KR20160106959A - decoupling multi axis force sensor and wireless wearing ground reaction force measuring system - Google Patents

Abstract

The present invention relates to a separated multi-axis force sensor and a wireless wearing ground reaction force measuring system having the same and, more specifically, to a separated multi-axis force sensor which measures the power of force measuring modules, respectively, by physically separating the force measuring modules and wirelessly transfers the measured force to a management terminal, and a wireless wearing ground reaction force measuring system having the same. Therefore, the multi-axis force sensor using photo sensor-based force sensor modules prevents interference with each axis, enables the easy and cost-efficient manufacture thereof, and can be attached to a wearable system having the multi-axis force sensor modules and the sole of a robot to identify a walking cycle.

Description

[0001] The present invention relates to a wireless multi-axis force sensor and a multi-axis force sensor,

Field of the Invention [0001] The present invention relates to a wireless wearing type surface reaction force measuring system to which a multi-axis force sensor and a multi-axis force sensor are physically separated, and more particularly, And more particularly, to a wireless wearing type ground reaction force measuring system to which a physically separate multi-axis force sensor and a multi-axis force sensor are applied.

Multi-axis force sensors are commonly used to perform movements in response to human intentions when collaborating with robots, and are widely used for robot-based assembly and movement based on force control in various tasks.

As motion becomes more sophisticated, there is a growing need for a multi-axis force sensor for control and stability. In medical robots, multiaxial force sensors are applied to feed back the force of the tool used for microinvasive surgery. In humanoid robots, multiaxial force sensors are applied on the ankles or soles to control the balance of the robots. Sensors are used in the palm area to ensure stable contact with objects.

In the field of wearable robots, the ground reaction force sensor applied to the leg support device is used to provide an assist force by grasping the walking cycle. In the biomechanics field, a fixed force plate is generally used for analyzing the walking, Research on wearable floor reaction force measurement system for various motion analysis is actively being carried out.

In the case of the proposed multiaxial force sensor system, three methods are used to design an elastic body that is deformed according to the magnitude of external force externally applied.

1) In the series stacking type, uniaxial elastic bodies are arranged in series so that only independent displacement is generated for each force.

2) The parallel manipulator type is a method of replacing the joint part of a parallel type manipulator having 3 degrees of freedom or 6 degrees of freedom with a flexure joint so that the displacement of the corresponding degree of freedom is generated according to the applied force.

3) The integral type is a method of designing the shape of a slit or a spiral so that the structure of the elastic body can be generated as independent as possible for each force and calibrating it.

The characteristics of the sensor for the structure are summarized in Table 1 below. Table 1 shows the classification of the multiaxial force sensor according to the structure of the elastic body.

Stacked type [1]
(stack type) Parallel mechanism type [2]
(parallel manipulator type) Integrated [3-4]
(monolithic type)





shape

[3]

[4]
Elastomeric
size
greatness
greatness
littleness
Inter-axis interference
Low
usually greatness
(The structure becomes complicated to make it smaller)
Linearity

good
good
usually
Processability

usually
Fall
Fall
Sensitivity design

ease
ease
difficulty
Sensor calibration

ease
ease
difficulty

There are a resistance method (Force Sensing Resistor), a pressure measuring method, a strain gage method, and the like according to a method of measuring the amount of deformation of each elastic body shape. Table 2 summarizes the existing methods according to performance.

division

Resistance method
Strain gauge
system
Pressure measurement
system
Electrostatic method
Thickness and Size

Thin
The size of the structure
decision
On tube diameter
Depend on
Thin
Need voltage amplifier
not needed
need
not needed
not needed
Reaction time
Slow
speed
Slow
speed
accuracy Big
Fall
Within 3%
Fall
Within 5% Over time
Repeatability 40%
/time
-
-
-
durability
Vulnerable
good
Possible leakage
good

The resistance method is flexible as a thin film type and can be designed as small size but it is used as a switch for acquiring information about activation / deactivation degree rather than size information because the capacity is small, durability is low, and reaction time is slow.

The pressure sensor is linear within the measurement range of the sensor, and the error rate does not largely change according to the measuring range. However, the response time is regulated according to the position of the loaded force and the pressure can be converted into force. However, There is a limit to obtaining the above.

The most widely used strain gauge sensor for accurate ground reaction force measurement is sensitive to noise and has a low output voltage, so it has a disadvantage of using an additional voltage amplifier. In order to make the force sensor wireless, the output voltage of the force sensor should be more than the resolution of the ADC (analog to digital converter) used in the embedded system.

