WO2008105590A1

WO2008105590A1 - Stiffness sensor and muscle activity sensor having the same

Info

Publication number: WO2008105590A1
Application number: PCT/KR2008/000831
Authority: WO
Inventors: Hwa Cho Yi; Seok Hwan Kim; Moromugi Shunji; Ishimatsu Takakazu
Original assignee: Industry-Academic Cooperation Foundation, Yeungnam University
Priority date: 2007-02-27
Filing date: 2008-02-13
Publication date: 2008-09-04
Also published as: KR20080079397A; KR100867078B1

Abstract

Disclosed herein is a hardness sensor. The hardness sensor includes a button, an upper plate, a lower plate, a buffering member, a first pressure sensor, and a second pressure sensor. The button is configured to come into contact with a test target. The upper plate is configured such that one surface thereof is coupled with the button so as to enable pressure to be transmitted therebetween. The lower plate is coupled with the remaining surface of the upper plate so as to enable the pressure to be transmitted therebetween. The buffering member is provided between the upper and lower plates to be elastically deformable and to buffer the pressure between the upper and lower plates. The first pressure sensor measures the pressure that is applied between the button and the upper plate. The second pressure sensor measures pressure, which is buffered and is applied between upper and lower plates.

Description

STIFFNESS SENSOR AND MUSCLE ACTIVITY SENSOR

HAVING THE SAME

Technical Field

[1] The present invention relates to a hardness sensor and a muscle activity sensor using the same. More particularly, the present invention relates to a hardness sensor, which can easily measure the hardness of a test target using a buffering member and two pressure sensors regardless of the amount of pressure that is applied, and to a muscle activity sensor, which enables the hardness of muscle to be measured using the hardness sensor and, at the same time, enables electromyogram signals to be measured at a single position on a human body using a myoelectric sensor, thus accurately measuring the activity of muscle. Background Art

[2] Recently, with the development of the computer and control technology, research has been actively conducted in order to use various devices which require control, such as medical equipment, sports equipment, game devices and robot control input devices, as components of control systems, to applications pertaining to humans and to enable the devices to be more stably and reliably operated. In order to realize such a system, Human-Computer Interface (HCI) technology, which enables the conversion and the transmission and reception of information between humans and machines, is required, and thus various HCI technologies have been developed.

[3] As devices based on the most general HCI technology, there are keyboards, mice and the like. These devices are not suitable for disabled persons or the elderly because it is not easy for them to manipulate the devices. For this reason, user-based HCI technology, which uses video or audio, has recently been developed in consideration of convenience for users. However, there are problems in that user-based HCI technology using video is expensive because the amount of data to be processed is large, and in that user-based HCI technology using audio is influenced by surrounding noise and the environment.

[4] Accordingly, recently, new HCI technology using biological signals has been developed. The HCI technology using biological signals is based on a method of measuring the activity of muscle and controlling a specific device according to the measured activity of muscle, and is currently widely used.

[5] A typical muscle activity sensor, which can measure the activity of muscle, chiefly employs a myoelectric sensor, which can detect Electromyogram (EMG) signals. The muscle activity sensor measures the activity of muscle when the myoelectric sensor is attached to a portion of the arms or legs of a human body and detects EGM signals which are generated in a manner that varies with the degree of contraction of the muscle. In this case, the EGM signals are electrical signals that are generated along the muscle fiber from the surface of muscle according to motion of the human body, and are widely used for HCI technology because they are more easily detected than other biological signals, such as Electroencephalogram (EEG) signals or electrooculogram (EOG) signals.

[6] However, the above-described myoelectric sensor is problematic in that error attributable to noise is easily generated because the generated electrical signals are weak and it is thus very sensitive to various kinds of noise, and in that a separate amplifying device for amplifying the weak electrical signals is required for actual application to a device. Furthermore, the above-described myoelectric sensor is problematic in that it is difficult to acquire the same signal values under the same conditions, in particular, because the generation of EGM signals is lowered when exercise is conducted for a long time due to the characteristics of the human body, and in that the electrical signal values are affected greatly by the state of the skin because the electrical signals are detected through the skin. Accordingly, the muscle activity sensor using a myoelectric sensor cannot accurately measure the activity of muscle due to the problems with the myoelectric sensor.

