JPH05116088A - Posture control method for movable body by compliance mechanism - Google Patents

Abstract

PURPOSE:To restrain a moment acting on a movable body by acceleration/ deceleration in the movement of a compliance mechanism. CONSTITUTION:An orthogonally acrossing frame of reference which can represent restitutive force acting on a movable body 1 from a compliance mechanism E by only a displacement in the direction along the axis of coordinates and the angle displacement by the rotation around each axis of coordinates is arranged. The original point of this orthogonally acrossing frame of reference is represented by an elastic center S. When the compliance mechanism E is moved, the restitutive force acting on the movable body 1 from the compliance mechanism E is adjusted so that the elastic center S can be coincident with the gravity center of the movable body 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a posture control method for a movable body by means of a compliance mechanism in which the posture of the movable body is controlled by adjusting the restoring force and the damping force acting on the movable body from the compliance mechanism. It is about.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 14, a compliance mechanism E is provided at the tip of an arm C of a robot, and a movable body 1 having a chuck 1c for holding a work B is supported by the compliance mechanism E. It is considered that the posture of the movable body 1 is controlled by adjusting the restoring force and the damping force acting on the movable body 1 by the compliance mechanism E. That is, by controlling the attitude of the movable body 1, fine adjustment of the position of the work B in a precision assembly device or the like is performed.

By the way, in the assembling apparatus using the compliance mechanism E, it is necessary to move the compliance mechanism E to a position where the work B is mounted while the work B is held by the chuck 1c. Since the compliance mechanism E supports the movable body 1 by applying a restoring force and a damping force to the movable body 1, when the compliance mechanism E is moved by acceleration,
The movable body 1 moves with respect to the compliance mechanism E. In particular, if the compliance mechanism E is moved at high speed for the purpose of shortening the assembly time,
Since the compliance mechanism E is rapidly accelerated and decelerated rapidly, the acceleration acting on the movable body 1 is increased, so that the force for moving the movable body 1 is increased.

For example, considering the case of moving the compliance mechanism E to the right in FIG. 15, during acceleration, the movable body 1 is displaced to the left of the center of the compliance mechanism E as shown in FIG. The moment acts on the movable body 1 and the movable body 1 tilts. During deceleration, the movable body 1 is displaced to the right of the center of the compliance mechanism E as shown in FIG. 15B, and a moment acts on the movable body 1 to tilt the movable body 1. When the movable body 1 moves with respect to the compliance mechanism E by the movement of the compliance mechanism E as described above, the movable body 1 easily collides with the compliance mechanism E, which leads to damage to the compliance mechanism E and the movable body 1. There is a problem that the component B may be dropped. Further, even if the movable body 1 does not collide with the compliance mechanism E, if the movable body 1 suddenly changes from a state of acceleration or deceleration to a state of movement at a constant speed or suddenly stops, then it moves as shown in FIG. The body 1 vibrates and the settling time becomes long, which may cause a problem that it takes a long time to position the component B. In short, if the compliance mechanism E is moved at a high speed in order to shorten the assembly time, the device may be damaged, or the settling time becomes long and the assembly time cannot be shortened.

In order to solve such a problem, the compliance mechanism E is provided with a positioning piston, and the work B
It has been considered that the movable body 1 is mechanically fixed to the compliance mechanism E by a positioning piston during the movement period from the time when the user grips to the desired position (Japanese Patent Laid-Open No. 62-68231).

[0006]

However, in the above structure, it is necessary to provide the compliance mechanism E with a mechanical device for fixing the movable body 1 only during the movement period.
There is a problem that the structure becomes complicated and the whole becomes large. Further, when the positioning piston is brought into contact with the movable body 1 in order to fix the position of the movable body 1 with respect to the compliance mechanism E, an impact force may act on the movable body 1, and the work B with respect to the chuck 1c. The position may be misaligned or dropped.

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and suppresses a moment acting on a movable body by acceleration and deceleration when the compliance mechanism moves, thereby making it difficult for the movable body to collide with the compliance mechanism. An object of the present invention is to provide a posture control method for a movable body using a compliance mechanism, which enables the compliance mechanism to move faster than before.

[0008]

According to the present invention, in order to achieve the above object, the posture of the movable body is adjusted by adjusting the restoring force and the damping force applied by the compliance mechanism to the movable body supported by the compliance mechanism. In the attitude control method of the movable body by the compliance mechanism for controlling the, it is set so that the restoring force acting on the movable body can be expressed only by the displacement due to the translation along the coordinate axis and the angular displacement due to the rotation around each coordinate axis. With the position of the origin of the orthogonal coordinate system as the elastic center, the restoring force acting on the movable body by the compliance mechanism is adjusted so that the elastic center coincides with the center of gravity of the movable body when the compliance mechanism moves.