In the conventional sensor system, the ground reaction force is directly transmitted to the sensing unit (strain gauge, force sensing resistor, etc.), and when the load is repeatedly applied, the output characteristic is greatly reduced. There was no problem.

KR 10-1169940 B1

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a semiconductor device which minimizes interference between respective axial directions and uses a minimum sensor signal to facilitate fabrication and calibration, And a multi-axis force sensor that is separated from the multi-axis force sensor.

In addition, a force sensor structure with a low sensor height, which can be used as a surface reaction force measuring system or the like using an optical sensor provided as a commercial product, and a physically separated multi-axis force sensor and a multi- And an object of the present invention is to provide a wireless wearing type ground reaction force measuring system.

In addition, the multi-axis force sensor structure using the short axis force sensor which can be easily processed by the signal processing and the miniaturization, and the physically separated multi axis force sensor capable of measuring the force by the structure and the wireless wearing type ground reaction force measurement System.

According to an aspect of the present invention, there is provided a multiaxial force sensor comprising: a vertical module, which is vertically deformed by applying a vertical component force by a force applied to a point of action; And a horizontal direction module which is deformed in a horizontal direction by applying a component force are physically separated from each other and a plurality of elastic members which are respectively disposed at positions capable of measuring displacements of the elastic members in the respective axial directions, And an embedded system for measuring an output voltage with respect to each axial displacement of the elastic body measured by the displacement measurement sensor and the displacement measurement sensor and transmitting the measured output voltage to the management terminal wirelessly.

According to another aspect of the present invention, there is provided a wireless wearing type floor reaction force measuring system including a vertical direction module generating vertical displacement by a vertical direction component, Wherein the horizontal direction module, which is transmitted from the module and generates a horizontal displacement by applying a horizontal directional component, is disposed at a position where the elastic member is physically separated and the displacement of each elastic member in each axial direction is measured, A multi-axis sensor module including a sensor for displacement measurement measured for each axis direction and an embedded system for measuring an output voltage with respect to each axial displacement of the elastic body measured by the displacement measurement sensor and transmitting the measured output voltage to the management terminal wirelessly Attached to or inserted into a shoe, and attached to or inserted into the shoe during walking of a pedestrian wearing the shoe The continuous ground reaction force is measured by the multi-axis sensor module.

According to the present invention, the multiaxial force sensor structure using the optical sensor based short axis force sensor module has no interference with each axis direction, is easy to manufacture and calibrate, and can be manufactured at a low cost.

In addition, the characteristic deviation of the sensor manufactured by applying the commercial optical sensor is small, and the force in each axis direction can be easily calculated by using the output voltage.

로부터 센서의 측정용량에 따라 선정이 가능하여 기존의 반복적인 설계 변수 변경에 의한 시뮬레이션을 통해 설계하는 방법에 비교해 볼 때 설계가 간편하며 해당 판 스프링은 가공 및 구입이 용이한 효과가 있다.Further, the thickness and length of the leaf spring used in the horizontal direction are expressed by Equation

It can be selected according to the measurement capacity of the sensor, so that it is easy to design compared with the conventional method of designing through simulations by changing the design variables repeatedly, and the plate spring can be easily processed and purchased.

1 is a conceptual view of a load separation mechanism according to an embodiment of the present invention;
2 is a view showing a deformation amount due to a vertical direction component force;
3 is a view showing a deformation amount due to a horizontal directional force.
4 is a schematic view of a reflection type optical sensor and a typical distance-voltage characteristic curve of a reflection type optical sensor;
5 shows a structure of a vertical direction module.
6 is a view showing an example in which a vertical direction module and a horizontal direction module are combined;
7 is a diagram illustrating a two-axis sensor module;
8 is a view showing a configuration of an embedded system applied to a ground reaction force measuring system.
9 is a view showing an example in which a two-axis sensor module and an embedded system are attached to shoes and utilized as a wearable floor reaction force measuring system.
10 is a view illustrating a case where a wearable ground reaction force measuring system of FIG. 9 is worn by a pedestrian;
Figure 11 compares the output voltage changes of a sensor of the present invention with a commercial sensor when loading only the vertical force and only the horizontal force with the test bed for vertical / horizontal calibration;
Figure 12 compares the output voltage characteristics of the test bed and initial and after 30 minutes for the repeatability experiment.
13 is a diagram showing an example of an experimental setting for force plate verification;
Fig. 14 is a view showing the force plate measured when the user walks and wraps the force plate, and the vertical and horizontal force measuring force of the system of the present invention. Fig.
15 is a view showing a result of pressure center measurement.
16 is a view showing a sensor system coordinate system for pressure center calculation;
Figure 17 is a diagram illustrating a butterfly diagram that can be verified through the system of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

FIG. 1 is a conceptual view of a load separating mechanism according to an embodiment of the present invention, FIG. 2 is a diagram showing an amount of deformation by a vertical direction component force, and FIG. 3 is a diagram showing deformation amount by a horizontal direction component force.

