

:지면 반발력

,

: control constant,

: ground reaction force

: 지면 반발력 토크,

: 지지다리 지면 반발력

: ground reaction force torque,

: Support leg ground reaction force

: 스윙다리 지면 반발력, M: 로봇질량, m: 사람질량, g: 중력가속도

: Swing leg ground repulsion force, M: robot mass, m: human mass, g: gravitational acceleration

In the above formula, the value of the ground repulsion force of the support leg and the swing leg may be derived in various ways. The repulsive force value may be derived directly by attaching a load cell sensor to the robot foot, or the repulsive force value may be obtained by using the weight of a person and the robot in the control unit.

The ground repulsion torque derived by the above formula is applied to the rotary actuator of each joint of the robot by the repulsion torque application step (S400) of FIG. 1 . As an example in FIG. 3 , a case in which the calculated repulsive torque is applied to a rotary actuator located at the hip, knee, and ankle is shown.

As can be seen in FIG. 3 due to the application of the repulsion torque, the impact generated between the swing leg and the ground is reduced. Therefore, when going down the stairs while wearing a robot, there was a lot of impact on the joints of the knee and ankle due to the weight of the robot and the person before, but according to the present invention, as seen above, appropriate compensation control is made to reduce these impacts. The impact on the legs is significantly reduced.

4, the support legs 400 and the swing legs 600; And when the foot height of the support leg 400 is higher than the foot height of the swing leg 600, the step walking assistance torque value is applied to the support leg 400, and the swing leg 600 is placed on the ground in a state where the robot supports one foot. In the case of contact and support for both feet, the control unit 500 for applying the ground repulsion torque value to the swing leg 600 shows a system including a.

As mentioned above, the present invention determines whether the robot goes up or down the stairs through the step (S100) and the comparison step (S200) of determining whether the control unit 500 supports one foot and both feet as mentioned above, If it is determined that it rises, the control unit 500 reduces the load felt by the wearer through the auxiliary torque application step (S300). Similarly, when the controller 500 determines that the current robot movement is going down the stairs, it reduces the shock the wearer receives when walking the stairs through the repulsive torque application step (S400).

The control unit 500 of the stair walking control system of the wearable robot according to the present invention applies a repulsion torque applying step of applying a ground repulsion torque value to the swing leg when the swing leg touches the ground and supports both feet while the robot is supported on one foot. ; and a detailed description thereof is the same as described above.

In addition, the ground repulsion torque derived from the control unit 500 of the stair walking control system of the present wearable robot is multiplied by the control constant by the difference between the sum of the repulsion forces of the support leg and the swing leg and the weight of the robot and the person to obtain the ground repulsion force. , and is derived by substituting the ground reaction force into the Jacobian transposition matrix.

In addition, according to the stair walking control system of this wearable robot, the height of the support leg and the swing leg is calculated by the controller 500 using the angle value and the regular kinematics formed by each joint of the robot, and the stair walking assistance torque value is also supported. By substituting the foot height of the leg and the swing leg into the following equation, it can be derived from the controller 500 .

,

,

,

,

,

,

: 제어상수,

: 계단 보행 보조 힘, 계단 보행 보조 토크, J: 자코비안 행렬,

: 지지다리의 x축좌표, 스윙다리의 x축좌표, 지지다리의 발높이, 스윙다리의 발높이

: control constant,

: Stair walking aid force, Stair walking aid torque, J: Jacobian matrix,

: The x-axis coordinate of the support leg, the x-axis coordinate of the swing leg, the foot height of the support leg, the foot height of the swing leg

Although the present invention has been shown and described with reference to specific embodiments, it is within the art that the present invention can be variously improved and changed without departing from the spirit of the present invention provided by the following claims. It will be obvious to one of ordinary skill.

S100: Step of determining whether one foot is supported and whether both feet are supported
S200: comparison step S300: auxiliary torque application step
S400: Repulsion torque application step 400: Support leg
500: control unit 600: swing leg

Claims (10)

a comparison step of comparing the height of the support leg and the swing leg when the robot supports one leg;
When the foot height of the support leg is higher than the foot height of the swing leg, an auxiliary torque application step of applying a stair walking auxiliary torque value to the support leg; and
When the robot is supported with one foot and the swing leg touches the ground to support both feet, a repulsion torque application step of applying the ground repulsion torque value to the swing leg is performed;
The ground repulsion torque is calculated by multiplying the difference value between the sum of the repulsion forces of the support and swing legs and the weight of the robot and the person by the control constant, and the ground repulsion force is derived by substituting the ground repulsion force into the Jacobian transposition matrix. A method for controlling stair walking of a wearable robot. delete delete The method according to claim 1,
Step walking control method of a wearable robot, characterized in that the foot height of the support leg and the swing leg is calculated using the angle value and the regular kinematics formed by each joint of the robot. The method according to claim 1,
Stair walking assistance torque value is a step walking control method of a wearable robot, characterized in that derived by substituting the foot height of the support leg and the swing leg into the following equation.

,

,

,

: control constant,

: Stair walking aid force, Stair walking aid torque, J: Jacobian matrix,

: The x-axis coordinate of the support leg, the x-axis coordinate of the swing leg, the foot height of the support leg, the foot height of the swing leg support legs and swing legs; and
When the foot height of the support leg is higher than the foot height of the swing leg, the stair walking assistance torque value is applied to the support leg. a control unit for applying a value; including,
The control unit applies the ground repulsion torque value to the swing leg when the swing leg touches the ground and supports both feet while the robot is supported on one foot. A stair walking control system for a wearable robot, characterized in that the difference between the sums is multiplied by a control constant to calculate the ground repulsion, and derive the ground repulsion by substituting the Jacobian transposition matrix. delete delete 7. The method of claim 6,
The foot height of the support leg and the swing leg is a stair walking control system for a wearable robot, characterized in that it is calculated using the angle value and the static kinematics formed by each joint of the robot. 7. The method of claim 6,
Stair walking assistance torque value is a stair walking control system for a wearable robot, characterized in that it is derived by substituting the foot height of the support leg and the swing leg into the following equation.

,

,

,

: control constant,

: Stair walking aid force, Stair walking aid torque, J: Jacobian matrix,

: The x-axis coordinate of the support leg, the x-axis coordinate of the swing leg, the foot height of the support leg, the foot height of the swing leg

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