JP2004105609A - Drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive device such as a knee joint training device for flexibly varying a preset trajectory according to resistance force from a patient so as to train by a human hand. <P>SOLUTION: A constitution of this drive device is provided with a holding member arranged so as to hold a driven part and moving along the movement of the driven part, a rigidity variable mechanism for imparting variable rigidity to the holding member and a drive mechanism for allowing the moving of a constant trajectory existing in the driven part by changing a rigidity center position made by the rigidity variable mechanism. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving device, and more particularly to a driving device applicable to a medical device and a robot (humanoid) for training a knee joint and other joints. Hereinafter, the drive device of the present invention will be described in relation to a knee joint training device, but the present invention is not limited to a knee joint training device.
[0002]
[Prior art]
After operating on the patient's knee, the knee is fixed and immobilized for a period of time for post-operative recovery of the knee. As a result, the range of movement of the knee is reduced, and rehabilitation is required. Conventionally, the use of CPM (continuous passive exercise) as a rehabilitation training device has been proposed in, for example, JP-A-06-105877, JP-A-08-196585, and JP-A-11-192273. I have.
[Patent Document 1] JP-A-06-105877 [Patent Document 2] JP-A-08-196585 [Patent Document 3] JP-A-11-192273 [0003]
[Problems to be solved by the invention]
In the above-described conventional CPM, the lower leg is repeatedly rotated about the knee with respect to the thigh. However, unlike training by human hands, the set trajectory is set. Could not be flexibly varied according to the resistance from the patient.
[0004]
Therefore, an object of the present invention is to provide a driving device such as a knee joint training device capable of flexibly changing a set trajectory in accordance with resistance from a patient so that training is performed by a human hand. .
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a holding member that is arranged to hold a driven portion, moves along the movement of the driven portion, and a stiffness variable mechanism that gives the holding member a variable stiffness. And a drive mechanism that changes the center position of the rigidity created by the variable rigidity mechanism and causes the driven section to move along a certain orbit.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram for explaining a knee joint training apparatus using the variable stiffness mechanism of the present invention. FIG. 2 is a diagram for explaining the principle of the variable stiffness mechanism of the present invention. FIG. 3 is a diagram for explaining the operation characteristics of the nonlinear spring of the present invention. FIG. 4 is a diagram for explaining secondary characteristics of the nonlinear spring. FIG. 5 is a diagram for explaining rigidity variation by two secondary characteristic springs. FIG. 6 is a graph for explaining stiffness variation by two nonlinear springs. FIG. 7 is a diagram for explaining a mechanism for changing the center position of rigidity. FIG. 8 is a diagram showing a configuration of a conical spring as an example of the secondary characteristic spring. FIG. 9 is a graph showing characteristics of a conical spring.
[0007]
First, the principle of the variable stiffness mechanism of the present invention will be described with reference to FIG. In short, the variable rigidity mechanism 10 obtains a member 12 having a linear spring characteristic of variable rigidity by combining two nonlinear springs 11 having two quadratic (square) characteristics.
[0008]
The member 12 at the antagonistic point is made of, for example, a slider, and non-linear springs 11 are arranged at both ends in the direction in which the member moves so that forces are applied in opposite directions. The other end of the non-linear spring has a member for compressing the spring, and the distance of the member 13 for compressing the spring can be changed by the servomotor 14.
[0009]
In the variable stiffness mechanism configured as described above, when the member 13 for compressing the spring is moved by each servomotor 14, the spring 11 is compressed. Since the two springs 11 are connected by the member 12 at the antagonistic point, the member 12 at the antagonistic point moves and stops until the mutual forces are opposed. This predetermined position will depend on the stiffness of the linear spring characteristic at the antagonistic point.
[0010]
Next, with reference to FIGS. 3 to 6, how the antagonistic point member 12 is given a linear spring characteristic will be described. FIG. 3 shows an unequal pitch coil spring 11 having a non-linear spring characteristic (particularly a secondary spring characteristic). That is, the coil pitch is gradually changed so as to correspond to the secondary spring characteristic. The unequal-pitch coil spring may be a conical unequal-pitch coil spring in which the coil diameter is gradually reduced as well as the one having a coil portion having the same diameter. 8 and 9 show, by way of example, the structure of a conical spring with secondary characteristics and the characteristics of a conical spring with secondary characteristics. Japanese Unexamined Patent Application Publication No. 2000-337415 discloses a non-linear deformed coil. Since a spring having a secondary characteristic can be manufactured from the non-linear deformed coil, it can be used as a spring having a secondary characteristic used in the present invention.
[0011]
When the spring having the secondary spring characteristic is compressed, the spring force exhibits the secondary characteristic with respect to the compression amount (movement position) as shown in FIG.
[0012]
Now, it is assumed that two springs having secondary characteristics as shown in FIG. 4 are arranged as shown in FIG. Here, assuming that the free length of the spring is x ₀ (m), the relationship between the length x (m) of the nonlinear spring and the force f (N) is as follows.