As shown, the multi-axis forceps of the present invention includes vertically and horizontally oriented modules (10, 20, 30) physically separated by external forces and vertical and horizontal modules (10, 20, 30 And a voltage output from each of the reflection type optical sensors 40, 50 and 60 to a management terminal (smart phone, computer or the like). The reflection type optical sensors 40, 50, And an embedded system (not shown) for wireless transmission.

The vertical and horizontal modules 10, 20 and 30 are physically separated by a decoupling ball 70 to minimize interference in each axial direction. A decoupling ball 70 for preventing the horizontal component from being missed is disposed at the bottom of the vertical and horizontal modules 10, 20 and 30 so that deformation can occur without loss of force in the horizontal direction . The vertically and horizontally oriented modules 10, 20, 30 thus separated are assembled to form one multi-axial force welded joint. In the present invention, the decoupling ball 70 is illustrated only for the purpose of causing deformation without loss of force in the horizontal direction. However, this is only an example, A linear guide or the like may be utilized, and it is of course possible to use the cross roller guide as a guide.

The reflective optical sensors 40, 50 and 60 are arranged in the respective axial directions of the vertical and horizontal modules 10, 20 and 30, respectively, so that the vertical and horizontal modules 10, 20, 30) to obtain the output voltage of the TTL level (0 to 5 [V] level). Here, the output voltage of the reflective optical sensors 40, 50 and 60 varies depending on the distance between the reflection plate and the light receiving unit, which varies depending on the deformation of the vertical and horizontal modules 10, 20 and 30.

In particular, the displacement of the horizontal module 20, in which the horizontal directional force is applied to the horizontal direction module 20, is calculated by the following equation (1).

The load separation mechanism shown in Fig. 1 is a method for physically separating a module so that the force applied to the point of action is given an independent load by the component along each axial direction, (z-axis module) 10 and transmitted to the horizontal module (y-axis module, x-axis module) 20,30. The horizontal component force is applied in the y direction (or the x direction) and the component force is divided into the x direction again from the y direction as above.

That is, in the present invention, the forces applied to the three axes are independently calculated by the signals of the respective reflection type optical sensors. A reaction force measuring device to which one or more of such multi-axis force sensors are applied and a sensor system applied to the robot will be described below.

Hereinafter, a ground reaction force measuring system to which the multi-axis force sensor of the present invention described above is applied will be described.

4 is a schematic view of a reflection type optical sensor and a general distance-voltage characteristic curve of a reflection type optical sensor, FIG. 5 is a diagram showing a structure of a vertical direction module, and FIG. 6 is a diagram showing a vertical direction module and a horizontal direction module FIG. 7 is a diagram illustrating a two-axis sensor module, FIG. 8 is a diagram illustrating a configuration of an embedded system applied to a ground reaction force measuring system, FIG. 9 is a diagram illustrating an example of a two- FIG. 10 is a view showing an example in which a wearable floor reaction force measuring system of FIG. 9 is worn by a pedestrian, FIG. 11 is a view showing an example of a vertical / The test bed for horizontal calibration and the output voltage change of the sensor of the present invention and the commercial sensor when only the vertical direction force is applied and only the horizontal direction force is applied, Fig. 12 is a diagram showing a comparison of the test voltage for the repeatability test and the initial and after 30 minutes output voltage characteristics. Fig. 13 is a diagram showing an example of an experiment setting for the force plate verification, and Fig. FIG. 15 is a view showing the pressure center measurement result, and FIG. 16 is a graph showing the measurement results of the pressure system in the sensor system coordinate system And FIG. 17 is a diagram showing a butterfly diagram that can be confirmed through the system of the present invention.

As shown in FIG. 4A, the reflection type photosensor of the multiaxial force sensor applied to the ground reaction force measuring system of the present invention includes a light emitting diode (LED) 82 and a photo transistor 83, And the output voltage varies depending on the distance of the reflection plate 81. [0050] FIG. 4 (b) shows a general distance-voltage characteristic curve of the reflection type optical sensor.

