Muscle force estimation device and muscle force estimation method

Abstract

To provide a muscle force estimation device and a muscle force estimation method capable of estimating muscle forces of individual muscle groups classified by function in a lower thigh part.SOLUTION: The muscle force estimation device causes a subject to exert end forces in four directions in a two-dimension plane, and measures the end forces exerted in the respective directions by a detection unit. The end force exerting position is estimated based on the measured end force and the moment around the z-axis orthogonal to the two-dimension plane detected by the detection unit when the end force is measured. Each measured end force is converted into a joint torque based on the estimated end force exerting position. On the basis of the converted joint torque, the output distribution of the hexagonal joint torque in which the lengths of all opposite sides are equal is plotted on a torque plane with the joint torque relating to the knee joint as one axis and the joint torque relating to the foot joint as the other axis perpendicular to the one axis. Based on the output distribution drawn by the drawing unit, the muscle group torque of each muscle group of the crus is estimated.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a muscle strength estimation device and a muscle strength estimation method for estimating muscle strength of the lower leg. [Background technology]

[0002] In recent years, human motion analysis has become increasingly important, especially in the fields of sports and rehabilitation. For example, evaluation of maximum muscle strength is required as an indicator of functional recovery and training effectiveness. However, it is difficult to directly measure muscle strength in clinical settings. Furthermore, human movements occur in three-dimensional space, and it is difficult to perform three-dimensional analysis that includes internal and external rotation of the lower limbs when estimating lower limb muscle strength.

[0003] Therefore, joint torque measurement has traditionally been used to evaluate maximum muscle strength. Joint torque measurement has the advantages of being easy and highly reproducible. However, because the measured joint torque is the resultant force of multiple muscles, it has the disadvantage of being unable to evaluate muscle strength separately for monoarticular and biarticular muscles.

[0004] On the other hand, there is a method for evaluating muscle strength using a simple 3:6 muscle model that classifies muscles acting on the hip-knee joint (thigh) by function on a two-dimensional plane based on functional effective muscle theory (e.g., Patent Documents 1 and 2). This method makes it possible to evaluate individual muscle groups by utilizing the fact that the output distribution, which indicates the maximum range of the force (tip force) exerted by each muscle group at the tip of the foot, is hexagonal.

[0005] Furthermore, Non-Patent Document 1 discloses a method for estimating the muscle strength of the entire lower limb acting on the three joints of the hip, knee, and foot by extending the functional effective muscle theory to the knee-ankle joint (lower leg) and adding a five-muscle model of the lower leg to the above-mentioned three-to-six muscle model of the thigh. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6615441 [Patent Document 2] Patent No. 6593751 [Non-patent literature]

[0007] [Non-Patent Document 1] Nishida, Isamu, and three others, "Estimation method of lower limb muscle strength considering the function of antagonistic and biarticular muscles - Estimation of lower limb muscle strength in vertical jumping -", Ergonomics, Japan Ergonomics Society, 2011, Vol. 47, No. 6, pp. 244-251 Summary of the Invention [Problem to be solved by the invention]

[0008] However, although Non-Patent Document 1 describes the estimation of muscle strength of the entire lower limb, it does not evaluate muscle strength of the lower leg. Furthermore, when evaluating muscle strength of the thigh based on the functional effective muscle theory, the position at which the distal end force exerted by the hip joint and knee joint at the tip of the foot is fixed regardless of the direction of exertion. On the other hand, when attempting to evaluate muscle strength of the lower leg based on the functional effective muscle theory, the position at which the distal end force exerted by the knee joint and ankle joint at the tip of the foot is exerted moves depending on the direction of exertion. Therefore, the techniques disclosed in Patent Documents 1 and 2 cannot be directly applied to the evaluation of muscle strength of the lower leg based on the functional effective muscle theory.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a muscle strength estimation device and a muscle strength estimation method that can estimate the muscle strength of individual muscle groups in the lower leg that are classified by function. [Means for solving the problem]

[0010] To achieve this object, a first aspect of the present invention is a muscle strength estimation device that estimates muscle strength of a subject's lower limbs by dividing it into five muscle groups classified by function as muscle groups that have an effect on movement within a two-dimensional plane that includes a knee joint, an ankle joint, and a distal end force exertion position where a distal end force is exerted by the knee joint and the ankle joint, and the muscle groups are an anterior knee group that acts on the knee joint and is a combination of mono-articular muscles and bi-articular muscles on the front side of the thigh, a posterior knee group that acts on the knee joint in antagonism to the anterior knee group and is a combination of mono-articular muscles and bi-articular muscles on the back side of the thigh, and an anterior mono-articular muscle that acts on the ankle joint. and a biarticular calf muscle group which is a posterior biarticular muscle that acts on the knee joint and the ankle joint without having an antagonist muscle. The muscle strength estimation device includes a detection unit that detects a tip force exerted by the knee joint and the ankle joint at the tip force exertion position by the knee joint and the ankle joint at least in two orthogonal axial directions within the two-dimensional plane and is capable of detecting at least a moment around an axis orthogonal to the two-dimensional plane, and a control unit, and the control unit controls the subject to apply the tip force to the subject within the two-dimensional plane. a tip force measuring unit that exerts the tip force in a plurality of directions and measures the tip force exerted in each direction by the detection unit; a tip force exertion position estimating unit that estimates the tip force exertion position based on the tip force measured by the tip force measuring unit and a moment about an axis orthogonal to the two-dimensional plane detected by the detection unit when the tip force is measured; a torque conversion unit that converts each of the tip forces measured by the tip force measuring unit into a joint torque based on the tip force exertion position estimated by the tip force exertion position estimating unit; a drawing unit that draws a hexagonal joint torque output distribution, with all opposite sides of the hexagon having equal lengths, on a torque plane having the joint torque related to the knee joint as one axis and the joint torque related to the ankle joint as another axis perpendicular to the one axis, based on the joint torque; and a muscle group torque estimating unit that estimates the muscle group torque of the biarticular muscles of the calf based on one side of the hexagon of the output distribution drawn by the drawing unit, estimates the muscle group torque of each of the anterior knee muscle groups and the posterior knee muscle groups based on another side of the hexagon, and estimates the muscle group torque of each of the anterior foot muscle groups and the posterior foot muscle groups based on the remaining side of the hexagon.Equipped with.

[0011] A second aspect of the present invention is the muscle force estimation device according to the first aspect, further comprising a fixing unit that covers and fixes the foot, and the tip force is exerted with the foot fixed to the fixing unit, and the detection unit detects the tip force while fixed to the bottom of the fixing unit. Note that the fixing unit may not only cover the entire foot, but also cover part of the foot. Furthermore, the fixing unit may be a single member that fixes the foot, or a plurality of members that fix the foot.

[0012] In a third aspect of the present invention, in the muscle strength estimation device according to the second aspect, a moment about an axial direction orthogonal to the two-dimensional plane is calculated for each position on the assumption that the distal end force measured by the distal end force measuring unit is exerted at each position of the fixing unit, and the position at which the calculated moment has a value closest to the moment about the axial direction orthogonal to the two-dimensional plane detected by the detecting unit is estimated to be the distal end force exertion position.

[0013] A fourth aspect of the present invention is the muscle strength estimation device according to the second or third aspect, wherein the fixing part is configured to be positionally adjustable at least in a direction connecting the knee joint and the ankle joint of the subject.

[0014] A fifth aspect of the present invention is a muscle strength estimation device according to any one of the first to fourth aspects, wherein the drawing unit draws the output distribution of the joint torque of the hexagon under the constraint that the maximum measurement points of the joint torque identified corresponding to each side of the hexagon are included on or inside each side of the hexagon.

[0015] A sixth aspect of the present invention is the muscle strength estimation device according to any one of the first to fifth aspects, wherein the tip force measuring unit exerts the tip force on the subject in each of the plurality of directions, at least in knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion.

[0016] In a seventh aspect of the present invention, in the muscle strength estimation device according to any one of the first to sixth aspects, the control unit includes a first monitor display control unit that causes a display unit to display a first chart indicating in real time the magnitude and direction of the distal end force detected by the detection unit, and a first guideline display control that, when the distal end force measurement unit exerts the distal end force on the subject in one direction, causes the first chart to display a guideline of the direction in which the distal end force will be exerted relative to the one direction.

[0017] In an eighth aspect of the present invention, in the muscle force estimation device according to any one of the second to fourth aspects, the control unit includes: a second monitor display control unit that causes a display unit to display a second chart showing in real time the shape of the fixing part and the distal end force exertion position estimated by the distal end force exertion position estimation unit relative to the shape; and a second guideline display control that, when the distal end force measurement unit exerts the distal end force on the subject in one direction, causes the second chart to display a guideline of the distal end force exertion position relative to the one direction.

[0018] A ninth aspect of the present invention is a muscle strength estimation device according to any one of the first to eighth aspects, wherein the control unit is provided with a joint torque display control unit that controls the display unit to display the maximum values ​​of the joint torque in each direction of knee extension, dorsiflexion, knee flexion, and plantar flexion, in the joint torque converted by the torque conversion unit.

[0019] A tenth aspect of the present invention is a muscle strength estimation method for estimating muscle strength of the lower limbs of a subject by dividing the muscle strength into five muscle groups classified by function as muscle groups that have an effect on movement in a two-dimensional plane including a knee joint, an ankle joint, and a distal end force exertion position where a distal end force is exerted by the knee joint and the ankle joint, the muscle groups being: an anterior knee group that acts on the knee joint and is a combination of mono-articular muscles and bi-articular muscles on the front side of the thigh; a posterior knee group that acts on the knee joint in opposition to the anterior knee group and is a combination of mono-articular muscles and bi-articular muscles on the back side of the thigh; and a posterior knee group that acts on the ankle joint. the anterior foot muscle group being front mono-articular muscles acting on the ankle joint in an antagonistic manner to the anterior foot muscle group; the posterior foot muscle group being rear mono-articular muscles acting on the ankle joint in an antagonistic manner to the anterior foot muscle group; and the bi-articular calf muscle group being rear bi-articular muscles acting on the knee joint and the ankle joint without having an antagonist muscle, and the muscle strength estimation method includes a tip force measuring step of making the subject exert the tip force in a plurality of directions in the two-dimensional plane and measuring the tip force exerted in each direction in at least two orthogonal axial directions in the two-dimensional plane; a torque conversion step of converting each of the tip forces measured in the tip force measurement step into a joint torque based on the tip force exertion position estimated in the tip force exertion position estimating step; a drawing step of drawing a hexagonal joint torque output distribution with all opposite sides having equal lengths on a torque plane having a joint torque related to the knee joint as one axis and a joint torque related to the ankle joint as another axis perpendicular to the one axis, based on the joint torque converted in the torque conversion step; and a muscle group torque estimating step of estimating muscle group torque of the biarticular muscles of the calf based on one side of the hexagon of the output distribution drawn in the drawing step, estimating muscle group torque of each of the anterior knee muscles and the posterior knee muscles based on another side of the hexagon, and estimating muscle group torque of each of the anterior foot muscles and the posterior foot muscles based on the remaining side of the hexagon. [Effects of the Invention]

[0020] According to the muscle strength estimation device of the first aspect of the present invention, muscle strength of the lower leg (knee-ankle joint) is estimated by dividing the muscles of the lower leg into five muscle groups classified by function. The muscle strength of each muscle group of the lower leg is estimated based on the fact that when the joint torque generated based on the distal end force acting at the distal end force exertion position is plotted on a torque plane, the output distribution of the joint torque forms a hexagon with equal lengths of opposite sides. Here, the torque plane is a plane in which one axis represents the joint torque related to the knee joint and the other axis perpendicular to the first axis represents the joint torque related to the ankle joint.

