JP7142338B2 - Assist device control method and assist device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control method and assist device for an assist device, and more particularly to a control method and assist device suitable for controlling an assist device that assists human motion.

2. Description of the Related Art In recent years, an assist suit (assist device) that assists human motions such as medical training systems and rehabilitation, and human motions during work, as shown in Patent Document 1, is known.

JP-A-2005-230099

In the assist device, the assist force (assistance) is obtained by driving the actuator, but in the conventional control method of the actuator, when the person receives the assist force from the assist device, the assist force for the movement causes a sense of discomfort. Sometimes.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a control method and an assist device suitable for an assist device that assists human motion.

As a control method of the assist device for solving the above problems, according to the link mechanism provided so as to be able to bend and stretch according to the bending and stretching motion of the joint of the support target, and the operation state of the joint accompanying the motion of the support target, An actuator that applies a predetermined driving force to the rotation of the link mechanism, and an actuator that changes the viscosity and stiffness of the rotation of the link mechanism according to the motion state of the support target so that the assist force is applied to the joint of the support target. and control means for controlling the drive, wherein the control means sets the viscosity and stiffness according to increases and decreases in joint torque and angular acceleration in the motion of the support target when the motion of the support target is in the halt stage. and
According to this aspect, the actuator is controlled such that the viscosity and rigidity in the rotation of the link mechanism are changed according to the operation state of the support target, and the assist force is applied to the joint of the support target. Since a natural assisting force can be applied so as to follow the motion state, a comfortable assisting force can be provided to the support target. In addition, when the movement of the support target is in the stopping stage, by setting the viscosity and stiffness according to the increase and decrease of the torque and angular acceleration of the joints in the movement of the support target, It can provide a smooth assist force in a series of movements.
Further, as another aspect, by making the link mechanism attachable to a person, it is possible to provide an assisting force that is highly compatible with the person, and to assist the movement without causing discomfort.
In addition, as a configuration of an assist device for solving the above-mentioned problems, a link mechanism is provided so as to be able to bend and stretch according to the bending and stretching motion of the joint to be supported, and according to the motion state of the joint accompanying the motion of the support target , an actuator that applies a predetermined driving force to the rotation of the link mechanism; and a control means that controls the drive of the actuator. and provides an assisting force to the joint of the support target, wherein the control means converts the viscosity and stiffness into the torque and angular acceleration of the joint in the motion of the support target when the motion of the support target is in the stopping stage. It was configured to be set according to the increase or decrease.
According to this configuration, the actuator is controlled so that the viscosity and rigidity of the rotation of the link mechanism change according to the operation state of the support object, so that natural assistance follows the operation state of the support object. Since force can be imparted, it is possible to provide the support target with a comfortable assisting force. In addition, when the movement of the support target is in the stopping stage, by setting the viscosity and stiffness according to the increase and decrease of the torque and angular acceleration of the joints in the movement of the support target, It can provide a smooth assist force in a series of movements.

It is a figure which shows one Example of an assist apparatus. FIG. 4 is a diagram showing the configuration of an artificial muscle; 1A and 1B are an external perspective view and a cross-sectional view of an MR brake; FIG. FIG. 4 is a diagram showing a sampling operation for creating stiffness data and viscosity data in bending and stretching the knee; FIG. 4 is a model diagram for calculating knee joint torque; 2 is a graph showing the relationship between viscoelasticity and muscle tension during motion of an organism. FIG. 4 is a diagram showing stiffness data and viscosity data calculated based on sampling motion; 1 is a table summarizing the relationship of stiffness and viscosity to human motion stages. It is a figure which shows the process of assist operation|movement of a main controller. It is a figure which shows the result of an evaluation experiment.

Hereinafter, the present invention will be described in detail through embodiments of the invention, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are It includes configurations that are not necessarily essential to the solution and are selectively adopted.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an assist device that assists bending and stretching (bending and stretching) actions of legs and knees. The assisting device 1 shown in the figure is a so-called exoskeleton-type assisting device for assisting a person, and is an assisting robot for assisting the movement of the person. An exoskeleton-type device is a device that is attached to the human body without using the skeleton of the human body as a structural element in the operation of the assist device. Secondly, similar motions are performed independently to assist bending and stretching motions at the joints.
In the following embodiments, an example in which the assist device 1 is applied to the legs of a human body will be described. It can be applied to any part as long as it can take a stretched state.