The shape of the short axis sensor module fabricated on the basis of the reflection type optical sensor of the present invention can be variously implemented. It is desirable that the shape of the vertical (z) direction module be designed as a cylinder type for effective delivery of the horizontal directional force.

The vertical (z) direction module 90 of the multiaxial force sensor applied to the ground reaction force measuring system of the present invention includes a printed circuit board (PCB) 91, a photosensor 92, an elastic body 93 Is formed into a cylindrical shape and has a thickness of 7 mm. In this case, the vertical component of the elastic body 93 is displaced in the vertical direction. As a result, the distance between the optical sensor 92 and the reflection plate is changed, and the corresponding output voltage is changed as shown in FIG. 4 (b) Lt; / RTI >

6 is a view showing an example in which a vertical (z) direction module 90 and a horizontal (x, y) direction module 100 of a multiaxial force sensor applied to the floor reaction force measuring system of the present invention are combined, A leaf spring 120 of a horizontal (x, y) directional shear 100, a vertical z-direction module 90, (200), and a flange (300) are coupled to each other.

With this structure, horizontal force components in the horizontal direction (x, y) can be measured in the horizontal direction component transmitted from the force sensor in the vertical direction (z), and deformation in the corresponding direction can be generated using the two leaf springs 120 . FIG. 7 shows an assembly of a two-axis sensor module made of aluminum.

8 shows the configuration of the embedded system applied to the ground reaction force measuring system and the state where the embedded system is worn on the shoe. (a) is a micro controller. As the output voltage of the reflective optical sensor is output at the TTL level, the microcontroller can directly measure the value without additional amplifiers. (b) is a Bluetooth module that transmits data to a smartphone or a computer in real time using the module. Here, it goes without saying that a wireless communication module capable of wireless communication with a smartphone or a computer other than the Bluetooth module can be used. (c) shows an example of an embedded system attached to the shoe 400 attached to the back of the shoe.

9, the two-axis sensor module 500 is attached to both sides of the bottom surface of the shoe, and the embedded system 400 is attached to the rear portion of the shoe, Similarly, it is used as a ground reaction force measurement system that measures ground reaction force caused by walking of a pedestrian. In other words, it can be used to measure continuous surface reaction force which is resistant to the impact generated in the collision with the ground and the moment generated in the x-axis direction.

As shown in Fig. 11, it is possible to confirm the voltage characteristic for each axial force by the uniaxial force sensor. 11, two of the single-axis commercial force sensors are attached to the vertical and horizontal stages, respectively, and then the individual forces are transmitted to the two-axis force sensor of the present invention through the movement of the stage. When a vertical force is applied to the module, only the signal of the vertical direction module and the commercial sensor signal to which the force is applied are changed. When the horizontal force is applied, only the signal of the horizontal direction module and the horizontal commercial sensor voltage have. Therefore, it is possible to perform independent calibration between the sensors as shown in the following equation (2). That is, the calibration matrix C is a diagonal matrix, and V _i ( i = 1 to 3) represents a value obtained by subtracting the initial voltage value from the output voltage of the photosensor.

As shown in FIG. 12, it is known that when the sensor is repeatedly loaded, the output voltage drops by about 20% after 20 minutes in the case of the resistance method. Repeatability is important for the ground reaction force measurement system because the load is repeatedly applied during walking.

In the present invention, for a period of about 30 seconds, a repetitive load was applied to the experiment. Experimental results As shown in the right graph of FIG. 12, it can be seen that the output voltage of the first 20 seconds and the output voltage of 1800 seconds are constant.

That is, the reflection type optical sensor of the present invention is not attached directly to the elastic body connected with the point of force but attached to the opposite side capable of measuring the displacement of the deformable body, so that the load is not applied to the reflection type optical sensor even under repeated loads Indirectly, the strain intensity is measured through the intensity of light. Therefore, it can be confirmed through experiments that the output voltage characteristic does not vary greatly with cyclic loading. In the present invention, the reflection type optical sensor has been described only for the structure that is attached to the opposite side capable of measuring the displacement of the deformable body, but this is merely one embodiment and is not necessarily arranged on the opposite side, It is of course possible to arrange it at any position where it is possible to measure the displacement of the deformable member causing the deformation.