[0021] Specifically, when the subject exerts tip forces in multiple directions in a two-dimensional plane by operating the knee joint and the ankle joint based on instructions from the control unit, the tip force exerted in each direction is measured by the detection unit using the tip force measurement unit. The tip force exertion position estimation unit estimates the tip force exertion position based on the tip force measured by the tip force measurement unit and the moment about an axis perpendicular to the two-dimensional plane detected by the detection unit when the tip force was measured. Each tip force measured by the tip force measurement unit is converted into a joint torque by the torque conversion unit based on the tip force exertion position estimated by the tip force exertion position estimation unit. Based on the joint torque converted by the torque conversion unit, a hexagonal joint torque output distribution with all opposite sides having equal lengths is drawn on the torque plane by the drawing unit. Based on one side of the hexagon of the output distribution drawn by the drawing unit, the muscle group torque estimation unit estimates the muscle group torque of the biarticular calf muscles (posterior biarticular muscles that act on the knee joint and the ankle joint without having an antagonist muscle) of the lower leg. Furthermore, based on another side of the hexagon, the muscle group torque estimator estimates the muscle group torques of the anterior knee muscles (a combination of mono-articular and bi-articular muscles on the front side of the thigh that act on the knee joint) and the posterior knee muscles (a combination of mono-articular and bi-articular muscles on the back side of the thigh that act on the knee joint in antagonism with the anterior knee muscles). Furthermore, based on the remaining side of the hexagon, the muscle group torque estimator estimates the muscle group torques of the anterior foot muscles (anterior mono-articular muscles that act on the ankle joint) and the posterior foot muscles (posterior mono-articular muscles that act on the ankle joint in antagonism with the anterior foot muscles). In this way, even if the position at which the tip force exerted by the knee joint and the ankle joint is exerted changes depending on the direction in which it is exerted, the muscle forces of the five muscle groups of the lower leg can be estimated by estimating the position at which the tip force is exerted from the measured tip force, converting it into joint torque, and plotting the joint torque output distribution of a hexagon with all opposite sides of equal length. That is, there is an effect that it is possible to estimate the muscle strength of each muscle group in the lower leg that is classified by function.

[0022] The muscle strength estimation device according to the second aspect of the present invention achieves the following effect in addition to the effect achieved by the muscle strength estimation device according to the first aspect. That is, the subject exerts a tip force with the foot fixed to the fixing part by covering it. The tip force is detected by a detection unit fixed to the bottom of the fixing part. This allows the subject to reliably exert a tip force on the fixing part from the foot fixed to the fixing part. The tip force exerted on the fixing part can then be reliably detected by the detection unit fixed to the bottom of the fixing part. Therefore, there is an effect that the muscle strength of each muscle group classified by function in the lower leg can be accurately estimated from the reliably detected tip force.

[0023] The muscle force estimation device according to the third aspect of the present invention achieves the following effect in addition to the effect achieved by the muscle force estimation device according to the second aspect. That is, assuming that the distal end force measured by the distal end force measurement unit is exerted at each position on the fixed part, the distal end force exertion position estimation unit calculates the moment about the axial direction orthogonal to the two-dimensional plane for each position. The distal end force exertion position estimation unit then estimates the position at which the calculated moment is closest to the moment about the axial direction orthogonal to the two-dimensional plane detected by the detection unit as the distal end force exertion position. This allows for accurate estimation of the distal end force exertion position on the fixed part, resulting in the effect of more accurately estimating the muscle strength of each muscle group classified by function in the lower leg.

[0024] The muscle strength estimation device according to the fourth aspect of the present invention achieves the following effect in addition to the effects achieved by the muscle strength estimation device according to the second or third aspect. That is, the position of the fixed part is adjusted in at least the direction connecting the knee joint and the ankle joint of the subject in accordance with the physique of the subject so that a distal end force can be reliably exerted on the fixed part. This allows the subject to reliably exert a distal end force on the fixed part based on each muscle group regardless of physique, thereby achieving the effect of more accurately estimating the muscle strength of each muscle group classified by function in the lower leg.

[0025] The muscle strength estimation device according to the fifth aspect of the present invention achieves the following effect in addition to the effect achieved by the muscle strength estimation device according to any one of the first to fourth aspects. That is, when a hexagonal joint torque output distribution is depicted on a torque plane, a constraint is added that the maximum joint torque measurement points identified corresponding to each side of the hexagon are included on or inside each side of the hexagon. As a result, the hexagonal joint torque output distribution is depicted including the maximum joint torque measurement points, which has the effect of enabling reliable estimation of the maximum muscle strength of each muscle group.

[0026] The muscle strength estimation device according to the sixth aspect of the present invention achieves the following effect in addition to the effect achieved by the muscle strength estimation device according to any one of the first to fifth aspects. That is, a distal end force is exerted on the subject in at least the directions of knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion, and each distal end force is measured by the distal end force measuring unit. This has the effect of reliably measuring the distal end forces exerted by the muscle strength of each functionally classified muscle group in the lower limb, and accurately estimating the muscle strength of each muscle group.

[0027] The muscle force estimation device according to the seventh aspect of the present invention achieves the following effect in addition to the effect achieved by the muscle force estimation device according to any one of the first to sixth aspects. A first chart showing the magnitude and direction of the tip force detected by the detection unit in real time is displayed on the display unit by the first monitor display control unit. When the tip force measurement unit exerts a tip force on the subject in a certain direction, the first chart displays a guideline for the direction in which the tip force will be exerted relative to the certain direction by the first guideline display control unit. This allows the subject to exert a tip force in a certain direction so that the current magnitude and direction of the tip force displayed in real time on the first chart matches the guideline for the direction in which the force will be exerted relative to the certain direction displayed on the first chart. Therefore, the tip force can be measured after the subject reliably exerts a tip force in the desired direction, thereby achieving the effect of accurately estimating the muscle strength of each muscle group.

[0028] The muscle force estimation device according to the eighth aspect of the present invention achieves the following effect in addition to the effect achieved by the muscle force estimation device according to any one of the second to fourth aspects. That is, a second chart showing the tip force exertion position estimated by the tip force exertion position estimation unit in real time, together with the shape of the fixation part, is displayed on the display unit by the second monitor display control unit. When the tip force measurement unit exerts a tip force on the subject in one direction, the second chart displays a guideline for the tip force exertion position relative to the one direction through the second guideline display control. As a result, when exerting a tip force in one direction, the subject can exert the tip force so that the current tip force exertion position relative to the shape of the fixation part displayed in real time on the second chart matches the guideline for the force exertion position relative to the one direction displayed on the second chart. Therefore, since the tip force can be measured after the subject reliably exerts the tip force at the desired tip force exertion position, there is an effect that the muscle strength of each muscle group can be accurately estimated.

[0029] The muscle strength estimation device according to the ninth aspect of the present invention achieves the following effect in addition to the effect achieved by the muscle strength estimation device according to any one of the first to eighth aspects. That is, the maximum values ​​of the joint torques in each direction of knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion converted by the torque conversion unit are displayed on the display unit by the joint torque display control unit. This makes it possible to determine whether a tip force is being reliably exerted from the maximum values ​​of the joint torque in each direction displayed on the display unit. This has the effect of making it possible to determine whether the muscle strength of each muscle group is being estimated accurately.

[0030] According to a muscle force estimation method according to a tenth aspect of the present invention, a tip force measuring step causes a test subject to exert tip forces in multiple directions in a two-dimensional plane, thereby measuring the tip forces exerted in each direction. A tip force exertion position estimating step estimates a tip force exertion position based on the tip forces measured in the tip force measuring step and moments about an axis orthogonal to the two-dimensional plane when the tip forces are measured. Each tip force measured in the tip force measuring step is converted into a joint torque in a torque conversion step based on the tip force exertion position estimated in the tip force exertion position estimating step. Based on the converted joint torque, a hexagonal joint torque output distribution, all of whose opposite sides have the same length, is drawn on the torque plane in a drawing step. A muscle group torque of the biarticular calf muscles (posterior biarticular muscles acting on the knee joint and the ankle joint without having an antagonist muscle) of the lower leg is estimated in a muscle group torque estimating step based on one side of the hexagon of the output distribution drawn in the drawing step. Furthermore, based on another side of the hexagon, the muscle group torques of the anterior knee muscles (a combination of mono-articular and bi-articular muscles on the front side of the thigh that act on the knee joint) and the posterior knee muscles (a combination of mono-articular and bi-articular muscles on the back side of the thigh that act on the knee joint in antagonism with the anterior knee muscles) are estimated in a muscle group torque estimation step. Furthermore, based on the remaining side of the hexagon, the muscle group torques of the anterior foot muscles (anterior mono-articular muscles that act on the ankle joint) and the posterior foot muscles (posterior mono-articular muscles that act on the ankle joint in antagonism with the anterior foot muscles) are estimated in a muscle group torque estimation step. In this way, even if the position at which the tip force exerted by the knee joint and the ankle joint is exerted changes depending on the direction in which it is exerted, the muscle forces of the five muscle groups of the lower leg can be estimated by estimating the position at which the tip force is exerted from the measured tip force, converting it into joint torque, and plotting the joint torque output distribution of a hexagon with all opposite sides of equal length. That is, there is an effect that it is possible to estimate the muscle strength of each muscle group in the lower leg that is classified by function. [Brief explanation of the drawings]

[0031] [Figure 1] This is a diagram showing a five-muscle model of the lower leg based on functional effective muscle theory. [Figure 2] FIG. 10 is a diagram illustrating parameters of the lower leg and the foot. [Figure 3] FIG. 1 is a diagram showing the output distribution of joint torque determined by muscle group torque on a torque plane. [Figure 4] FIG. 1(a) is a perspective view showing the schematic configuration of a muscle strength estimation device according to one embodiment of the present invention, FIG. 1(b) is an enlarged view of a boot and a detection unit used in the muscle strength estimation device, and FIG. 1(c) is a diagram illustrating a mechanism for adjusting the position of the boot. [Figure 5] 10 is a flowchart showing a muscle strength estimation process executed by a control unit of the muscle strength estimation device. [Figure 6] 10A and 10B are diagrams schematically showing directions in which a tip force is exerted by a subject in the muscle force estimation process. [Figure 7] 10 is a flowchart showing a monitor display process executed by the control unit. [Figure 8] FIG. 2 is a diagram schematically illustrating a screen displayed on a display unit. [Figure 9] 10 is a flowchart showing a measurement mode process executed by the control unit. [Figure 10] 10(a) is a diagram showing how the position at which the tip force is exerted changes depending on the direction in which the tip force is exerted, and FIG. 10(b) is a diagram showing the shape function representing the shape of the inside of the boot and the moment around the z-axis generated by the tip force. [Figure 11] (a) is a diagram plotting the measurement results of all tip forces measured in each direction of knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion, which were set as the directions in which tip forces would be exerted, and (b) is a diagram showing the tip force exertion positions estimated for each tip force plotted in (a). [Figure 12] 10 is a flowchart showing a joint torque output distribution drawing process executed by the control unit. [Figure 13] 10A and 10B are diagrams illustrating a method for drawing the joint torque output distribution by the joint torque output distribution drawing process. [Figure 14](a) is a diagram depicting a hexagonal output distribution by plotting all joint torques obtained by converting the results of tip force measurements on a torque plane, and (b) is a diagram showing the output distribution of hexagonal joint torque optimized so that the lengths of the opposite sides are equal by applying only constraint (2) in equation (6). [Figure 15] Applying the constraints (2) and (3) in Equation 6, the output distribution of the joint torque T of a hexagon optimized so that the lengths of the opposite sides are equal is shown. [Figure 16] (a) is a diagram showing the link lengths and measurement postures of two adult male subjects, and (b) is a diagram showing the moment arm values ​​of the gastrocnemius, a biarticular muscle group of the lower leg. The diagram also shows the torques Ts of five muscle groups of subjects 1 and 2 estimated by the muscle strength estimation device, as well as the knee extension torque, dorsiflexion torque, knee flexion torque, and plantar flexion torque measured by CybexNorm. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Each of the embodiments described below illustrates a preferred specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component placement and connection configurations, etc., shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not recited in the independent claims that represent the highest concept of the present invention will be described as optional components. Furthermore, in each drawing, substantially identical components are assigned the same reference numerals, and redundant explanations will be omitted or simplified.