[7] Meanwhile, in order to mitigate the problems with the above-described myoelectric sensor, which are caused when measuring the activity of muscle, attempts to measure the activity of muscle based on a method of measuring the hardness of muscle have recently been made. However, a typical hardness sensor is problematic in that it is structurally difficult to accurately measure the hardness of soft material, and in that it is not suitable for mounting to some positions on the human body. Disclosure of Invention Technical Problem

[8] Accordingly, the present invention has been invented to solve the above-described problems, and an object of the present invention is to provide a hardness sensor, which can easily measure the hardness of a test target using a buffering member and two pressure sensors regardless of the amount of pressure that is applied, and is also to provide a muscle activity sensor, which enables the hardness of muscle to be measured using the hardness sensor and, at the same time, enables EGM signals to be measured at a single position on a human body using a myoelectric sensor, thus accurately measuring the activity of muscle. Technical Solution

[9] In order to accomplish the above object, the present invention provides a hardness sensor, including: a button configured to come into contact with a test target; an upper plate configured such that one surface thereof is coupled with the button so as to enable pressure to be transmitted therebetween; a lower plate coupled with the remaining surface of the upper plate so as to enable the pressure to be transmitted therebetween; a buffering member provided between the upper and lower plates to be elastically deformable and to buffer the pressure between the upper and lower plates; a first pressure sensor for measuring the pressure that is applied between the button and the upper plate; and a second pressure sensor for measuring the pressure, which is buffered and is applied between upper and lower plates; wherein the hardness of the test target is measured using the ratio of pressures measured by the first and second pressure sensors.

[10] In addition, the present invention provides a muscle activity sensor, including: the hardness sensor; and a myoelectric sensor attached to an end of a button and configured to detect EGM signals; wherein the hardness of muscle, which is detected by the hardness sensor, and EGM signals, which are detected by the myoelectric sensor, are simultaneously measured at an identical point to measure the activity of muscle.

Advantageous Effects

[11] As described above, in the present invention, EGM signals and the hardness of muscle are simultaneously measured from the same position on a human body using both the myoelectric sensor, which can detect EGM signals, and the hardness sensor, which can measure the hardness of muscle, so that the activity of muscle can be accurately measured. [12] Furthermore, in the present invention, the buffering member and the two pressure sensors are used, and thus the hardness of a test target can be easily measured regardless of the amount of pressure that is applied.

Brief Description of the Drawings [13] FIG. 1 is a schematic exploded perspective view showing a hardness sensor according to an embodiment of the present invention; [14] FIG. 2 is schematic sectional views showing the assembly structure of a second pressure sensor according to an embodiment of the present invention; [15] FIG. 3 is a schematic exploded perspective view showing a muscle activity sensor according to an embodiment of the present invention; and [16] FIG. 4 is a longitudinal sectional view of the muscle activity sensor of FIG. 3.

Mode for the Invention [17] A preferred embodiment of the present invention is described in detail with reference to the accompanying drawings. First, it should be noted that, when reference numerals are used to indicate the components of each drawing, the same reference numerals are used throughout the different drawings to designate the same or similar components. In the description of the present invention, when it is determined that detailed descriptions of well-known constructions or functions may be unnecessary and may make the gist of the present invention unclear, the detailed descriptions will be omitted.

[18] FIG. 1 is a schematic exploded perspective view showing a hardness sensor according to an embodiment of the present invention, and FIG. 2 is schematic sectional views showing the assembly structure of a second pressure sensor according to an embodiment.

[19] The hardness sensor according to the embodiment of the present invention includes a button 10, which is configured to come into contact with the surface of a test target, the hardness of which will be measured, upper and lower plates 20 and 30, a buffering member 40, which is elastically deformable, and first and second pressure sensors 50 and 60.