The assist device 1 includes a drive mechanism 4 that applies an assist force (assistive force) to the thigh and lower leg, and a control mechanism 8 that controls the operation of the drive mechanism 4 .
Drive mechanism 4 generally includes frame 2 , artificial muscle 40 , wire 46 , MR brake 42 , pulley 44 and angle sensor 48 .

The frame 2 is composed of a thigh frame 20 attached to the thigh and a lower leg frame 22 attached to the lower leg. The thigh frame 20 is a rigid body extending from the base of the thigh to the knee joint along the outer lateral side of the thigh, and is fixed to the thigh by a fixing belt 3, 3 or the like. A mounting portion (not shown) for mounting the artificial muscle 40 is provided on the waist side of the thigh frame 20, and a mounting portion (not shown) for mounting the MR brake 42 is provided on the foot end side.

The lower leg frame 22 is a rigid body extending from the knee joint along the outer lateral side of the lower leg, and the ankle side is fixed to the lower leg by the fixing belt 3 or the like. The lumbar side of the lower leg frame 22 is provided with a mounting portion (not shown) for mounting the MR brake 42 , and is rotatably connected to the thigh frame 20 via the MR brake 42 .
In addition, the fixing belt 3 is made of, for example, a non-stretchable band, and has a hook-and-loop fastener functioning as a fixing means at the end in the extension direction, and a cushioning material (not shown) on one surface, so as to absorb the human body. The thigh frame 20 and the lower leg frame 22 are fixed to the human body while measuring .

FIG. 2 is a diagram showing the configuration of the artificial muscle 40. As shown in FIG. The artificial muscle 40 is an actuator that expands and contracts in the axial direction by supplying fluid. In this embodiment, an axial fiber-reinforced artificial muscle is applied to the artificial muscle 40 . The artificial muscle 40 is constructed by inserting a carbon fiber sheet 52 into a cylindrical body 50 made of natural latex rubber, for example. The carbon fiber sheet 52 has a plurality of carbon fibers 51 oriented along the axial direction of the cylindrical body 50 and restrains the extension of the cylindrical body 50 in the axial direction. Both ends of the cylindrical body 50 are closed by terminal members 53A and 53B. Thereby, an air chamber 56 is formed on the inner peripheral side of the cylindrical body 50 . One terminal member 53A is provided with an air flow port 55 that communicates with the air chamber 56, and is connected to a tube extending from an artificial muscle control device 80, which will be described later. A plurality of rings 54 are provided on the outer circumference of the cylindrical body 50 at equal intervals in the axial direction. When air, which is an example of a fluid, is supplied into the air chamber 56 of the artificial muscle 40 configured as described above, the cylindrical body 50 has a plurality of bumps partitioned by rings 54, as shown in FIG. 2(b). , and contract axially due to the restraining force of the carbon fiber sheet 52 . Also, by exhausting the air in the air chamber 56, as shown in FIG.

By using the artificial muscle 40 having such a configuration, it is possible to reduce the weight of the actuator and obtain a change in the assist force according to the standing-up motion. The artificial muscle 40 has a characteristic that the output characteristic (traction force) with respect to the contraction stroke is large at the beginning of contraction and gradually decreases toward the end of contraction. This characteristic corresponds exactly to the human characteristic that a large amount of force is required in the initial stage of a person's stand-up motion, and the required force gradually decreases as the stand-up motion progresses. It is preferable as a power source (driving force generating means) for obtaining force. In addition, by adjusting the pressure of the fluid supplied to the inside of the artificial muscle 40, it is possible to change the traction force. Its light weight can reduce the burden on the person when wearing it.
In the following description, the operating state of the artificial muscle 40 is indicated by axial extension and contraction.

As shown in FIG. 1, one end side of the artificial muscle 40 is fixed to an attachment portion on the waist side of the thigh frame 20 in parallel in the longitudinal direction of the person. Each end of the wire 46 is connected to the other end. That is, an antagonistic arrangement is made so that the traction force due to the contraction of one artificial muscle 40 acts on the other artificial muscle 40 .
The wire 46 is not limited to being made of metal, and may be made of synthetic fibers obtained by twisting organic fibers together, for example. Wire 46 is preferably of a material that has little stretch when tension is applied. In consideration of durability, metallic or non-metallic inorganic fibers are preferable, and from the viewpoint of weight, synthetic fibers obtained by twisting organic fibers are preferable.