[0033] <1. Functional Effective Muscle Theory> <1.1. Five-muscle model of the lower leg> First, the functional effective muscle theory that forms the background of the present invention will be described with reference to Fig. 1. Fig. 1 is a diagram showing a five-muscle model of the lower leg based on the functional effective muscle theory. Fig. 2 is a diagram explaining the parameters of the lower leg and foot.

[0034] In functional effective muscle theory, the muscles of the lower leg are classified into five functional groups that have an effect on movement within a two-dimensional plane that includes the knee joint J2, the ankle joint J3, and the distal force application position TP where distal force F is applied to the distal end of the foot by the knee joint J2 and the ankle joint J3, as shown in Figure 1. Specifically, the five muscle groups are the anterior knee muscles e2, the posterior knee muscles f2, the anterior foot muscles e4, the posterior foot muscles f4, and the biarticular muscles of the calf f5.

[0035] The anterior knee muscles e2 act on the knee joint J2 and are a combination of mono-articular and bi-articular muscles on the front side of the thigh that are connected to the lower leg via the knee joint J2. The posterior knee muscles f2 act on the knee joint J2 in opposition to the anterior knee muscles e2 and are a combination of mono-articular and bi-articular muscles on the back side of the thigh that are connected to the lower leg via the knee joint J2.

[0036] The anterior foot muscle group e4 is a mono-articular muscle on the anterior side that acts on the ankle joint J3. The posterior foot muscle group f4 is a mono-articular muscle on the posterior side that acts on the ankle joint J3 in antagonism to the anterior foot muscle group e4. The bi-articular calf muscle group f5 is a bi-articular muscle on the posterior side that acts on the knee joint and the ankle joint without having an antagonist muscle. Here, the front side of the body is defined as the anterior side, and the back side of the body is defined as the posterior side.

[0037] The distal force F exerted at the distal force exertion position TP by the action of each muscle group s (s=e2, f2, e4, f4, f5) s The direction of is determined by the subject's posture.

[0038] That is, the tip force F based on the action of the anterior knee muscle group e2 e2 and the tip force F based on the action of the posterior knee muscles f2 f2 The direction of the force F is the direction of the line connecting the ankle joint J3 and the tip force exertion position TP. e4 and the tip force F based on the action of the posterior foot muscles f4. f4 The direction of the force F is the direction of the straight line connecting the knee joint J2 and the tip force exertion position TP. e5When the moment arms are equal at both ends of the knee joint J2 and the ankle joint J3, the direction of the arrow (X) is the direction of a straight line connecting the knee joint J2 and the ankle joint J3.

[0039] However, when the distal force F is exerted in the knee extension direction (Fig. 2) where the action of the anterior knee muscles e2 is dominant, the distal force exertion position TP is on the toe side of the foot (see Fig. 11(b)). When the distal force F is exerted in the knee flexion direction (Fig. 2) where the action of the posterior knee muscles f2 and the biarticular calf muscles f5 is dominant, the distal force exertion position TP is on the heel side of the foot (see Fig. 11(b)). When the distal force F is exerted in the foot dorsiflexion direction (Fig. 2) where the action of the anterior foot muscles e4 is dominant, the distal force exertion position TP is on the instep side of the foot (see Fig. 11(b)). When the distal force F is exerted in the plantar flexion direction (Fig. 2) where the action of the posterior foot muscles f4 and the biarticular calf muscles f5 is dominant, the distal force exertion position TP is on the plantar side of the foot (see Fig. 11(b)).

[0040] In this way, the tip force exertion position TP moves depending on the exertion direction of the tip force F, so in the five-muscle model of the lower leg based on functional effective muscle theory, the output distribution of the tip force F cannot be depicted as a hexagon, as in the three-to-six muscle model of the thigh in which the tip force exertion position TP is fixed. Therefore, the muscle force f of each muscle group s in the five-muscle model of the lower leg s The estimation of muscle strength of each muscle group in a 3:6 thigh muscle model, as described in Patent Documents 1 and 2, cannot be performed using the technique.

[0041] In the following description of one embodiment of the present invention, the length (link length) between the knee joint J2 and the ankle joint J3 is defined as l2, the length between the ankle joint J3 and the tip force application position TP is defined as l3, and the angle formed by these links is defined as θ3, as shown in Figure 2. θ2 shown in Figure 2 is the knee joint angle based on the line segment connecting the hip joint and the knee joint J2.

[0042] <1.2. Output distribution of joint torque T> Here, the muscle group torque T generated by the action of each muscle group s is s Figure 3 shows the muscle group torque T sThis is a diagram showing the output distribution of the joint torque T determined by on a torque plane.

[0043] The horizontal axis of the torque plane shown in FIG. 3 is the joint torque (knee torque) T knee The direction of knee extension shown in Figure 2 is taken as positive. The vertical axis of this torque plane is the joint torque (foot torque) T ankle The direction of dorsiflexion of the foot shown in Figure 2 is considered positive.

[0044] Muscle group torque T s is expressed as a vector in the torque plane. The anterior knee muscle torque T corresponding to the anterior knee muscle e2 is e2 The direction of the knee torque T knee The torque T of the posterior knee muscles corresponding to the posterior knee muscles f2 is directed in the positive direction on the axis of f2 The direction of the knee torque T knee It points in the negative direction on the axis.

[0045] Anterior foot muscle group torque T corresponding to anterior foot muscle group e4 e4 The direction of the foot torque T ankle The torque T of the posterior foot muscles corresponding to the posterior foot muscles f4 is directed in the positive direction on the axis of f4 The direction of the foot torque T ankle The biarticular lower leg muscle group f5 generates a negative knee torque T knee and negative foot torque T ankle It is expressed as a composite vector of

[0046] Muscle group torque T s The magnitude of the muscle strength f of muscle group s s Moment arm A s That is, the muscle group torques T corresponding to the front knee muscles e2, the rear knee muscles f2, the front foot muscles e4, and the rear foot muscles f4 can be calculated by multiplying e2 ,T f2 ,T e4 ,T f4 is calculated by the following equation 1.

[0047]

number

[0048] In addition, the torque Tf5 of the biarticular muscle group f5 of the calf is expressed by the moment arms on the knee side and the foot side, respectively. 5knee and A f5ankle Then, it can be expressed by the following equation 2.

[0049]

number

[0050] The output distribution of the joint torque T shown in Figure 3 is the joint torque T=[T knee ,T ankle ] T This shows the range of torque that can be exerted by each muscle group s. s is obtained by adding the vectors together.

[0051] In the hexagon shown in Figure 3, the lengths of sides AB and DE are the same as the lengths of the front knee muscle group torque T of the front knee muscle group e2. e2 The magnitude of the torque T of the posterior hamstrings f2 f2 The magnitude of the torque is the sum of the magnitude of the anterior knee muscle torque T e2 and posterior knee muscle torque T f2 The length of the sides BC and EF is the same as the torque T e4 and the torque T of the posterior foot muscles f4 f4 The slope of the magnitude of the torque of the anterior leg muscles T e4 and posterior foot muscle torque T f4 is the same as

[0052] On the other hand, since there is no antagonist muscle of the biarticular calf muscle group f5 in the sides CD and FA, their lengths are calculated by the equation 2. f5 The magnitude is the same as that of the torque of the biarticular muscles of the lower leg T f5 is the same as

[0053] From the above, the output distribution of the joint torque T can be defined as a hexagon with all opposite sides parallel and of equal length. Specifically, the sides AB and DE of the hexagon of the output distribution of the joint torque T are e2 and posterior knee muscle torque T f2 The sides BC and EF are equal to the combined torque of the front foot muscles T e4 and the posterior foot muscle torque T f4 The sides CD and FA are equal to the combined torque of the biarticular muscles of the lower leg T f5 can be defined as being equal to

[0054] Therefore, the tip force F exerted in each direction at the tip of the foot by the subject operating the knee joint J2 and ankle joint J3 is measured, the measured tip force F is converted into joint torque T, and the converted joint torque T is plotted on a torque plan. Then, by drawing the output distribution of the joint torque T in a hexagon with all opposite sides of equal length, the muscle group torque T for each muscle group s can be calculated from each side of the hexagon. s Then, the estimated muscle torque T s From equations 1 and 2, the muscle strength f of each muscle group is calculated. s can be estimated.

[0055] <2. Muscle strength estimation device> <2.1. Outline configuration> Next, the schematic configuration of a muscle strength estimation device 1 according to one embodiment of the present invention will be described with reference to Fig. 4. Fig. 4(a) is a perspective view showing the schematic configuration of the muscle strength estimation device 1, and Fig. 4(b) is an enlarged view of a boot 16 and a detection unit 17 used in the muscle strength estimation device 1. Fig. 4(c) is a diagram illustrating a mechanism for adjusting the position of the boot 16.

[0056] The muscle strength estimation device 1 is a device that uses the muscle strength estimation method of the present invention to estimate the muscle strength of a subject's lower limbs by dividing it into five muscle groups e2, f2, e4, f4, and f5 shown in Figure 1, which are classified by function based on the functional effective muscle theory.

[0057] The muscle strength estimation device 1 includes a seating section 10 on which the subject can sit in a posture that allows the subject to correctly exert a distal end force F, a detection section 17 that can detect the distal end force F exerted by the subject, a control section 20 that prompts the subject to exert the distal end force F in a predetermined direction and estimates the muscle group torque Ts of each muscle group s based on the distal end force F detected by the detection section 17, and a display section 21.

[0058] The seating portion 10 is configured to include at least a back seat 11, a seat surface 12, a waist belt 18, a thigh belt 19, a leg support 13, a boot position adjusting member 14, a boot support plate 15, and boots 16.

[0059] The back sheet 11 is a seat that supports the waist and back of the seated subject from the back side. The seating surface sheet 12 is a seat that supports the thighs of the seated subject from the seat surface side. The back sheet 11 is configured so that the inclination angle relative to the seating surface sheet 12 can be adjusted. The back sheet 11 is also configured so that it can be adjusted in the front-to-back direction relative to the seating surface sheet 12 as seen from the seated subject. By adjusting the inclination angle and position of the back sheet 11 relative to the seating surface sheet 12 to suit the physique of the subject, the subject can reliably exert the tip force F. Note that if the back sheet 11 cannot be adjusted in the front-to-back direction, a cushion or the like can be inserted between the back sheet 11 and the subject's waist to adjust the position where the subject sits.