As shown in FIGS. 13 and 14, when the ground reaction force values measured by the walkers on the pedestrian's foot are compared with each other, the accuracy between the force values measured on the force plate and the force values measured on the ground reaction force measuring system of the present invention when walking on the fixed- The experiment as shown in FIG. 13 was performed. In order to confirm the pressure center value, a marker is attached to the edge of the force plate and the foot of the wearable system, the ankle center, and the shin portion, and the force measured at each marker position and the force plate and the force value measured by the ground reaction force measuring system of the present invention Respectively. Measurement results As shown in FIG. 14, vertical and horizontal measurement forces of a force plate (dotted line) and a ground reaction force measurement system of the present invention (solid line) measured when waving on the force plate and waving the body were measured similarly.

15 to 17, the pressure center of the surface reaction force measuring system of the present invention is calculated as follows. The origin (600) is defined at the center of the two sensors (500), the distance from the center to one sensor is denoted by l, and the height of the sensor is denoted by h.

FIG. 15 is a result obtained by calculating the calculated values and the measured values while moving back and forth on the force plate according to the coordinate system of the system of the present invention. In Fig. 15, the red line represents the pressure center measured through the force plate and the optical marker, and the blue line represents the pressure center measured through the surface reaction force measuring system of the present invention.

The ground reaction force measuring system according to the present invention can differentiate the system from the system that measures only the vertical direction force or the pressure only through the short axis ground reaction force and outputs the vector form output through the horizontal direction and vertical direction force and pressure center measured during walking , Which can be used primarily in systems for gait analysis or walking aids. This vector image, measured during a normal gait, is called a butterfly diagram because it is similar to a butterfly shape. As shown in FIG. 17, a known butterfly diagram can be obtained by using a measurement value obtained by a surface reaction force measuring system equipped with the two-axis force sensor module of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

10: vertical direction module
20, 30: Horizontal direction module
40,50,60: Reflective optical sensor
70: separating ball

Claims (7)

As a multi-axial force sensor,
A vertical module in which a vertical direction component due to a force applied to a point of action is applied and deformed in a vertical direction, and a horizontal direction module which is transmitted from the vertical direction module and applied with a horizontal direction component and deforms in a horizontal direction;
A displacement measuring sensor disposed at a position capable of measuring displacement of each of the axial directions of the elastic body and measuring the displacement of the elastic body in each axial direction; And
An embedded system for measuring an output voltage with respect to a displacement of each of the axial directions of the elastic body measured by the displacement measuring sensor and wirelessly transmitting the measured output voltage to a management terminal;
/ RTI >
The method according to claim 1,
In order to minimize interference in each axial direction, the elastic body is provided with separating means in the vertical direction module and the horizontal direction module, respectively, so that the vertical direction module and the horizontal direction module are physically separated
Wherein the multi-axis force sensor comprises:
The method of claim 2,
The horizontal directional component is applied to the horizontal direction module without loss by the separating means disposed in the vertical direction module and the horizontal direction module,
Wherein the multi-axis force sensor comprises:
A wireless wearable floor reaction force measuring system to which a multi-axis force sensor is applied,
A vertical direction module in which a vertical displacement is generated by a vertical direction component and a horizontal direction module in which a horizontal direction component is generated by a horizontal direction component transmitted from the vertical direction module, A sensor for measuring a displacement, which is disposed at a position capable of measuring axial displacement, for each axial direction of the elastic body, and a sensor for measuring a displacement of the elastic body measured by the displacement measuring sensor, Wherein the multi-axis sensor module includes a multi-axis sensor module attached to or inserted into the shoe, and a multi-axis sensor module attached or inserted into the shoe when the pedestrian wearing the shoe is walking, The reaction force is measured
A wireless wearing type ground reaction force measuring system with multi - axis force sensor.
The method of claim 4,
The multi-axial sensor module is attached or inserted to at least one of a front portion and a rear portion of the shoe bottom surface, and a continuous floor reaction force due to the walking of the pedestrian is measured
Wherein the multi-axial force sensor is applied to the ground surface reaction force measuring system.
The method of claim 4,
The displacement measurement sensor is a reflection type optical sensor in which a light emitting diode and a phototransistor are combined, and an output voltage of 0 to 5 [V] level is generated for each displacement in the axial direction of the elastic body
Wherein the multi-axial force sensor is applied to the ground surface reaction force measuring system.
The method of claim 6,
The embedded system includes:
A microcontroller for measuring an output voltage at a level of 0 to 5 [V] with respect to a displacement of each of the axial directions of the elastic body measured by the displacement measuring sensor; And
And a wireless communication module for wirelessly transmitting, to the management terminal, an output voltage of 0 to 5 [V] level with respect to displacement of the elastic body measured by the microcontroller in each axial direction
Wherein the multi-axial force sensor is applied to the ground surface reaction force measuring system.

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