[20] The button 10 is configured such that one end thereof comes into contact with the surface of the test target, and the other end thereof is coupled to one surface of the upper plate 20. In this case, the button 10 and the upper plate 20 are coupled such that pressure can be mutually transmitted therebetween. The first pressure sensor 50 is inserted between the button 10 and the upper plate 20 to measure the pressure that is applied between the button 10 and the upper plate 20. The buffering member 40, which is elastically deformed by pressure, is provided between the upper and lower plates 20 and 30. The upper and lower plates 20 and 30 are coupled to each other by the buffering member 40, which is interposed therebetween so that the pressure that is applied between the upper and lower plates 20 and 30 can be mutually transmitted to the upper and lower plates 20 and 30 via the buffering member 40. In this case, the buffering member 40 is made of elastically deformable material, and functions to buffer the pressure that is applied between the upper and lower plates 20 and 30. Furthermore, the second pressure sensor 60 is provided at a predetermined location between the upper and lower plates 20 and 30 to measure the pressure that is applied between the upper and lower plates 20 and 30. In this case, the pressure that is applied between the upper and lower plates 20 and 30, which is measured by the second pressure sensor 60, corresponds to the pressure that is applied therebetween after being buffered by the buffering member 40.

[21] The hardness sensor according to the present invention, having the above-described structure, enables the hardness of the test target to be measured using a ratio of the pressures that are measured by the first and second pressure sensors 50 and 60. The hardness sensor according to the present invention may be very usefully used to measure the hardness of soft material, such as rubber or silicon, rather than to measure the hardness of hard material, such as metal, and is very suitable for measuring the hardness of muscle at a predetermined position on a human body.

[22] A typical hardness measuring device for measuring the hardness of soft material is based on a method of using a spring gauge, and measures the hardness of the test target in such a way as to bring a probe into contact with the surface of the test target, press the surface at a predetermined pressure, and measure the amount of compression of the spring of the spring gauge. In the above-described method, when the hardness of the test target varies according to time and environmental conditions, whether the applied pressure varies or the hardness of the test target varies cannot be determined. For this reason, in a typical hardness measurement device, control is performed such that the pressure applied to the probe over the test target can be maintained constant, or a separate control device or pressure measurement device is provided to measure the magnitude of the pressure.

[23] Unlike the typical hardness measuring device, the hardness sensor according to the present invention is configured such that the hardness of the test target can be measure using a ratio of pressures, which are measured by the first and second pressure sensors 50 and 60, without requiring that the pressure applied to the button 10, which comes into contact with the test target, be maintained constant.

[24] The principle of measuring the hardness using the hardness sensor according to the present invention is described below. In the present invention, when a pressure having a predetermined level is applied to the outer surface of the lower plate 30 in the state in which the button 10 is in contact with the surface of a test target, the pressure is transmitted to the upper plate 20 through the buffering member 40 and, subsequently, is transmitted to the button 10. In this case, the pressure that is applied to the outer surface of the lower plate 30 is buffered and is then measured by the second pressure sensor 60, and the pressure that is generated by the reaction force from the surface of the test target is measured by the first pressure sensor 50. In this case, the presses that are measured by the first and second pressure sensors 50 and 60 are mutually affected by an interaction attributable to the structure of the present invention, so that the present invention is configured to measure the hardness of the test target using the ratio of the pressures measured by the pressure sensors 50 and 60.

[25] That is, as the pressure that is applied to the outer surface of the lower plate 30 is increased, the pressure that is measured by the second pressure sensor 60 is increased. This pressure increases the pressure between the button 10 and the upper plate 20, and thus the pressure that is measured by the first pressure sensor 50 is also increased. In this case, the pressure between the upper and lower plates 20 and 30, which is measured by the second pressure sensor 60, and the pressure between the button 10 and the upper plate 20, which is measured by the first pressure sensor 50, are increased by an interaction attributable to the structure of the present invention while maintaining a ratio within a predetermined range.