f = k (x−x ₀ ) ² (1)
It can be expressed as. Here, k is a constant proportional to the square and the unit is N / m ² . Here, assuming that the two springs antagonize at the position shown in FIG. 5, assuming that the distance between the support points is 21 (m) and the distance from the center is x _c (m), the compression force f generated in each spring. ₁ , f ₂ is
f ₁ = k (l + x _c −x ₀ ) (2)
_{f 2 = k (l-x} c -x 0) (3)
Next, the resultant force _{f 12} is _{f 12 = 4k (l-x} 0) x c
Next, the characteristics of a linear spring to 4k a _{(l-x 0)} proportionality constant is obtained.
In the calculation of the above formula, x for simplicity, are omitted range conditions such as x _c.
[0013]
As a result, as shown in the graph of FIG.
[0014]
Next, a knee joint training apparatus using the variable stiffness mechanism of the present invention will be described with reference to FIG. A variable stiffness mechanism 10 is provided, the details of which are already described with reference to FIG.
[0015]
The knee joint training apparatus 100 includes, in addition to the variable stiffness mechanism 10, a drive mechanism 20 that changes the center position of the stiffness created by the variable stiffness mechanism and causes the leg 50 to move in a certain orbit. The drive mechanism 20 includes, for example, a slider 21, a ball screw 22, and a servomotor 23, as shown in FIG. By moving the stiffness variable climate 10 on the slider by the servo motor, the center position of the stiffness can be changed.
[0016]
The motors used in the variable stiffness mechanism 10 and the drive mechanism 20 that changes the center position of the stiffness are controlled by a trajectory / rigidity characteristic input device 40 including a motor controller, and generate a trajectory and a stiffness used for training.
[0017]
Further, the knee joint training apparatus 100 includes a leg holding member 30 for transmitting the movement and the force generated by the rigidity variable mechanism 10 and the rigidity-centered driving mechanism 20 to the leg 50 of the patient. The leg holding member 30 is arranged to hold the leg 50 of the patient, and moves along with the movement of the leg. Further, the leg holding member 30 is connected to the member 12 at the antagonistic point of the variable stiffness mechanism 10. This is performed by 20 servomotors 23. By adjusting the posture and rigidity in this way, rehabilitation training can be received under optimal conditions for the patient.
[0018]
Although the driving device of the present invention has been described by taking the knee joint training device as an example, the present invention can be applied not only to the knee joint but also to other joints, and can also be applied to a robot (humanoid). It is.
[0019]
【The invention's effect】
As described above, according to the present invention, for example, a driving device such as a knee joint training device capable of flexibly changing a set trajectory in accordance with the resistance force from a patient, such as training with human hands Is obtained.
[0020]
In addition, the following effects can be obtained.
(1) Softness can be achieved even when the speed of the servo motor is low. Also, the torque can be relatively small.
(2) Softness can be maintained even when the power supply stops.
(3) No force sensor is required. In addition, it responds even if a force is applied to a place where it cannot be sensed by the force sensor.
[Brief description of the drawings]
FIG. 1 is a configuration diagram for explaining a knee joint training apparatus using a variable stiffness mechanism of the present invention.
FIG. 2 is a diagram for explaining the principle of the variable stiffness mechanism of the present invention.
FIG. 3 is a diagram for explaining the operation characteristics of the nonlinear spring of the present invention.
FIG. 4 is a diagram for explaining secondary characteristics of the non-linear spring.
FIG. 5 is a diagram for explaining rigidity variation by two secondary characteristic springs.
FIG. 6 is a graph for explaining stiffness variation by two secondary characteristic springs.
FIG. 7 is a diagram for explaining a mechanism for changing a center position of rigidity.
FIG. 8 is a diagram showing a configuration of a conical spring as an example of a secondary characteristic spring.
FIG. 9 is a graph showing characteristics of a conical spring.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Variable stiffness mechanism 11 Nonlinear spring 12 Member of antagonistic point 13 Member for compressing spring 14 Servo motor 20 for compressing spring Drive mechanism 21 for changing center position of rigidity Slider 22 Ball screw 23 Servo for changing center position of rigidity Motor 30 Leg holding member 40 A track including a motor controller. Stiffness characteristic input device 50 Patient's leg 100 Knee joint training device 20 Lower leg holding member

Claims (3)

A holding member that is arranged to hold the driven part, and that moves along the movement of the driven part;
A variable stiffness mechanism that provides variable stiffness to the holding member;
A drive mechanism that changes the center position of the rigidity created by the rigidity variable mechanism and moves the driven section along a certain orbit;
A driving device, comprising: The drive device according to claim 1, wherein the rigidity is linear, and the rigidity variable mechanism is configured by a combination of two secondary characteristic springs. The drive device according to claim 1, wherein the variable stiffness mechanism includes:
A first spring having secondary characteristics;
A second spring having secondary characteristics;
A wire connecting the ends of the first and second springs;
Two servomotors for controlling the compression of the first and second springs and their operating position;
Has,
The stiffness is determined based on the antagonism of the first spring and the second spring to which the acting force is applied by the servomotor, and the center of the stiffness is determined by moving a point of antagonism.
A drive device characterized by the above-mentioned.

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