[0060] The waist belt 18 is a two-point belt attached to the back seat 11, and is intended to restrict movement of the waist of a subject seated on the seating portion 10. The waist belt 18 is composed of a tongue plate portion 18a and a buckle portion 18b. The tongue plate portion 18a has a tongue plate attached to one end thereof, and the other end thereof is fixed to the lower left part of the back seat 11 as seen from the seated subject via a belt portion. The tongue plate portion 18a also has a function for adjusting the belt length. The buckle portion 18b has a buckle attached to one end thereof that can engage the tongue plate, and the other end thereof is fixed to the lower right part of the back seat 11 as seen from the seated subject via a belt portion.

[0061] The waist belt 18 is used by adjusting the belt length with the tongue plate portion 18a, and by inserting the tongue plate of the tongue plate portion 18a into the buckle of the buckle portion 18b, so that the waist of the subject seated on the seating portion 10 does not move. With this waist belt 18, the subject can exert a tip force F on the boots 16, which will be described later, by using only the five muscle groups s of the lower leg, without moving their waist.

[0062] Thigh belts 19 are two sets of two-point belts attached to seat cushion 12, and are intended to restrict movement of the left and right thighs of a subject seated on seating portion 10. Thigh belt 19 comprises one set of belts made up of tongue plate portion 19a and buckle portion 19b, which restricts movement of the subject's right thigh. Thigh belt 19 also comprises another set of belts made up of tongue plate portion 19c and buckle portion 19d, which restricts movement of the subject's left thigh. The configurations of tongue plates 19a, 19c and buckle portions 19b, 19d are the same as those of tongue plate portion 18a and buckle portion 18b of waist belt 18, respectively. However, the other ends of the tongue plate portions 19a and 19c are each fixed to the front center portion of the seat cushion 12, the other end of the buckle portion 19b is fixed to the front right portion of the seat cushion 12, and the other end of the buckle portion 19d is fixed to the front left portion of the seat cushion 12.

[0063] Thigh belt 19 is used by adjusting the belt length using tongue plate portions 19a, 19c and inserting the tongue plates of tongue plate portions 19a, 19c into the corresponding buckles of buckle portions 19b, 19d to lock the tongue plates into the buckles so that the left and right thighs of the subject seated on seat portion 10 do not move up and down. When the subject exerts distal end force F, using thigh belt 19 restricts movement of the subject's left and right thighs, making it difficult for force to be applied from the hip joint to the thighs, and allowing only five muscle groups s related to the knee joint J2 and ankle joint J3 to act, thereby exerting distal end force F on boots 16, which will be described later.

[0064] A belt (knee restraint) for suppressing upward movement of the knee joint J2 may be provided on the knee joint J2 side of the thigh belt 19. For example, when exerting a tip force F in the plantar flexion direction, the subject exerts the tip force F by stepping downward with the ball of the foot while raising the heel. However, when the knee is raised, hip joint force is applied, making it impossible to exert tip force F by only using the five muscle groups s related to the knee joint J2 and ankle joint J3. By providing a knee restraint, the knee can be prevented from rising, and tip force F can be exerted by only using the five muscle groups s related to the knee joint J2 and ankle joint J3. Furthermore, by raising the heel while pushing back against the knee restraint, it becomes easier to exert tip force F in the foot measurement direction.

[0065] Leg support 13 supports the upper parts of the lower legs of a subject seated on seat 10 from behind, and its upper part is connected via rotating member 13a to the front side of seating sheet 12. Rotating member 13a has a rotation axis provided in the left-right direction as seen from the seated subject, and is configured to rotate within a predetermined range so that the tilt angle of leg support 13 relative to seating sheet 12 can be adjusted, and to be locked at a desired tilt angle.

[0066] The predetermined range is set, for example, as shown in FIG. 4(c), from an inclination angle of 0°, where the surface of the leg support 13 is on the same plane as the seat cushion 12, to an inclination angle of 90°, where the surface of the leg support 13 is perpendicular to the surface of the seat cushion 12 in the knee flexion direction. When the rotating member 13a is locked at an inclination angle of 0°, the subject can sit with their legs extended. When the rotating member 13a is locked at an inclination angle of 90°, the subject can sit with their knee joint J2 bent at a right angle. By adjusting the inclination angle of the leg support 13 to an angle where the subject can reliably exert tip force F, the tip force F exerted by the subject in the boots 16 described below can be reliably detected.

[0067] The boot position adjustment member 14 is a member for adjusting the position of the boot 16. The boot position adjustment member 14 is configured with two pillar members extending from the end of the leg support 13 opposite the rotating member 13a. The two pillar members are attached to the leg support 13 with a predetermined distance between them so that their positions can be adjusted in the left-right direction as seen from the subject seated on the seat 10. A boot support plate 15 is attached to the two pillar members so that it is sandwiched between these pillar members. The boot support plate 15 is a plate-shaped member and is installed on the pillar members so that its wide surface is parallel to a plane perpendicular to the extension direction of the two pillar members. As shown in FIG. 4(b), the boot support plate 15 supports the boot 16 and a detection unit 17 fixed to the bottom of the boot 16 by fixing them to one surface of the plate (the surface facing the seat cushion 12). The boot 16 is fixed to the boot support plate 15 so that its bottom surface is approximately parallel to the boot support plate 15. The boot 16 is also fixed to the boot support plate 15 with a space between it and the boot position adjustment member 14 so that the exerted tip force F is reliably transmitted to the detection unit 17. As shown in Fig. 4(c), the boot support plate 15 is configured so that the mounting position can be adjusted in the extension direction of the pillar member.

[0068] The boot position adjusting member 14 allows the position of the boot support plate 15 to be adjusted in the left-right direction as seen from the subject seated on the seat 10, and in the direction connecting the subject's knee joint J2 and ankle joint J3. This allows the position of the boot 16 fixed to the boot support plate 15 to be adjusted to suit the subject's physique. Therefore, the subject can reliably exert a distal end force F on the boot 16 based on each muscle group s regardless of their physique, and the muscle forces f of the individual muscle groups s classified by function in the lower leg can be adjusted. s can be estimated more accurately.

[0069] Furthermore, the boot position adjustment member 14 can set the position of the boot support plate 15 to either the left or right foot side of the subject seated on the seat 10. Therefore, for one boot 16, the muscle strength of the lower leg of the subject's left foot and the muscle strength of the lower leg of the subject's right foot can be estimated.

[0070] The boot 16 corresponds to the "fixing part" of the present invention and is intended to cover and fix the entire foot of the subject, including at least the toes, instep, sole, and heel from the ankle. The subject seated on the seat 10 can exert a tip force F with the foot fixed to the boot 16 by inserting the foot into the boot 16 fixed to the boot support plate 15.

[0071] Two buckles 16a and 16b are provided side by side on the instep of the boot 16 in the front-to-back direction as seen from the subject seated on the seat 10. The buckles 16a and 16b secure the foot of the subject inserted into the boot 16 so that it does not move within the boot 16.

[0072] By fastening the buckles 16a and 16b, the subject's foot is fixed so as not to move within the boot 16 even if the subject exerts a tip force F on the foot, so the subject can exert only each muscle group s of the five-muscle model to exert the tip force F. Furthermore, the tip force F exerted by the subject can be reliably transmitted to the detection unit 17, and the tip force F can be detected with high accuracy.

[0073] When exerting tip force F in the plantar flexion direction, if buckle 16a on the near side as viewed from the subject is closed, force from the foot is also applied to buckle 16a, which may result in the tip force F not being exerted in the plantar flexion direction. In such a case, it is also possible to open buckle 16a on the near side and close only buckle 16b to measure tip force F.

[0074] The detection unit 17 is configured, for example, by a six-axis force sensor and is fixed to the bottom of the boot 16 via a plate 16c, as shown in FIG. 4(b). The reason for fixing the detection unit 17 to the bottom of the boot 16 via a plate 16c is as follows: Because the bottom surface of the boot 16 is wider than the top surface of the detection unit 17, deformation of the boot 16 may occur if a force is applied to a portion of the boot 16 that protrudes from the detection unit 17. Therefore, such deformation can be suppressed by fixing the detection unit 17 to the bottom of the boot 16 via a plate 16c having a length approximately equal to the length of the boot 16. The surface of the detection unit 17 opposite to the surface fixed to the boot 16 (plate 16c) is fixed to the boot support plate 15, and the bottom surface of the boot 16 is supported by the boot support plate 15 so that it is approximately parallel to the boot support plate 15.

[0075] The detection unit 17 detects the tip force F exerted by the test subject in the boot 16 in two orthogonal axial directions in a two-dimensional plane where movement occurs due to the action of each muscle group s of a five-muscle model based on functional effective muscle theory. The detection unit 17 is connected to the control unit 20 and outputs the detected tip force F to the control unit 20.

[0076] In this embodiment, the direction parallel to the plate-like surface of the boot support plate 15 and extending from the toe position of the foot of the boot 16 to the heel position is defined as the x-axis, and the direction perpendicular to the plate-like surface of the boot support plate 15 is defined as the y-axis. x and the tip force F acting in the y-axis direction y The detection unit 17 detects this and outputs it to the control unit 20.

[0077] The detection unit 17 detects a moment M about a z-axis perpendicular to a two-dimensional plane specified by the x-axis and y-axis, which is a two-dimensional plane in which motion is performed by the action of each muscle group s of a five-muscle model based on functional effective muscle theory. z mea and output it to the control unit 20. This moment M around the z-axis z mea is used to estimate the tip force application position TP, as will be described later.

[0078] Since the detection unit 17 is fixed to the bottom of the boot 16, the distal end force F exerted on the boot 16 can be reliably detected by the detection unit 17. Therefore, the muscle force f of each muscle group s can be calculated from the reliably detected distal end force F. s can be estimated with high accuracy.

[0079] The control unit 20 is configured by a general personal computer, and a detailed description of its configuration will be omitted. The control unit 20 calculates the muscle force f of each muscle group s of a five-muscle model of the lower leg based on a program stored in a storage medium (such as a hard disk drive) built into the personal computer. s Estimate.

[0080] The display unit 21 is configured, for example, by a liquid crystal display, and the display content thereof is controlled by the control unit 20. Note that, although Fig. 4(a) illustrates a case where the control unit 20 and the display unit 21 are configured as separate units, the display unit 21 may be built into the control unit 20, as in a notebook personal computer.

[0081] <2.2. Control of the control unit> <2.2.1. Muscle strength estimation processing> Next, the muscle force estimation process executed by the control unit 20 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a flowchart showing the muscle force estimation process executed by the control unit 20. Fig. 6 is a diagram schematically showing the direction in which the subject is made to exert a tip end force F in the muscle force estimation process. In Fig. 6, the horizontal axis indicates the x-axis which is parallel to the plate-like surface of the boot support plate 15 and points from the toe position of the foot of the boot 16 to the heel position, and the vertical axis indicates the y-axis which is perpendicular to the plate-like surface of the boot support plate 15. Furthermore, in Fig. 6, the numbers in parentheses ((1) to (4)) indicate the order in which the subject is made to exert the tip end force F.