[26] Accordingly, the hardness sensor according to the present invention can precisely measure the hardness using the ratio of the pressures measured by the first and second pressure sensors 50 and 60, even when the pressure that is applied to the outer surface of the lower plate 30 varies rather than remaining constant. Furthermore, the hardness may be still more precisely measured if the ratio of the pressures that are measured by the first and second pressure sensors 50 and 60 for a specific test target is charted for use thereof.

[27] Accordingly, in the hardness sensor according to the present invention, it is not necessary to maintain the applied pressure constant, so that a separate control device is not required and, in addition, the hardness can be easily measured. Furthermore, even when the upper and lower plates 20 and 30 are not maintained parallel to each other, that is, the direction of the applied pressure is not perpendicular to the outer surface of the lower plate 30, the pressure can be precisely measured because the buffering member 40 is provided between the upper and lower plates 20 and 30 to compensate for variation in the pressure using buffering.

[28] Based on the above-described structure and operation, it is preferred that the buffering member 40 according to an embodiment of the present invention be formed by charging gaseous material or semi-solid material in an elastically deformable membrane at a predetermined pressure so as to be sensitively elastically deformed by pressure. Furthermore, as shown in FIGS. 1 and 2, the buffering member 40 is formed to have a ring shape, and forms a concentric circle together with the upper and lower plates 20 and 30, and thus it is possible to dispose the buffering member 40 between the upper and lower plates 20 and 30.

[29] Meanwhile, as shown in (a) to (c) of FIG. 2, the second pressure sensor 60 may be attached to any of various predetermined positions between the upper and lower plates 20 and 30 to measure the pressure that is buffered by buffering member 40, which is located between the upper and lower plates 20 and 30, and is applied therebetween.

[30] As shown in (a) of FIG. 2, the second pressure sensor 60 may be inserted and mounted between the buffering member 40 and the lower plate 30 to measure the pressure that is transmitted between the lower plate 30 and the buffering member 40. Furthermore, the second pressure sensor 60 may be inserted between the upper plate 20 and the buffering member 40.

[31] Furthermore, as shown in (b) of FIG. 2, the second pressure sensor 60 may be inserted and located in the buffering member 40 to measure the variation of pressure in the buffering member 40 attributable to variation in the pressure that is applied to the outer surface of the lower plate 30.

[32] Furthermore, as shown in (c) of FIG. 2, in the case where the buffering member 40 is formed to have a ring shape, the respective surfaces of the buffering member 40 may be airtightly coupled to the upper and lower plates 20 and 30 so that a pressure measurement space 41 is formed in the central portion of the buffering member 40. The second pressure sensor 60 may be provided at a predetermined location in the pressure measurement space 41 to measure the variation of pressure in the pressure measurement space 41, which is caused when the interval between the upper and lower plates 20 and 30 is varied by variation in the pressure that is applied to the outer surface of the lower plate 30.

[33] Accordingly, the above-described hardness sensor is useful to measure the hardness of soft material, and can easily measure the hardness regardless of the amount of pressure that is applied. A muscle activity sensor having a structure in which the hardness sensor and a separate myoelectric sensor are coupled to each other is described below.

[34] FIG. 3 is a schematic exploded perspective view showing a muscle activity sensor according to an embodiment of the present invention, and FIG. 4 is a longitudinal sectional view of the muscle activity sensor of FIG. 3.

[35] The muscle activity sensor, shown in FIGS. 3 and 4, is a sensor that is configured such that a myoelectric sensor 70 is attached to the hardness sensor, shown in FIGS. 1 and 2, thus enabling the activity of muscle at a single position on the human body to be measured by simultaneously measuring both the hardness of muscle and EGM signals.

[36] The hardness sensor shown in FIGS. 1 and 2 is very suitable for measuring the hardness of muscle at a predetermined position on the human body, as described above. In contrast, the muscle activity sensor according to the embodiment of the present invention is configured such that the myoelectric sensor 70 for detecting EGM signals is attached to one end of the button 10 of the hardness sensor to simultaneously measure both the hardness of muscle and the EGM signals.

[37] Furthermore, as shown in FIG. 3, in addition to the myoelectric sensor 70, which is attached to one end of the button 10 of the hardness sensor, a plurality of myoelectric sensors may be attached to the upper surface of the upper plate 20.