3A and 3B are an external perspective view and a sectional view of the MR brake 42. FIG. The MR brake 42 is a device using a magneto-rheological fluid, and is configured to change the coefficient of friction at a response speed of about 10 ms by applying a magnetic field to the magneto-rheological fluid enclosed inside. The MR brake 42 is formed in a disc shape, and a core 64 is housed in a housing portion 62 provided in the center of the case 60 . The housing portion 62 is formed as a recess that is cylindrically recessed from one side surface. The core 64 includes a shaft portion 64A that is inserted into the housing portion 62, and a disk portion 64B that closes the opening of the housing portion 62. As shown in FIG. The core 64 is rotatably attached to the case 60 at the tip side of the shaft portion 64A. A coil 66 is provided on the outer circumference of the shaft portion 64A. Furthermore, a plurality of disc-shaped discs 68 are non-rotatably attached to the outer circumference of the coil 66 . A magnetic fluid 69 is enclosed in the space of the housing portion 62 of the case 60 housing the core 64 . In the MR brake 42, the core 64 rotates freely with respect to the case 60 when no voltage is applied to the coil 66, and the magnetic field generated by the coil 66 is applied to the magnetic fluid when the coil 66 is applied with voltage. By exerting an influence, braking the free rotation of the core 64, and applying the maximum allowable voltage to the coil 66, the magnetic fluid is solidified and the case 60 and the core 64 rotate together. As described above, the MR brake 42 has a high response speed of several tens of milliseconds, high output, and back drivability. The core 64 is attached as the fixed side, and the case 60 is attached as the rotating side.

As shown in FIG. 1, the core 64 side of the MR brake 42 is fixed to a mounting portion on the foot end side of the thigh frame 20, and the case 60 side is fixed to a mounting portion of the lower leg frame 22, respectively. Thereby, the thigh frame 20 and the crus frame 22 are rotatably connected via the MR brake 42, and form one link mechanism that bends and stretches according to the bending and stretching motion of the knee. A pulley 44 is fixed to the mounting portion of the lower leg frame 22 fixed to the MR brake 42 .

The pulley 44 is attached to the lower leg frame 22 so that the center of rotation is coaxial with the rotation axis of the MR brake 42 . A wire 46 connecting the antagonically arranged artificial muscles is stretched over the pulley 44 without slack. Therefore, by contracting one of the antagonistically arranged artificial muscles 40A and 40B more than the other, the wire 46 wound around the pulley 44 moves toward one of the artificial muscles 40A and 40B. A pulley 44 rotates passively. As the pulley 44 rotates, the crus frame 22 rotates together with the pulley 44 with respect to the thigh frame 20, so that the bending and stretching motion can be assisted.
The angle sensor 48 is angle detection means for detecting the rotation angle of the lower leg frame 22 with respect to the thigh frame 20 . The angle sensor 48 is provided so as to detect rotation of the lower leg frame 22 with respect to the thigh frame 20 . The angle sensor 48 is composed of, for example, an encoder or the like, and outputs the detected rotation angle to the control mechanism 8 .
In addition, the arrangement of the artificial muscle 40 is not limited to the above-described form, and it is sufficient that the pulley 44 is antagonically arranged such that the pulley 44 can be driven to rotate. Can be changed.

According to the drive mechanism 4 configured as described above, by supplying air only to one artificial muscle 40 or by supplying air having different pressures to one artificial muscle 40 and the other artificial muscle 40, the artificial muscle having a high pressure can be generated. The wire 46 moves to the 40 side and rotates the pulley 44 . Rotation of the pulley 44 causes the crus frame 22 to rotate with respect to the thigh frame 20 . That is, by providing a pressure difference in the air supplied between the artificial muscles 40 ; 40 , the rotation angle θ of the lower leg frame 22 with respect to the thigh frame 20 can be controlled. Further, even if the pressure difference is the same, the torque τ and the stiffness K of the lower leg frame 22 with respect to the thigh frame 20 can be controlled by setting the pressure supplied to each of the artificial muscles 40; 40 higher or lower. . That is, the antagonically arranged artificial muscles 40; 40 function as rigid force generating means.
Furthermore, by applying a voltage to the MR brake 42 when the pulley 44 rotates, it is possible to generate resistance to the rotation of the pulley 44 . That is, it is an actuator that generates a viscous force to drive the artificial muscles 40; 40, and functions as a viscous force imparting means.
In the following description, the artificial muscle 40 to which high-pressure air is supplied may be referred to as an agonist muscle, and the artificial muscle 40 to which low-pressure air is supplied may be referred to as an antagonist muscle.