[0082] The muscle strength estimation process involves estimating the muscle strength f of each muscle group s in the five-muscle model of the subject's lower leg. sThis is a process for estimating the muscle strength of the lower legs, and is started when an instruction to estimate the muscle strength of the lower legs is given to the control unit 20. The muscle strength estimation process is executed on the assumption that the subject is seated on the seat 10, with the waist secured by the waist belt 18 and the thighs secured by the thigh belt 19, and the feet inserted into the boots 16 and secured by the buckles 16a and 16b. If necessary, the upper parts of the knees may be secured by knee clamps, and the buckle 16a may be left open.

[0083] When the control unit 20 starts the muscle strength estimation process, it first calculates the muscle strength f of each muscle group s. s The control unit 20 receives input of the subject's parameters necessary to estimate (S1). Specifically, the control unit 20 receives input of the link length l1 between the hip joint and knee joint J2 of the subject, the link length l2 between the knee joint J2 and ankle joint J3, the hip joint flexion angle θ1 based on an upright position, and the knee joint angle θ2 based on a line segment connecting the hip joint and knee joint J2 from a keyboard (not shown) connected to the control unit 20. In addition to the subject's parameters, the control unit 20 also receives input of a correction value for the tilt of the sensor of the detection unit 17 in the process of S1.

[0084] Next, the control unit 20 sets the force application direction to the knee extension direction (S2). That is, the control unit 20 controls the subject to first apply the distal end force F in the knee extension direction shown in FIG. 6. Next, the control unit 20 detects the distal end force F output from the detection unit 17. x ,F y , and moment M z mea Gravity correction value FG for the force in the x-axis direction to perform gravity correction for x , gravity correction value FG for the force in the y-axis direction y , gravity correction value of moment around z axis MG z The tip force F obtained from the detection unit 17 is acquired (S3). x ,F y and moment M z mea The gravity correction value FG for the force in the x-axis direction is x , gravity correction value FG for the force in the y-axis direction y, gravity correction value of moment around z axis MG z The tip force F obtained from the detection unit 17 x ,F y , moment M z mea In the process of S3, the examiner prompts the examinee to relax, and then the examiner presses (inputs) a predetermined key (for example, the "." key) on the keyboard connected to the control unit 20. The force in the x-axis direction, the force in the y-axis direction, and the moment around the z-axis output from the detection unit 17 at that time are converted into gravity correction values ​​FG x , gravity correction value FG for the force in the y-axis direction y , gravity correction value of moment around z axis MG z The gravity correction value is also acquired when the practice mode is switched to the measurement mode (the process of S31 in the measurement mode process (S5, see FIG. 9)).

[0085] Next, the control unit 20 executes a practice processing mode (S4) to provide a practice mode in which the subject practices exerting the tip force F in the set force exertion direction. In the practice mode, the same processes as those in S32 to S35 of the measurement mode processing (S5, see FIG. 9) described later are repeatedly executed to measure the tip force F exerted by the subject and estimate the tip force exertion position TP. The control unit 20 then displays the measured direction and magnitude of the tip force F and the tip force exertion position TP on the display unit 21 described later in a chart together with a guide 32 for the set tip force exertion direction and a guide 35 for the tip force exertion position TP (see FIG. 8). This allows the subject to exert the tip force F while visually observing the display unit 21 in the practice mode before executing the measurement mode, and to confirm how to exert the tip force F relative to the set force exertion direction and the tip force exertion position TP.

[0086] Next, the control unit 20 executes measurement mode processing to execute a measurement mode in which the tip force F exerted by the subject in the set force exertion direction is measured, the measured tip force F is converted into a joint torque T, and the result is stored in a storage medium of the control unit 20 (S5). The transition from practice mode to measurement mode is performed when the measurer prompts the subject to temporarily relax their muscles, and then presses (inputs) a predetermined key (for example, the "." key) on a keyboard connected to the control unit 20. Details of this measurement mode will be described later with reference to FIG. 9.

[0087] Next, the control unit 20 determines (S6) what was input from the keyboard connected to the control unit 20 (which key was pressed) as an instruction to end the measurement mode process (S5). Details will be described later in the description of the measurement mode process (S5), but the key that serves as the instruction to end the measurement mode process (S5) differs depending on the set force direction. For example, if the determination in S6 shows that "1" was input (pressed) as the end instruction (S6: "1"), this means that measurement of the force direction in the knee extension direction has ended, so the next force direction is set to the foot dorsiflexion direction (S7), and the process returns to S4. Also, if the determination in S6 shows that "2" was input as the end instruction (S6: "2"), this means that measurement of the force direction in the foot dorsiflexion direction has ended, so the next force direction is set to the knee flexion direction (S8), and the process returns to S4. Furthermore, if the result of the judgment in S6 is that "3" has been input as an end instruction (S6: "3"), this means that measurement of the knee flexion direction as the force exertion direction has ended, so the next force exertion direction is set to plantar flexion (S9) and processing returns to S4.

[0088] As a result, the control unit 20 can make the subject exert the distal end force F in the order of knee extension direction → foot dorsiflexion direction → knee flexion direction → foot plantar flexion direction as shown in Fig. 6, and detect (measure) the distal end force F exerted in each direction. Therefore, the muscle forces f of the individual muscle groups s functionally classified in the lower limbs can be calculated. s The force F exerted by the muscle group s can be measured reliably, and the muscle force f sIt should be noted that the processes of S2 and S6 to S9 correspond to "exerting the tip force on the subject in a plurality of directions in the two-dimensional plane" in the "tip force measuring unit" and "tip force measuring step" of the present invention.

[0089] Furthermore, if a slash ( / ) has been input as an end command (S6: " / ") as a result of the determination in S6, this means that measurement has ended in all force application directions. Therefore, the control unit 20 executes a joint torque output distribution drawing process (S10) to draw an output distribution of the joint torque T based on all joint torques T corresponding to the tip force F measured in each direction by the measurement mode process (S5). The control unit 20 then estimates the muscle group torque Ts of each muscle group s of the five-muscle model of the lower leg from the hexagon of the joint torque output distribution drawn in the process of S10 (S11), and ends the muscle force estimation process. The joint torque output distribution drawing process (S10) corresponds to the "drawing unit" and "drawing step" of the present invention. Details of the joint torque output distribution drawing process (S10) will be described later with reference to FIG. 12. The process of S11 corresponds to the "muscle group torque estimating unit" and "muscle group torque estimating step" of the present invention. The estimation of the muscle group torque Ts in S11 will be described later with reference to FIG. 3.

[0090] <2.2.2. Monitor display processing> Next, the monitor display process executed by the control unit 20 will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a flowchart showing the monitor display process executed by the control unit 20. Fig. 8 is a diagram schematically showing a screen displayed on the display unit 21 as a result of the control unit 20 executing the monitor display process.

[0091] The monitor display process is a process that is repeatedly executed by the control unit 20 in parallel with the muscle strength estimation process at predetermined time intervals (e.g., 5 milliseconds) while the control unit 20 is executing the muscle strength estimation process, and is a process for displaying on the display unit 21 the status of the tip force F exerted by the subject.

[0092] When the control unit 20 starts executing the monitor display process, it first displays the current mode related to the measurement of the tip force F in the mode display area 38 provided in the upper left of the screen (S21). That is, when the control unit 20 is executing S4 of the muscle strength estimation process (FIG. 5) and is in the practice mode, it displays "practice mode" in the mode display area 38. Also, when the control unit 20 is executing S5 of the muscle strength estimation process and is in the measurement mode, it displays "measurement mode" in the mode display area 38. The subject can know whether the mode is currently in the practice mode or the measurement mode from the display in the mode display area 38.

[0093] Next, the control unit 20 displays a guide 32 of the direction of exertion of the tip force F that the subject is desired to exert on the first chart 31 displayed on the display unit 21 based on the force exertion direction set in the muscle strength measurement process (S22). The first chart 31 displays in real time the magnitude and direction of the tip force F exerted by the subject as a tip force vector 33, with the horizontal axis representing the tip force F in the x-axis direction. x The vertical axis is the tip force F in the y-axis direction. y The "F" symbol shown in the first chart 31 indicates the forward direction of the foot (toward the toes). The same applies to the second chart 34 described later. The processing in S22 corresponds to the "first guideline display control unit" of the present invention.

[0094] Next, the control unit 20 displays a guideline 35 of the tip force application position TP where the test subject is desired to apply the force, based on the force application direction set in the muscle strength measurement process, on a second chart 34 shown on the display unit 21 (S23). The second chart 34 shows an approximation of the shape of the boot 16 in a two-dimensional plane where the tip force F should be applied, and displays the tip force application position TP on that shape as a point 36 in real time. The process of S23 corresponds to the "second guideline display control unit" of the present invention.

[0095] Next, the control unit 20 detects and outputs the tip force F in the x-axis direction detected by the detection unit 17. x and the tip force F in the y-axis direction yBased on this, the magnitude and direction of the tip force F exerted by the subject are displayed as a tip force vector 33 on the first chart 31 (S24). The processing of S24 corresponds to the "first monitor display control unit" of the present invention.

[0096] Furthermore, the control unit 20 displays the tip force application position TP applied by the test subject to the boot 16 as a point 36 on the second chart 34 (S25) based on the tip force application position TP estimated in the practice mode process or in the process of S34 of the measurement mode process (S5) described later and shown in Fig. 9. This process of S24 corresponds to the "second monitor display control unit" of the present invention.

[0097] In the practice mode and the measurement mode, the subject visually checks the first chart 31 and the second chart 34 and adjusts the muscle strength of the lower leg so that the tip force vector 33 displayed on the first chart 31 falls within the guideline 32 for the direction in which the tip force F is exerted, and the point 36 displayed on the second chart 34 falls within the guideline 35 for the tip force exertion position TP.

[0098] As a result, when the test subject exerts a tip force F in one direction, the test subject can exert the tip force F so that the magnitude and direction of the current tip force F displayed in real time on the first chart 31 matches the guide 32 for the direction of exertion of the force in one direction displayed on the first chart 31, and so that the current tip force exertion position TP with respect to the shape of the boot 16 displayed in real time on the second chart 34 matches the guide 35 for the tip force exertion position TP in one direction displayed on the second chart 34. Therefore, the tip force F can be measured after the test subject reliably exerts the tip force F in the desired direction.

[0099] Next, the control unit 20 displays in the joint torque display area 37 of the display unit 21, based on the joint torque T converted from the measured tip force F, the maximum joint torque in the knee extension direction T_knee_e_max, the maximum joint torque in the foot dorsiflexion direction T_ankle_d_max, the maximum joint torque in the knee flexion direction T_knee_f_max, and the maximum joint torque in the foot plantar flexion direction T_ankle_p_max (hereinafter these are collectively referred to as "maximum joint torque in the knee extension direction T_knee_e_max, etc.") (S26), and terminates the monitor display processing.

[0100] The joint torque T is obtained by converting the tip force F in the process of S35 of the measurement mode process (S5) described later and shown in Fig. 9. The maximum value T_knee_e_max of the joint torque in the knee extension direction is updated in the process of S37 of the measurement mode process (S5) and stored in the storage medium of the control unit 20.

[0101] By displaying the maximum value of the joint torque in the knee extension direction, T_knee_e_max, etc., on the display unit 21, it is possible to determine whether the distal end force F is being exerted reliably, and the muscle force f of each muscle group s s It can be determined whether the estimation of the tip force F is performed with high accuracy. If it is determined that the tip force F is not being exerted, the measurement of the tip force F can be repeated. The processing of S26 corresponds to the "joint torque display control unit" of the present invention.