[38] The muscle activity sensor having the above-described structure can easily measure the hardness of muscle at a predetermined position on the human body and, at the same time, can measure EGM signals at the same position, so that the activity of muscle can be precisely measured. Generally, the muscle activity sensor is attached to a predetermined position on the human body, that is, a position on the arms, legs or the like, using a band that covers the outer surface of the lower plate 30. In this case, the pressure that is applied to the outer surface of the lower plate 30 may vary according to the pressing force that is generated when the band covering the outer surface of the lower plate 30 is worn. In spite of the above-described variation in pressure, the muscle activity sensor according to the present invention can precisely measure the hardness of muscle using the operational principle of the hardness sensor as described herein. Furthermore, the muscle activity sensor can precisely measure the hardness of muscle even when the pressing force of the band varies according to the expansion and contraction of muscle in the state in which the band is worn, and thus the pressure that is applied to the outer surface of the lower plate 30 varies.

[39] The muscle activity sensor according to the present invention is a sensor that measures the EGM signals, which are generated when muscle is expanded and contracted while conducting exercise and, at the same time, measures the hardness of muscle, thus precisely measuring the activity of muscle. Accordingly, the muscle activity sensor may be applied to various devices based on HCI technology, such as medical equipment, sports equipment, and robot control input devices.

[40] The above description is illustrative in order to convey the technical spirit of the present invention, and a person having ordinary knowledge in the technical field to which the present invention pertains will appreciate that various modifications and variation are possible within the range that does not depart from the substantial characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not limitative to the spirit of the present invention and are only illustrative, and the scope of the technical spirit of the present invention is not defined by the embodiments. The scope of the present invention should be understood with reference the accompanying claims, and all technical variations within the equivalent scope should be understood as being included within the scope of the present invention.

[41]

Claims

[1] A hardness sensor, comprising: a button configured to come into contact with a test target; an upper plate configured such that one surface thereof is coupled with the button so as to enable pressure to be transmitted therebetween; a lower plate coupled with a remaining surface of the upper plate so as to enable the pressure to be transmitted therebetween; a buffering member provided between the upper and lower plates to be elastically deformable and to buffer the pressure between the upper and lower plates; a first pressure sensor for measuring the pressure that is applied between the button and the upper plate; and a second pressure sensor for measuring pressure, which is buffered and is applied between upper and lower plates; wherein a hardness of the test target is measured using a ratio of pressures measured by the first and second pressure sensors. [2] The hardness sensor according to claim 1, wherein the buffering member is formed by charging gaseous material in a membrane, which is elastically deformable, at a predetermined pressure. [3] The hardness sensor according to claim 1, wherein the buffering member is formed by charging semi-solid material in a membrane, which is elastically deformable. [4] The hardness sensor according to any one of claims 1 to 3, wherein the second pressure sensor is inserted between the upper or lower plate and the buffering member to measure the pressure that is mutually transmitted between the upper or lower plate and the buffering member. [5] The hardness sensor according to any one of claims 1 to 3, wherein the second pressure sensor is located in the buffering member to measure pressure in the buffering member. [6] The hardness sensor according to any one of claims 1 to 3, wherein the buffering member is formed to have a ring shape. [7] The hardness sensor according to claim 6, wherein: the buffering member is configured such that respective surfaces thereof are airtightly coupled with the upper and lower plates so that a pressure measurement space is formed in a central portion thereof; and the second pressure sensor is located in the pressure measurement space to measure pressure in the pressure measurement space. [8] A muscle activity sensor, comprising: the hardness sensor of claim 1 ; and a myoelectric sensor attached to an end of a button and configured to detect Elec- tromyogram (EGM) signals; wherein a hardness of muscle, which is detected by the hardness sensor, and

EGM signals, which are detected by the myoelectric sensor, are simultaneously measured at an identical point to measure an activity of muscle. [9] The muscle activity sensor according to claim 8, further comprising a plurality of myoelectric sensors that is attached to an upper surface of the upper plate.