As shown in FIG. 1 , the control mechanism 8 includes an artificial muscle control device 80 , an MR brake control device 82 , and a main control device 84 that controls the artificial muscle control device 80 and the MR brake control device 82 .
The artificial muscle controller 80 controls the pressure of the fluid within the artificial muscle 40;40 based on signals output from the main controller 84. FIG. Specifically, the pressure in the air chamber 56 of each artificial muscle 40A; 40B is adjusted to the pressure set for each artificial muscle 40A; control the air supply and discharge of the

The MR brake control device 82 is connected to the main control device 84 and outputs an adjusted voltage to the MR brakes 42 based on a signal input from the main control device 84 .

The main control unit 84 is a so-called computer, and includes arithmetic processing means such as a CPU provided as hardware resources, storage means such as ROM and RAM, and input means such as an operation panel and switches that are manually operated by the user. has an input interface to which is connected.

The storage means stores programs for controlling the driving of the artificial muscles 40A; 40B and the MR brake 42 and target value setting data. The arithmetic processing means functions as each means described later by executing each process according to the program stored in the storage means.
The command value setting data is data for setting command values for operating the artificial muscles 40A and 40B and the MR brake 42 in the assist operation, and is set for each assist target operation. The command value setting data described below is created for the purpose of assisting the bending and stretching motion of the knee joint. The target value setting data includes target stiffness data (simply referred to as stiffness data) and target viscosity data (simply referred to as viscosity data).

It is known that the viscoelasticity is proportional to the load torque of the motion as a knowledge about the viscoelasticity control of human joint motion. In particular, during the undulating phase of exercise (starting stage), the activity level of antagonistic muscles is reduced to reduce viscoelasticity, and when exercise is stopped (stopping stage), simultaneous activity of antagonistic and leading muscles reduces viscoelasticity. is known to increase Therefore, the target stiffness value and the target viscosity value in the assist motion are set to increase or decrease according to the increase or decrease in the torque of the joint in human motion. That is, the target stiffness value and the target viscosity value are set based on increases and decreases in joint torque in human motion. In this embodiment, it is set to be proportional to the torque τ and to increase only when motion is stopped. It should be noted that the stop of motion can be determined when the angular velocity and the angular acceleration of a joint have opposite signs in the motion of a human joint.

A method for creating stiffness data and viscosity data will be described below. FIG. 4 is a diagram showing a sampling operation for creating stiffness data and viscosity data in knee bending and stretching operations.
First, in creating stiffness data and viscosity data, as shown in FIG. Swing-up motion to extend the knee to the target position from the state where the knee is flexed at right angles, maintenance motion to maintain the knee-stretched state by swing-up, swing-down to return the knee to the state where the knee is flexed at right angles to the target position from the maintenance state A motion and a standby motion in which the knee is bent at a right angle are performed, and the actual angle of the knee joint accompanying the bending and stretching motion and the torque corresponding to the angle are acquired. The torque τ may be directly measured using a torque sensor or the like, or may be calculated by modeling the circumference of the knee joint as shown in FIG.

上記、式（１）乃至（４）におけるθ′は角速度、θ″は角加速度であり、人の関節の角度変化、即ち、角度センサ４８により検出される角度の変化により算出される。また、Ａ（トルクに対する重み係数）、Ｂ（粘弾性の振幅係数）、Ｋ_ｍ（装置の最低剛性（基底剛性））は、アシストする動作に応じて設定される定数であって、本例では、膝の屈伸動作に対応して設定される。なお、トルクに対する重み係数Ａには、０＜Ａ＜１の範囲の数値が設定される。 Next, stiffness data and viscosity data are created using the following equations together with the actual angle θ and torque τ obtained by the above-described actual bending and stretching motion of the knee.