[0009]

If the elastic center is defined as described above, the external force acting on the movable body is equal to the total external force acting on the center of gravity of the movable body, and the moment around the elastic center acts on the center of gravity. It can be considered that it is caused by an external force, so by adjusting the restoring force that acts on the movable body from the compliance mechanism by the above method, if the elastic center of the movable body is aligned with the center of gravity when the compliance mechanism moves, It is possible to prevent the moment from acting on the body. That is, when the compliance mechanism moves, the movable body does not perform rotational movement but only performs translational movement in the movement direction of the compliance mechanism. Is less likely to collide with.

[0010]

EXAMPLE In this example, the compliance mechanism E having the structure shown in FIGS. 8 to 11 is used. This compliance mechanism E includes three electromagnets 2 ₁ , 2 ₂ and 2 ₃ that surround a circular plate 1a made of a magnetic material provided on the movable body 1 so as to face a peripheral portion of the lower surface of the circular plate 1a. A magnetic bearing for the movable body 1 is formed by arranging the electromagnets 6 at equal intervals along the direction, and by arranging one electromagnet 6 so as to face the central portion of the surface of the disc 1a. Three linear actuators 3 ₁ , around the upper surface of the
It has a configuration in which 3 ₂ and 3 ₃ are joined at equal intervals along the circumferential direction. Here, the disk 1a of the electromagnets 2 ₁ , 2 ₂ , 2 ₃
The surface opposite to is located on the same plane.
It is defined as a plane parallel to the plane.

Linear actuators 3 ₁ , 3 ₂ , 3
_As shown in FIGS. 12 and 13, ₃ is a permanent magnet 3a which is formed in a substantially E shape and has leg pieces on both sides and a leg piece at the center magnetized with different polarities, and a leg at the center of the permanent magnet 3a. The moving coil 3b has a rectangular tube shape and is inserted into the piece. Therefore, when a direct current is applied to the movable coil 3b, a Lorentz force corresponding to the magnitude of the current acts on the movable coil 3b, so that the movable coil 3b reciprocates in the direction along the center leg of the permanent magnet 3. is there. This linear actuator 3 ₁ , 3
₂ and 3 ₃ are arranged such that the plane including all the leg pieces of the permanent magnet 3a is parallel to the XY plane, and the leg pieces are in the same direction along the circumferential direction. The movable coil 3b of each linear actuator 3 ₁ , 3 ₂ , 3 ₃ is mechanically coupled to the disc 1a of the movable body 1 and moves relative to the permanent magnet 3a in a plane orthogonal to the leg piece. It is arranged apart from the permanent magnet 3a so as to be able to. Therefore, the movable body 1 can be translated or rotated in a plane parallel to the XY plane by controlling the magnitude of the current supplied to the movable coil 3b of each linear actuator 3 ₁ , 3 ₂ , 3 _3. You can do it.

On the other hand, since the electromagnets 2 ₁ , 2 ₂ and 2 ₃ exert a force on the disc 1a in a direction orthogonal to the XY plane, that is, in the Z-axis direction, the electromagnets 2 ₁ and 2 2 ₂ ,
By controlling the magnitude of current supplied to 2 _3, with translating the movable member 1 in the Z-axis direction, the disc 1a can be tilted in an arbitrary direction with respect to the XY plane. As described above, the posture control in which the movable body 1 is supported by magnetic force in a non-contact manner and which has three degrees of freedom in translation and rotation can be performed. The posture of the movable body 1 is 6
The position sensors 4 ₁ , 4 ₂ , 4 ₃ , 4 ₄ , 4 ₅ , 4 ₆ detect the position sensors. Each position sensor 4 ₁ , 4 ₂ , 4 ₃ ,
For example, magnetic types are used as 4 ₄ , 4 ₅ and 4 ₆ . The three position sensors 4 ₁ , 4 ₂ and 4 ₃ are the disc 1a.
Since they are arranged so as to face the peripheral portion of the upper surface of the movable body 1 and the displacement in the Z-axis direction is detected, the translation of the movable body 1 in the Z-axis direction and the inclination with respect to the XY plane can be detected. The remaining three position sensors 4 ₄ , 4 ₅ and 4 ₆ are arranged so as to face the peripheral surface of the disc 1a or the projecting piece provided on the peripheral face of the disc 1a as shown in FIG. Therefore, translation and rotation in the XY plane can be detected.