[0102] <2.2.3. Measurement mode processing> Next, with reference to Figs. 9 to 11, the measurement mode process (S5), which is one of the muscle force estimation processes shown in Fig. 5 and executed by the control unit 20, will be described in detail. First, Fig. 9 is a flowchart showing the measurement mode process (S5). Fig. 10(a) is a diagram showing how the tip force exertion position TP changes depending on the direction in which the tip force F is exerted, and Fig. 10(b) is a diagram showing how the tip force exertion position TP changes depending on the shape function y=f n (x) and the moment M around the z-axis caused by the tip force F z This is a diagram showing the above.

[0103] When the control unit 20 starts the measurement mode process (S5), first, the control unit 20 detects the tip force F x ,F y , and moment M z mea Gravity correction value FG for the force in the x-axis direction to perform gravity correction for x , gravity correction value FG for the force in the y-axis direction y , gravity correction value of moment around z axis MG z (S31). When switching from practice mode to measurement mode, as described above, the measurer prompts the subject to relax, and then presses (inputs) a predetermined key (for example, the "." key) on the keyboard connected to the control unit 20, which switches to measurement mode and starts measurement mode processing (S5). The processing of S31 converts the force in the x-axis direction, the force in the y-axis direction, and the moment around the z-axis output from the detection unit 17 at that stage into a gravity correction value FG for the force in the x-axis direction. x , gravity correction value FG for the force in the y-axis direction y , gravity correction value of moment around z axis MG z After entering the measurement mode, the examiner instructs the examinee to exert the tip force F in the set force exertion direction.

[0104] Gravity correction can be performed more accurately by acquiring gravity correction values ​​through the process of S31 each time the measurement mode process (S5) is started. Note that if the force application direction is set to knee extension, gravity correction values ​​are acquired through the process of S3 in the muscle strength estimation process, so the process of S31 may be omitted.

[0105] Next, the control unit 20 calculates the tip force F in the x-axis direction exerted in the boot 16 detected by the detection unit 17. x and the tip force F in the y-axis direction y and the moment M around the z-axis generated by the tip force F z mea are acquired from the detection unit 17 (S32).

[0106] Then, the control unit 20 calculates the gravity correction value FG of the force in the x-axis direction most recently acquired. x, gravity correction value FG for the force in the y-axis direction y , gravity correction value of moment around z axis MG z and the tip force F obtained from the detection unit 17 by the process of S32. x ,F y , moment M z mea Gravity correction is performed by subtracting the value after gravity correction from the end force Fx in the x-axis direction and the end force Fy in the y-axis direction, which are detected (measured) by the detection unit 17 and acquired from the detection unit 17, and the moment M around the z-axis generated based on the end force Fx. z mea The processes of S32 and S33 correspond to "measuring the tip forces exerted in each direction by the detection unit" in the "tip force measurement unit" of the present invention, and "measuring the tip forces exerted in each direction in at least two orthogonal axial directions in the two-dimensional plane" in the "tip force measurement step."

[0107] Next, the control unit 20 estimates the tip force exertion position TP (S34). As shown in Fig. 10(a), when the tip force F is exerted in the plantar flexion direction, the tip force exertion position TP is the position of the sole of the foot on the tip side within the boot 16, and when the tip force F is exerted in the knee flexion direction, the tip force exertion position TP is the position of the heel within the boot 16. Although not shown, when the tip force F is exerted in the knee extension direction, the tip force exertion position TP is the position of the toe within the boot 16, and when the tip force F is exerted in the foot dorsiflexion direction, the tip force exertion position TP is the position of the instep within the boot 16.

[0108] In this way, the tip force exertion position TP changes depending on the exertion direction of the exerted tip force F. knee and foot torque T ankle When converting to the tip force F, it is necessary to identify the tip force application position TP, which changes depending on the application direction of the tip force F. The process of S34 estimates the tip force application position TP.

[0109] In the process of S34, first, the tip force F in the x-axis direction obtained from the detection unit 17 is calculated.x and the tip force F in the y-axis direction y From the equation, the moment M around the z-axis z cal is calculated using the following equation 3.

[0110]

number

[0111] Here, the shape function y=f(x) representing the internal shape of the boot 16 is expressed as y=f n (x) (n=1,2,3,4,5) and add f to y in number 3. n Substitute (x). Note that n is determined by the direction in which the tip force F is exerted.

[0112] Then, the moment M around the z-axis calculated by Equation 3 z cal and the moment M around the z-axis actually detected by the detection unit 17. z mea The position (x,f n (x)) is estimated to be the tip force application position TP.

[0113] In this way, assuming that the tip force F measured by the detection unit 17 is exerted at each position of the boot 16, the moment M about the z-axis direction calculated for each position is z cal is the moment M about the z-axis direction detected by the detection unit 17. z mea The position (x,f n (x)) is estimated as the tip force exerting position TP. This makes it possible to accurately estimate the tip force exerting position TP exerted on the boot 16, and as a result, the muscle forces f of the individual muscle groups s classified by function in the lower leg can be estimated. s It should be noted that the processing in S34 corresponds to the "tip force exerting position estimating section" and the "tip force exerting position estimating step" of the present invention.

[0114] Next, the control unit 20 calculates the tip force F=[F x ,F y ] T From the joint torque T=[T knee ,T ankle ] T is converted to using the following equation 4.

[0115]

number

[0116] Here, J T is the transpose matrix of the Jacobian matrix J. The Jacobian matrix J is calculated based on the length l2 between the knee joint J2 and the ankle joint J3, the length l3 between the ankle joint J3 and the tip force exerting position TP, and the angle θ 3、 This is expressed by the following equation 5 using the knee joint angle θ2 based on the line segment connecting the hip joint and the knee joint J2.

[0117]

number

[0118] As shown in Equation 5, the Jacobian matrix J is determined by the length l3 and angle θ3, which change depending on the position of the tip force application position TP. In other words, by accurately estimating the tip force application position TP through the process of S34, the joint torque T can be accurately obtained from the tip force F. The process of S35 corresponds to the "torque conversion unit" and "torque conversion step" of the present invention.

[0119] Next, the control unit 20 stores the joint torque T obtained by the conversion process of S35 in the storage medium of the control unit 20 (S36). The joint torque T stored here is referenced in the joint torque output distribution drawing process (S10) described later with reference to FIG.

[0120] In addition, the control unit 20 updates the maximum values ​​of joint torque in the knee extension direction T_knee_e_max, the maximum value of joint torque in the foot dorsiflexion direction T_ankle_d_max, the maximum value of joint torque in the knee flexion direction T_knee_f_max, and the maximum value of joint torque in the foot plantar flexion direction T_ankle_p_max, which are stored in the storage medium since the start of the muscle strength estimation process, based on the joint torque T obtained by the conversion process in S35, and stores each updated maximum value in the storage medium (S37).

[0121] Specifically, immediately after starting the muscle force estimation process, the control unit 20 stores all zeros as initial values ​​of the maximum joint torque T_knee_e_max in the knee extension direction in the storage medium of the control unit 20. Then, in the process of S37, the control unit 20 compares the joint torques in each direction of knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion obtained from the joint torque T obtained by the conversion process of S35 with the maximum joint torque T_knee_e_max in the knee extension direction stored so far in the storage medium of the control unit 20.

[0122] Then, if the joint torque in any of the directions of knee extension, dorsiflexion, knee flexion, or plantar flexion obtained from the joint torque T obtained by the conversion process of S35 is greater than the maximum value of the joint torque in the knee extension direction up to now stored in the storage medium of the control unit 20, such as T_knee_e_max, the maximum value of the joint torque in the direction determined to be greater is replaced with the value of the joint torque in that direction obtained from the joint torque T obtained by the conversion process of S35.

[0123] The processing of S37 obtains the maximum value T_knee_e_max of the joint torque in the knee extension direction after the start of the muscle force estimation processing. As described above, the maximum value T_knee_e_max of the joint torque in the knee extension direction obtained by the processing of S37 is displayed in the joint torque display area 37 of the display unit 21, and is used to determine whether the tip force F is being reliably exerted.

[0124] Next, the control unit 20 determines whether an instruction to end the measurement mode process (S5) has been given (S38), and if there has been no instruction to end (S38: No), determines whether 5 milliseconds have passed since the tip force F was acquired from the detection unit 17 by the process of S32 (S39). If 5 milliseconds have not passed (S39: No), the control unit 20 repeats the determination of S39, and if 5 milliseconds have passed (S39: Yes), the control unit 20 returns to the process of S32 and executes the processes of S32 to S37 again.

[0125] As a result of the determination in S38, if it is determined that an end instruction has been given (S38: Yes), the control unit 20 ends the measurement mode process (S5) and returns to the muscle force estimation process. As a result, the measurement mode process, in cooperation with the monitor display process, causes the subject to exert a tip force F in the tip force exertion direction set in the muscle force estimation process, in accordance with the tip force exertion direction of the set tip force, acquires the tip force F exerted by the subject every 5 milliseconds, and converts each acquired tip force F into a joint torque T in real time.

[0126] The instruction to end the measurement mode process (S5) is given by pressing (inputting) a predetermined key on a keyboard connected to the control unit 20. For example, if the preset force application direction is the knee extension direction, pressing the "1" key gives an end instruction; if the force application direction is the foot dorsiflexion direction, pressing the "2" key gives an end instruction; if the force application direction is the knee flexion direction, pressing the "3" key gives an end instruction; and if the force application direction is the foot plantar flexion direction, pressing the " / " key gives an end instruction. In the measurement mode process (S5), if it is confirmed that the measurement of the tip force F in the set force application direction was performed without any problems, the force application direction can be ended by pressing a predetermined key.

[0127] 11(a) is a diagram plotting all measurement results of the tip force F measured by the muscle force estimation process in each direction of knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion, which are set as directions for exerting the tip force F. In FIG. 11(a), areas 41 to 44 are measurement results when the tip force F is exerted in the knee extension direction, foot dorsiflexion direction, knee flexion direction, and foot plantar flexion direction, respectively.

[0128] Moreover, Fig. 11(b) is a diagram showing the tip force exertion positions TP estimated by the process of S34 for each tip force F plotted in Fig. 11(a). In Fig. 11(b), regions 41 to 44 correspond to the regions 41 to 44 shown in Fig. 11(a), respectively, and show a set of tip force exertion positions TP estimated from the tip forces F included in the regions of the same reference numerals shown in Fig. 11(a).

[0129] As shown in Figure 11(b), it can be seen that the tip force application position TP varies even when the tip force F is applied in the same direction. The measurement mode process (S5) can calculate the joint torque T with high accuracy by accurately estimating each tip force application position TP as shown in Figure 11(b).

[0130] <2.2.4. Joint torque output distribution drawing process> Next, the joint torque output distribution drawing process (S10), which is one of the processes of the muscle force estimation process of Fig. 5 executed by the control unit 20, will be described in detail with reference to Fig. 12 to Fig. 15. First, Fig. 12 is a flowchart showing the joint torque output distribution drawing process (S10). Fig. 13 is a diagram schematically showing a method for drawing the output distribution of the joint torque T by the joint torque output distribution drawing process.

[0131] In the following description, the terms "drawing" and "plotting" are used, but they do not necessarily refer to physical drawing on paper or a screen, but rather to drawing on a virtually prepared torque plane. The torque plane to be drawn and plotted is the one described with reference to FIG. 3.