In the above equations (1) to (4), θ′ is an angular velocity and θ″ is an angular acceleration, which are calculated from changes in angles of human joints, that is, changes in angles detected by the angle sensor 48. A (weighting coefficient for torque), B (amplitude coefficient of viscoelasticity), and K _m (minimum stiffness of device (base stiffness)) are constants set according to the motion to be assisted. It should be noted that the weighting factor A for the torque is set to a numerical value in the range of 0<A<1.

The above formula will be explained below. Equations (1) and (2) are equations for calculating the target stiffness value K, and equations (3) and (4) are equations for calculating the target viscosity value D.
Equation (2) calculates the target stiffness value when the angular velocity .theta.' and the angular acceleration .theta.'' indicating the motion state of the joint have the same sign, that is, when the stiffness need not be increased at the start of motion.
In equations (1) and (2), _τM is the maximum torque output in a certain exercise (here, bending and stretching of the knee), and τ is the torque during that exercise (referred to as actual torque). |τ/τ _M | is the maximum torque τ _M in a certain motion, and is obtained by normalizing the actual torque τ at that time, and indicates the ratio of the actual torque τ to the maximum torque τ _M . That is, the target stiffness value K calculated by Equation (2) is calculated as being proportional to the actual torque τ.

Further, when the angular velocity θ′ and the angular acceleration θ″ are of opposite signs, the target stiffness value _K is calculated by the equation (1). The maximum angular acceleration, θ″, is the angular acceleration (actual angular acceleration) during the movement.
|θ″/θ _M ^″ | is the maximum angular acceleration θ ^″ _M that occurs in a certain exercise (in this case, bending and stretching of the knee), and is the normalized actual angular acceleration θ″ at that time. It shows the ratio of the actual angular acceleration θ to ^″ _M ″. That is, the target stiffness value K calculated by Equation (1) is proportional to the torque τ and the actual angular acceleration θ″, and is calculated such that the target stiffness value K increases as the actual angular acceleration θ″ increases.

Similarly to the calculation of the target stiffness value K, the target viscosity value D calculated by the equations (3) and (4) also depends on the actual torque τ and the actual angular acceleration θ″.
According to the formulas (1) to (4), the relationship between the target stiffness K and the target viscosity D is such that the target stiffness D increases as the target stiffness K increases, and the target viscosity D increases as the target stiffness K decreases. related to becoming smaller. In addition, as described above, human viscoelasticity control is proportional to the load torque of exercise. The viscoelasticity is increased by the simultaneous action of the leading muscles, which matches the changes in the target stiffness value K and the target viscosity value D calculated by Equations (1) to (4).
Furthermore, focusing on the relationship between viscoelasticity and muscle tension during movement of living organisms, as shown in FIG. The points also match the changes in the target stiffness value K and the target viscosity value D calculated by the formulas (1) to (4).

FIG. 7 is a diagram showing stiffness data and viscosity data calculated by applying the actual angle and torque τ obtained by the sampling operation to formulas (1) to (4).
As shown in the figure, the stiffness data and the viscosity data continue smoothly along the time axis with respect to human motion, and do not change in the direction of the vertical axis (stiffness axis, viscosity axis) orthogonal to the time axis. , there is no discontinuous change that causes discomfort in the assist operation. Discontinuities refer to variations along the longitudinal axis of the stiffness and viscosity data. Since the stiffness data and the viscosity data are calculated based on the actual motion of the person as described above, they have a high affinity with the person and can provide the assist force without making the person feel uncomfortable. It becomes possible.

Based on the results shown in FIG. 7, the motions included in the series of bending and stretching motions of the knee are defined as "1. At the start of exercise,""2. At the end of exercise,""3. At the time of weakness (without exercise)," In order to provide assist force to the human movement so as not to hinder the human movement by classifying it into four movement phases (movement phases) when holding (the stage where a certain movement is maintained). , the relationship between the stiffness K and the viscosity D to be set in the control of the drive mechanism 4 can be generalized as shown in the table of FIG.
That is, the target stiffness value and the target viscosity value are decreased when the motion starts, and the target stiffness value and the target viscosity value are increased when the motion stops. Further, it is preferable to set the stiffness data and the target data so that the stiffness and viscosity are reduced when the body is not in motion and the target stiffness and viscosity are increased when the body is in motion.