[0132] When the control unit 20 starts executing the joint torque output distribution drawing process (S10), first, as shown in FIG. 13(a), all joint torques T stored in the storage medium of the control unit 20 are plotted on a torque plane as measurement points p51 (S41).

[0133] Next, the control unit 20 calculates the maximum measurement point p f that is the furthest from the origin O for each of the sides AB, BC, CD, DE, EF, and FA of the hexagon defined as the output distribution of the joint torque T. max_AB 52, p. max_BC 53, p. max_CD 54, p. max_DE 55, p. max_EF 56, p. max_FA 57 is identified from the measurement points p51 as shown in FIG. 13(a) (S42).

[0134] In addition, in Fig. 13(a), the maximum measurement point p max_AB 52 and the maximum measurement point p for the side BC max_BC Only 53 is shown, and other p max_CD 54, p. max_DE 55, p. max_EF 56, p. max_FA 57 is p. max_AB 52, p. max_BC 53 is shown in Figure 13(b).

[0135] Next, as shown in FIG. 13(b), the control unit 20 determines the maximum measurement points p corresponding to the sides AB, BC, CD, DE, EF, and FA of the hexagon. max_i Passing through 52~57 (i=AB,BC,CD,DE,EF,FA), distance D from origin O i A line segment with the slope shown in FIG. 3 is drawn so that the line is maximized (S43).

[0136] Figure 14(a) is a diagram in which all joint torques T obtained by converting the measurement results of the tip force F shown in Figure 11(a) are plotted on a torque plane as measurement point p51, and a hexagonal output distribution is drawn by the processes of S42 and S43 above. As shown in Figure 14(a), at this stage, the output distribution characteristic that the lengths of the opposite sides of the hexagon are equal is not satisfied.

[0137] Therefore, in order to obtain a hexagonal output distribution with opposite sides of equal length, the control unit 20 performs optimization using the following equation (6) for the hexagonal output distribution of the joint torque T obtained by the process of S43 (S44). Then, the control unit 20 ends the joint torque output distribution drawing process.

[0138]

number

[0139] where D max_i is the distance between each edge i (i = AB, BC, CD, DE, EF, FA) of the output distribution of the joint torque T obtained by the processing of S43 based on the measured values ​​and the origin O, and d i is the distance between each side i of the output distribution with equal opposite sides newly drawn by the process of S44 and the origin O.

[0140] The condition shown in (2) of equation 6 is a constraint for making the lengths of opposite sides of a hexagon equal. Here, the condition is that the lengths of opposite sides BC and EF are equal, but it is also possible to make the length of any one pair of opposite sides out of the three pairs of opposite sides (AB,DE), (BC,EF), and (CD,FA) equal. Then, if the condition is that the lengths of one pair of opposite sides are equal, then since all opposite sides are parallel, the lengths of the other pairs of opposite sides can also be made equal.

[0141] The condition shown in (3) of Equation 6 is the maximum measurement point p of the joint torque T identified corresponding to each side i of the hexagon. max_i 52 to 57 are constraints for including the points on each side i of the hexagon or inside each side i.

[0142] In the process of S44, under these constraints (2) and (3), the distance D of each side i is calculated as shown in (1) of Equation 6. max_i and distance d i Identify the optimized side i of the hexagon so that the lengths of the opposite sides are equal, such that the sum of the differences between

[0143] Here, Figure 14(b) shows the output distribution of the joint torque T of a hexagon optimized so that the lengths of the opposite sides are equal by removing the constraint (3) and applying only the constraint (2). If the constraint (3) is not set, as shown in Figure 14(b), some measurement points p51 of the joint torque T may be located outside the hexagon. This causes the joint torque T based on the maximum tip force F to be smaller than the muscle group torque T of each muscle group s. s This will deviate from the estimate of the muscle strength f of each muscle group s. s However, there is a risk that the muscle strength will be less than its original level.

[0144] On the other hand, Figure 15 shows the output distribution of the joint torque T of the hexagon, which is optimized so that the lengths of the opposite sides are equal by applying not only the constraint (2) but also the constraint (3). As shown in Figure 15, by applying the constraint (3), the output distribution of the joint torque T of the hexagon is max_i 52 to 57 are always included in the drawing. This allows for reliable estimation of the maximum muscle strength of each muscle group s.

[0145] <2.2.5. Muscle group torque T s Estimate of> As described above, in the muscle force estimation process (FIG. 5), the control unit 20 performs the joint torque output distribution drawing process (S10) to draw the output distribution of the joint torque T in a hexagon with the opposite sides of equal length as shown in FIG. 15, and then calculates the muscle group torque T for each muscle group s using the drawn hexagon. s is estimated (S11).

[0146] Specifically, as shown in Figure 3, the sides CD and FA of the hexagonal output distribution are the torque T f5 Therefore, based on this side CD or side FA, the torque T f5 This side CD or side FA corresponds to "one side of the hexagon" in the present invention.

[0147] Furthermore, as shown by the dashed line in Figure 3, the torque of the biarticular muscles of the lower leg T f5 By drawing a straight line parallel to each side from the tip of the hexagon, the torque T of the front knee muscles e2 is calculated based on the side AB or side DE of the hexagonal output distribution. e2 and the torque T of the posterior knee muscles f2 f2 Furthermore, the torque T of the front leg muscle group e4 can be determined based on the side BC or the side EF of the hexagonal output distribution. e4 and the torque T of the posterior foot muscles f4 f4 It should be noted that side AB or side DE corresponds to "another side of the hexagon" in the present invention, and side BC or side EF corresponds to "the remaining side of the hexagon" in the present invention.

[0148] The control unit 20 calculates the muscle group torque T of each muscle group s estimated in this way. s From the above, by using the relational expressions of Equation 1 and Equation 2, the muscle force f of each muscle group s can be calculated. s can be estimated.

[0149] 3. Effectiveness of the Muscle Force Estimation Device According to the Present Embodiment The applicant produced a prototype of the muscle force estimation device 1 according to the present embodiment and verified its effectiveness. Specifically, as a comparative example, the joint torque T was measured using a CybexNorm joint torque measuring device that has been commonly used to measure muscle force, and the result was compared with the estimation result of the muscle force estimation device 1 according to the present embodiment.

[0150] <3.1.Measurement method> Figure 16(a) shows the link lengths and measurement postures of two adult male subjects. In Figure 16(a), link length l1 is the length between the hip joint and knee joint J2, and was 0.43 m for subject 1 and 0.46 m for subject 2. Link length l2 (the length between the knee joint J2 and ankle joint J3) was 0.39 m for subject 1 and 0.43 m for subject 2.

[0151] The angle θ1 representing the measurement posture is the hip joint flexion angle based on an upright position, and was set to 90° for both Subject 1 and Subject 2. The knee joint angle θ2 based on a line segment connecting the hip joint and knee joint J2 was set to 80° for both Subject 1 and Subject 2. In both the example using the muscle strength estimation device 1 according to this embodiment and the comparative example using the joint torque measuring device CybexNorm, estimation or measurement was performed in the same posture.

[0152] However, in measurements using the muscle strength estimation device 1 according to this embodiment, the foot was inserted into the boot 16, and the two buckles 16a and 16b of the boot 16 were closed to secure the foot inside the boot 16. The waist was secured with a waist belt 18, and the thighs with a thigh belt 19. The subject was asked to exert a distal end force F with their arms crossed in front of their chest. Only when exerting a distal end force F in the plantar flexion direction was a knee clamp additionally attached to make it difficult for the hip joint and thigh to apply force, and only buckle 16a was opened to prevent the instep of the foot from coming into two-point contact with buckle 16b inside the boot 16.

[0153] Figure 16(b) shows the moment arm A of the gastrocnemius muscle, which is a biarticular muscle of the lower leg f5. f5knee and A f5ankle These values ​​were obtained by setting the posture shown in Figure 16(a) for the leg6dof9musc model (height 1.80 m, weight 75.16 kg) published in OpenSim4.1.

[0154] The muscle force estimation by the muscle force estimation device 1 according to the present embodiment was performed three times, with each set consisting of exerting tip forces F in four directions, i.e., knee extension, dorsiflexion, knee flexion, and plantar flexion. The muscle group torques T s The maximum value was used as the comparison value.

[0155] On the other hand, with CybexNorm, the joint torque of the knee joint J2 and the ankle joint J3 was measured with different attachments for each joint during isometric movement in four directions: knee extension, knee flexion, dorsiflexion, and plantar flexion. With CybexNorm, maximum force was exerted three times for three seconds, and the maximum torque of the three force exertions was used.

[0156] <3.2. Measurement results> FIG. 16(c) shows the five muscle group torques T of subjects 1 and 2 estimated by the muscle force estimation device 1 of this embodiment. s The anterior knee muscle torque T e2 , posterior knee muscle torque T f2 , anterior foot muscle torque T e4 , posterior foot muscle torque T f4 , and the torque of the biarticular muscles of the lower leg T f5 13 is a graph showing the knee extension torque, foot dorsiflexion torque, knee flexion torque, and foot plantar flexion torque measured by CybexNorm.

[0157] As shown in FIG. 16(c), the anterior knee muscle torque T e2 and anterior foot muscle torque T e4 For both Subject 1 and Subject 2, the knee extension torque and foot dorsiflexion torque measured by CybexNorm were within a range that could be judged to be equivalent. On the other hand, with CybexNorm, the posterior knee muscle torque T f2 , lower leg biarticular muscle torque T f5 , and posterior foot muscle torque T f4 It is not possible to clearly separate and measure the torque of the biarticular muscles of the lower leg T f5 is measured as being included in the knee flexion torque and plantar flexion torque. In contrast, the muscle strength estimation device 1 according to the present embodiment measures the posterior knee muscle group torque T f2 , lower leg biarticular muscle torque T f5 , and posterior foot muscle torque T f4 In this way, the muscle strength estimation device 1 can estimate the anterior knee muscle torque T e2 and anterior foot muscle torque T e4 can be accurately estimated, and the posterior knee muscle torque Tf2 , lower leg biarticular muscle torque T f5 , and posterior foot muscle torque T f4 That is, the muscle strength estimation device 1 can estimate the muscle strength f of each of the five muscle groups s in the lower leg that are classified by function. s can be estimated and can be said to be valid.

[0158] In addition, CybexNorm requires the user to get on and off the device to change the attachments between measuring the joint torque of the knee joint J2 and the joint torque of the ankle joint J3, which takes time to measure. However, the muscle strength estimation device 1 can measure the muscle strength f of five muscle groups s by simply sitting down once. s Therefore, the muscle strength estimation device 1 is advantageous in terms of ease of measurement and reduction of the burden on the subject.

[0159] <4. Summary> As explained above, the muscle strength estimation device 1 using the muscle strength estimation method of the present invention estimates muscle strength of the lower leg (knee-ankle joint) by dividing the muscles of the lower leg into five muscle groups s classified by function. s The joint torque T generated based on the tip force F acting on the tip force exertion position TP is estimated on the torque plane (one axis is the joint torque T related to the knee joint J2). knee The other axis perpendicular to this axis is the joint torque T ankle This is based on the fact that when the output distribution of the joint torque T is shown on a plane (on which the joint is placed), it becomes a hexagon with the opposite sides of equal length.