FIG. 9 is a diagram showing the processing of the assist operation of the main controller 84. As shown in FIG.
The control processing of the artificial muscles 40A; 40B and the MR brake 42 by the main controller 84 according to the present embodiment is roughly divided into an interface hierarchy, a variable viscoelasticity hierarchy, and an FF controller hierarchy. The assist operation by the drive mechanism 4 is controlled by repeating the process from the viscoelastic hierarchy to the FF controller hierarchy.

The interface layer processes information input through the input means connected to the main controller 84, sets the start and type of assist operation based on the input information, and issues commands to the variable viscoelasticity layer. Output. That is, the interface layer functions as assist operation setting processing means. In the present embodiment, for convenience of explanation, it is assumed that the input means is a switch, and the necessity of the assist operation is input to the interface hierarchy by operating the switch. In this case, the assist operation command is output to the variable viscoelastic hierarchy when the switch operation is required, and the assist operation command is not output when the switch operation is not required. The input means is not limited to the switches described above, and may be information from a sensor provided in the drive mechanism as appropriate.

The variable viscoelasticity layer calculates a target angle, target torque, target stiffness, and target viscosity for causing a person to perform an assist operation by the drive mechanism 4 based on the information input from the interface layer, and calculates the calculated target angle , target torque, target stiffness and target viscosity as command values to the FF controller. That is, the variable viscoelastic layer operates as command value calculation means and command value output means.
A target angle is set based on an input value input from the angle sensor 48 . The target torque is, for example, set to a value corresponding to the target angle by referring to torque data that is created in advance corresponding to the assist operation and stored in the storage means. Further, the target stiffness K and the target viscosity D are set to values corresponding to the target angles by referring to the stiffness data and viscosity data stored in the storage means.

The FF controller layer determines a pressure value PA for driving the artificial muscles 40A and 40B based on command values (target angle θ, target torque τ, target stiffness K, and target viscosity D) input from the variable viscoelasticity layer. A voltage value E for driving the PB and the MR brake 42 is calculated, and the pressure value PA;PB is output to the artificial muscle control device 80 and the voltage value E is output to the MR brake 42 . That is, the FF controller hierarchy functions as actuator control means having a pressure control section and a voltage control section.
The setting of the pressure values PA; PB and the voltage value E in the FF controller hierarchy is executed by referring to the pressure value data and voltage value data stored in advance in the storage means. The pressure value data is a data map in advance for outputting pressure values corresponding to input command values such as target angle, target torque, and target stiffness. Also, the voltage value data is a data map for outputting a voltage value corresponding to the inputted target viscosity command value. The setting of the pressure values PA; PB and the voltage value E is configured as a program for calculating the pressure values PA; PB and the voltage value E using the target angle θ, the target torque τ, the target stiffness K and the target viscosity D as input values. can be

FIG. 10 is a diagram showing experimental results for evaluating the operation of the assist device 1 of this embodiment. More specifically, FIG. 10(a) is a graph showing changes in myoelectric potential without assistance and changes in myoelectric potential when the viscoelasticity is fixed and an assist operation is performed. FIG. 10(b) is a graph showing a change in myoelectric potential without assistance and a change in myoelectric potential when an assist operation is performed by changing viscoelasticity according to the method of the present embodiment. In addition, in the evaluation, the bending and stretching motion of the knee was used.
As shown in FIG. 10(a), when the viscoelasticity is a fixed value, the peak of myoelectric potential shifts as indicated by the arrows in the figure and unnecessary peaks surrounded by circles are observed. It was a result that can not be said to be amplifying (assisting).
On the other hand, as shown in FIG. 10(b), when the viscoelasticity is changed by the method of the present embodiment, the viscoelasticity changes based on human motion, so the myoelectric potential has a similar shape to that in the case of no assist. , resulting in amplification of human muscle movements. That is, the assist force can be applied without making the person receiving the assist feel uncomfortable.

As described above, in the present embodiment, the artificial muscles 40; 40 are arranged antagonistically so as to imitate the viscoelastic characteristics of human muscles, and the MR brake 42 applies braking to the driving of the artificial muscles 40; Thus, by controlling the operation of the artificial muscles 40 and 40 and the MR brake 42, it is possible to provide assistance to the wearer's movements without discomfort.

In the present embodiment, the actuator control method has been described using an assist device that assists the bending and stretching of the knee joints of the legs. can also be applied to

Further, in the above embodiment, in order to control the driving of the artificial muscles 40; 40 and the MR brake 42, the stiffness data and the viscosity data are calculated in advance by the formulas (1) to (4) based on the sampling operation, Formulas (1) to (4) are stored in the storage means as a program, and based on the angle and angle change detected by the angle sensor 48 when the person actually moves, The target stiffness value and the target viscosity value may be calculated sequentially.

In addition, according to this control method, the artificial muscle 40 and the MR brake 42 can be controlled only by the actual angle of the joint detected by the angle sensor 48 attached to the orthosis, which reduces the weight of the orthosis. In addition, complicated control can be made unnecessary.

In addition, the control method described above is not limited to an exoskeleton-type assist device that assists human motion, but can also be applied to control of an endoskeleton-type assist device, or control of a humanoid robot that operates according to a program. It is possible to make these movements similar to human movements.

The configurations of the drive mechanism 4 and the control mechanism 8 described in the above embodiments are not limited to the above embodiments, and may be changed as appropriate.
For example, in the drive mechanism 4 described above, an axial fiber type actuator is used as the actuator that generates the assist force, but the type of the actuator is not limited to this, and other actuators such as motor drives and air cylinders can be used. It may be an actuator. It is preferable to select the above-described artificial muscle that can reduce the weight in consideration of wearing on the human body.

Also, although the pulley is attached to the frame through the MR brake, the MR brake and the pulley may be integrated. Also, although the MR brake is used as the actuator for expressing the viscosity, the ER brake may be used instead of the MR brake.

In the above embodiment, in setting the target stiffness value and the target viscosity value in the control of the drive mechanism 4, the target stiffness value and the target viscosity value are increased or decreased in proportion to the torque τ or the torque τ and the angular acceleration θ ^″ . However, it is not limited to the proportionality (linear function), and the relationship between the torque τ, or the torque τ and the angular acceleration θ ^″ , and the change in the target stiffness value and the target viscosity value can be appropriately set according to the human action. Good luck. For example, by using a quadratic function or any function of higher order, the target stiffness value and the target stiffness value can be adjusted according to the increase or decrease of the torque τ or the torque τ and the angular acceleration θ ^″ so as not to oppose the human motion in the assist operation. It is sufficient if it is set so that the viscosity value increases or decreases.

In addition, although the drive mechanism 4 is mounted on the human body, for example, a part of the drive mechanism such as a link mechanism or an actuator that bends and stretches according to the bending and stretching motion of the human joint is provided at a position away from the human body, and the link mechanism You may make it interpose the transmission means which transmits bending-stretching operation|movement of this to a person.

Also, the support target is not limited to humans, and may be animals other than humans, broken-down robots, or the like.

1 assist device, 2 frame, 4 drive mechanism, 8 control mechanism,
40 artificial muscle (actuator), 42 MR brake (actuator).

Claims (4)

a link mechanism that can bend and stretch according to the bending and stretching motion of the joint to be supported;
an actuator that applies a predetermined driving force to the rotation of the link mechanism according to the motion state of the joint accompanying the motion of the support target;
a control means for controlling the driving of the actuator so as to change the viscosity and rigidity in the rotation of the link mechanism according to the motion state of the support target, and apply an assist force to the joint of the support target ;
wherein the control means sets the viscosity and the stiffness in accordance with increases and decreases in joint torque and angular acceleration in the motion of the assisted object when the motion of the assisted object is in a halt stage. control method. 2. A control method for an assist device according to claim 1, wherein said link mechanism is configured to be wearable on a person. a link mechanism that can bend and stretch according to the bending and stretching motion of the joint to be supported;
an actuator that applies a predetermined driving force to the rotation of the link mechanism according to the motion state of the joint accompanying the motion of the support target;
a control means for controlling the driving of the actuator;
with
The assist device, wherein the control means changes the viscosity and rigidity in the rotation of the link mechanism according to the motion state of the support target, and applies an assist force to the joint of the support target,
The assist device, wherein the control means sets the viscosity and the stiffness in accordance with increases and decreases in joint torque and angular acceleration in the motion of the support target when the motion of the support target is in a halt stage. 4. The assist device according to claim 3, wherein said link mechanism is configured to be wearable on a person.

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