[0160] Specifically, based on instructions from the control unit 20, the subject applies a tip force F to the knee joint J2 and the ankle joint J3 in four directions (knee extension, dorsiflexion, flexion, and plantar flexion) in a two-dimensional plane, and the tip force F exerted in each direction is measured by the detection unit 17. This measured tip force F and the moment M about the Z axis perpendicular to the two-dimensional plane detected by the detection unit 17 when the tip force F was measured are z mea Based on this, the tip force exertion position TP is estimated.

[0161] Each of the measured tip forces F is converted into a joint torque T based on the estimated tip force application position TP. Based on the converted joint torque T, a hexagonal output distribution of the joint torque T, with all opposite sides of equal length, is plotted on the torque plane as shown in FIG. 3. Based on the side CD or side FA of the hexagon of the plotted output distribution, the torque T of the biarticular calf muscle group f5 of the lower leg (a posterior biarticular muscle that acts on the knee joint J2 and the ankle joint J3 without having an antagonist muscle) is calculated. f5 In addition, based on the side AB or DE of the hexagon, the front knee muscle group torque T of the front knee muscle group e2 (which acts on the knee joint J2 and is a combination of monoarticular and biarticular muscles on the front of the thigh) is estimated. e2 and the posterior knee muscle torque T of the posterior knee muscle group f2 (which acts on the knee joint J2 in opposition to the anterior knee muscle group e2 and is a combination of monoarticular and biarticular muscles on the posterior side of the thigh) f2 Furthermore, based on the side BC or side EF of the hexagon, the front foot muscle group torque T of the front foot muscle group e4 (the anterior monoarticular muscle acting on the ankle joint J3) is estimated. e4 and the posterior foot muscle group torque T of the posterior foot muscle group f4 (the posterior monoarticular muscle acting on the ankle joint J3 in opposition to the anterior foot muscle group e4). f4 is estimated.

[0162] In this way, even if the tip force F exerted by the knee joint J2 and the ankle joint J3 at the tip force exertion position TP changes depending on the exertion direction, the tip force exertion position TP is estimated from the measured tip force F and converted into joint torque T. By plotting the output distribution of the joint torque T as a hexagon with the same length for all opposite sides, the muscle forces f of the five muscle groups s in the lower leg can be calculated. s In other words, the muscle strength f of each muscle group s classified by function in the lower leg can be estimated. s can be estimated.

[0163] <Modification> Although the present invention has been described above based on the embodiments, it is readily apparent that the present invention is not limited to the above embodiments and that various improvements and modifications are possible within the scope of the present invention. For example, each embodiment may be modified by adding or replacing a part or parts of the configuration of another embodiment, including the modifications described below. Furthermore, the numerical values ​​given in the above embodiments are merely examples, and other numerical values ​​may of course be adopted.

[0164] In the above embodiment, the boot 16 covers and fixes the entire foot of the subject, but it does not necessarily have to cover the entire foot. A fixing member may be used that fixes the foot so as to cover at least the direction in which the tip force F is exerted, i.e., at least the toe, instep, sole, and heel of the foot. The fixing member does not necessarily have to be boot-shaped or shoe-shaped, and may be composed of multiple members. At least one of the multiple members may be a rubber band. By covering and fixing at least one of the toe, instep, sole, and heel with an individual member, the tip force exertion position TP exerted in the corresponding direction can be limited to the inside of that member, making it easier for the subject to exert the tip force F and enabling accurate measurement of the tip force F exerted by the subject.

[0165] In the above embodiment, the case where the direction of exertion of the tip force F to be exerted by the subject is set to four directions, namely, knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion, has been described. However, this is not necessarily limited to this, and any number of directions may be set as long as the five muscle groups s are actuated and a hexagonal joint torque T output distribution can be depicted. Furthermore, in addition to the four directions of knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion, an obliquely upward direction obtained by vectorially adding the knee extension direction and the foot dorsiflexion direction may be added. By increasing the number of directions in which the tip force F is exerted, the hexagonal joint torque T output distribution can be depicted more accurately, and the muscle force f of each muscle group s can be more accurately depicted. s can be evaluated. [Explanation of symbols]

[0166] 1. Muscle strength estimation device 10 Seating area 11 Rear seat 12 Seat 13 Leg Support 13a Rotating member 14 Boot position adjustment member 15 Boot support plate 16 Boots 17 Detection unit 18 Waist belt 19 Thigh belt 20 Control Unit 21 Display section 31 First Chart 34 Second Chart 37 Joint torque display area 51 measurement points 52 maximum measurement points 53 Maximum measurement points 54 maximum measurement points 55 maximum measurement points 56 maximum measurement points 57 Maximum measurement points e2 Anterior knee muscles e4 Anterior foot muscles f2 Posterior knee muscles f4 hindfoot muscle group f5 Biarticular muscles of the lower leg

Claims

1. A muscle strength estimation device that estimates muscle strength of a subject's lower limbs by dividing the muscle strength into five muscle groups classified by function as muscle groups that have an effect on movement in a two-dimensional plane that includes a knee joint, an ankle joint, and a distal end force exertion position where a distal end force is exerted by the knee joint and the ankle joint, The muscle group is The anterior knee muscles, which act on the knee joint and are a combination of monoarticular and biarticular muscles on the front of the thigh, A posterior knee muscle group that acts on the knee joint in opposition to the anterior knee muscle group and is a combination of monoarticular muscles and biarticular muscles on the posterior side of the thigh; The anterior foot muscles are the anterior monoarticular muscles that act on the ankle joint; a posterior foot muscle group, which is a posterior monoarticular muscle acting on the ankle joint in an antagonistic manner to the anterior foot muscle group; a biarticular muscle group of the calves, which is a posterior biarticular muscle acting on the knee joint and the ankle joint without having an antagonist muscle; The muscle strength estimation device includes: A detection unit that detects the tip force exerted at the tip force exertion position by the knee joint and the ankle joint at least in two orthogonal axial directions in the two-dimensional plane and is capable of detecting at least a moment around an axis orthogonal to the two-dimensional plane; a control unit, The control unit a tip force measuring unit that causes the subject to exert the tip force in a plurality of directions in the two-dimensional plane and measures the tip force exerted in each direction with the detection unit; a tip force exertion position estimating unit that estimates a tip force exertion position based on the tip force measured by the tip force measuring unit and a moment about an axis orthogonal to the two-dimensional plane detected by the detecting unit when the tip force is measured; and a torque conversion unit that converts each of the tip forces measured by the tip force measurement unit into a joint torque based on the tip force exertion position estimated by the tip force exertion position estimating unit; a drawing unit that draws, based on the joint torque converted by the torque conversion unit, a hexagonal joint torque output distribution, all of whose opposite sides have the same length, on a torque plane having a joint torque related to the knee joint as one axis and a joint torque related to the ankle joint as another axis perpendicular to the one axis; a muscle group torque estimation unit that estimates the muscle group torque of the biarticular muscles of the calf based on one side of the hexagon of the output distribution drawn by the drawing unit, estimates the muscle group torque of each of the anterior knee muscle group and the posterior knee muscle group based on another side of the hexagon, and estimates the muscle group torque of each of the anterior foot muscle group and the posterior foot muscle group based on the remaining side of the hexagon.

2. A fixing part is provided to cover and fix the foot part, The tip force is exerted in a state where the foot portion is fixed to the fixing portion, The muscle strength estimation device according to claim 1 , wherein the detection unit detects the tip force while being fixed to the bottom of the fixing unit.

3. 3. The muscle force estimation device according to claim 2, wherein the distal end force exertion position estimating unit calculates a moment about an axial direction orthogonal to the two-dimensional plane for each position of the fixed part, assuming that the distal end force measured by the distal end force measuring unit is exerted at that position, and estimates, as the distal end force exertion position, the position at which the calculated moment takes a value closest to the moment about the axial direction orthogonal to the two-dimensional plane detected by the detecting unit.

4. 3. The muscle strength estimation device according to claim 2, wherein the fixing portion is configured so that its position can be adjusted at least in a direction connecting the knee joint and the ankle joint of the subject.

5. The drawing unit The muscle force estimation device according to claim 1, wherein the output distribution of the joint torque of the hexagon is plotted under the constraint that the maximum measurement points of the joint torque specified corresponding to each side of the hexagon are included on or inside each side of the hexagon.

6. 2. The muscle strength estimation device according to claim 1, wherein the tip force measurement unit exerts the tip force on the subject in each of the plurality of directions, at least in knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion.

7. The control unit a first monitor display control unit that causes a display unit to display a first chart that indicates in real time the magnitude and direction of the tip force detected by the detection unit; and a first guideline display control that, when the distal end force measurement unit exerts the distal end force on the subject in one direction, displays on the first chart a guideline of a direction in which the distal end force is exerted relative to the one direction.

8. The control unit a second monitor display control unit that causes a display unit to display a second chart that indicates, in real time, the shape of the fixing part and the tip force exertion position estimated by the tip force exertion position estimating unit with respect to the shape; and second guideline display control that, when the distal end force measurement unit exerts the distal end force on the subject in one direction, displays on the second chart a guideline of a position at which the distal end force is exerted in the one direction.

9. The control unit The muscle strength estimation device according to claim 1, further comprising a joint torque display control unit that controls the joint torque converted by the torque conversion unit so that maximum values ​​of the joint torque in each direction of knee extension, foot dorsiflexion, knee flexion, and foot plantar flexion are displayed on a display unit.

10. A muscle strength estimation method for estimating muscle strength of a subject's lower limbs by dividing the muscle strength into five muscle groups classified by function as muscle groups that have an effect on movement in a two-dimensional plane including a knee joint, an ankle joint, and a tip force exertion position where a tip force is exerted by the knee joint and the ankle joint, The muscle group is The anterior knee muscles, which act on the knee joint and are a combination of monoarticular and biarticular muscles on the front of the thigh, A posterior knee muscle group that acts on the knee joint in opposition to the anterior knee muscle group and is a combination of monoarticular muscles and biarticular muscles on the posterior side of the thigh; The anterior foot muscles are the anterior monoarticular muscles that act on the ankle joint; a posterior foot muscle group, which is a posterior monoarticular muscle acting on the ankle joint in an antagonistic manner to the anterior foot muscle group; a biarticular muscle group of the calves, which is a posterior biarticular muscle acting on the knee joint and the ankle joint without having an antagonist muscle; The muscle strength estimation method includes: a tip force measuring step of exerting the tip force on the subject in a plurality of directions within the two-dimensional plane and measuring the tip force exerted in each direction in at least two orthogonal axial directions within the two-dimensional plane; a tip force exertion position estimating step of estimating a tip force exertion position based on the tip force measured in the tip force measuring step and a moment generated around an axis perpendicular to the two-dimensional plane when the tip force is measured; a torque conversion step of converting each of the tip forces measured in the tip force measuring step into a joint torque based on the tip force exerting position estimated in the tip force exerting position estimating step; a drawing step of drawing, based on the joint torque converted by the torque conversion step, an output distribution of the joint torque in the shape of a hexagon, all of whose opposite sides have the same length, on a torque plane having the joint torque related to the knee joint as one axis and the joint torque related to the ankle joint as another axis perpendicular to the one axis; a muscle group torque estimation step of estimating the muscle group torque of the biarticular muscles of the calf based on one side of the hexagon of the output distribution drawn in the drawing step, estimating the muscle group torque of each of the anterior knee muscles and posterior knee muscles based on another side of the hexagon, and estimating the muscle group torque of each of the anterior foot muscles and posterior foot muscles based on the remaining side of the hexagon.

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