Each position sensor 4 ₁ , 4 ₂ , 4 ₃ , 4 ₄ , 4
_5, the position information output from the 4 _6, the interface 7
A current corresponding to a control signal, which is taken into the microcomputer 5 via the and is output from the microcomputer 5 so as to control the movable body 1 in a desired posture, is output from the interface 7 and amplified by the amplifier 8.
The electromagnets 2 ₁ , 2 ₂ , 2 ₃ and the movable coils 3 b of the linear actuators 3, ₁ , 3 ₂ , 3 ₃ are energized. The amplifier 8 is connected to a driving power source 9 for ensuring a required current to be applied to the movable coils 3b of the electromagnets 2 ₁ , 2 ₂ and 2 ₃ and the linear actuators 3 ₁ , 3 ₂ and 3 ₃ . As such a compliance mechanism E, an air bearing is used instead of the magnetic bearings of the electromagnets 2 ₁ , 2 ₂ , 2 ₃ , and 6, a coil spring is used instead of the electromagnet 6, and a linear actuator 3 is used. _It is possible to use a flat coil fixed to the disc 1a in the magnetic field of the electromagnets 2 ₁ , 2 ₂ and 2 ₃ instead of ₁ , 3 ₂ and 3 _3. There is no change in what you can do.

As shown in FIG. 8, the compliance mechanism E is housed in an outer frame 10 provided at the tip of an arm C of the robot, and has a peg 1b projecting from the center of the lower surface of the disk 1a of the movable body 1. A chuck 1c for holding the work B is provided therethrough. To the outer frame 10, the electromagnets 2 ₁ , 2 ₂ , 2 ₃ , 6 of the compliance mechanism E and the permanent magnets _{3 a} of the linear actuators 3, ₁ , 3 ₂ , 3 ₃ are fixed. By using the assembling apparatus thus configured, the work B can be aligned and inserted into the hole a of the directional component A.

By the way, if the assembling apparatus using the compliance mechanism E is simplified, a model as shown in FIG. 1 can be considered. That is, as shown in FIG. 1A, since the movable body 1 is supported by the compliance mechanism E in a floating state, and the work B held by the chuck 1c provided on the movable body 1 is inserted into the hole a of the component A. Therefore, the movable body 1 has restoring elements k ₁ and k for applying restoring force to the compliance mechanism E as shown in FIG.
It can be considered that they are coupled via ₂ , k ₃ and k ₄ and damping elements c ₁ , c ₂ , c ₃ and c ₄ that exert a damping force as shown in FIG. The compliance mechanism E uses the restoring force of the restoring elements k ₁ , k ₂ , k ₃ , k ₄ .
And the damping force by the damping elements c ₁ , c ₂ , c ₃ , c ₄ can be adjusted.

By the way, since the movable body 1 is held by the compliance mechanism E described above, the motion of the movable body 1 can be described by using the equation of motion of the system of 6 degrees of freedom. That is, when considering that the force is constrained to move only on one plane for simplification, the restoring force is as shown in FIG.
As shown in FIG. 2A, the force F (= −k · Δx, k is a constant) acting on the basis of the displacement Δx due to the translational movement of the movable body 1, and the force around the origin of the movable body 1 as shown in FIG. 2B. Moment M (= -k) acting based on angular displacement Δθ due to rotational movement
r · Δθ and kr are constants. Similarly, as shown in FIG. 3A, the damping force is a force F (= −c · Δx ′, where c is a constant, Δ, which acts based on the time change Δx ′ of the displacement Δx.
x'is velocity) and the moment M (= -cr) acting based on the time change Δθ 'of the angular displacement Δθ as shown in FIG. 3 (b).
・ Δθ 'and cr are constants and Δθ' is angular velocity). Further, since the restoring force and the damping force have 6 degrees of freedom, the restoring force is represented by a vector {Fs} having 6 elements, and the displacement Δx and the angular displacement Δθ each have 3 elements, that is, a total of 6 elements. Considering the vector {r}, the restoring force {F
s} can be expressed by the following equation.

{Fs} = [K] {r} Here, [K] is a matrix having 6 × 6 elements and is called a stiffness matrix. On the other hand, if the damping force is also expressed in the same format, the damping force {Fd} is {Fd} = [C] {r '}. However,-{r '} is a vector obtained by time-differentiating each element of the displacement vector {r}, and [C] is a matrix having 6 × 6 elements, which is called a damping matrix (damping matrix).

The stiffness matrix [K] and the damping matrix [C] are symmetric matrices, and can be diagonalized by appropriate coordinate transformation. When such an orthogonal coordinate system is set, the restoring force {Fs} can be expressed only on the basis of the displacement in the direction along each coordinate axis and the angular displacement around each coordinate axis, and the damping force {Fd} can be expressed on each coordinate axis. It can be expressed based on only the temporal change of the displacement along the direction and the angular displacement around each coordinate axis. Such a Cartesian coordinate system can set the restoring force and the damping force independently of each other.
As shown in, the origin of the orthogonal coordinate system set for the restoring force is called the elastic center S, and the origin of the coordinate system set for the damping force is called the damping center D.

As described above, if the elastic center S and the damping center D are defined, when the action line of the external force passes through the elastic center S, the movable body 1 does not tilt but translates on the action line of the external force, and When the line of action does not pass through the elastic center S, the movable body 1 rotates around the elastic center S. Further, when the line of action of the external force passes through the damping center D when the external force changes with time, the movable body 1 translates on the line of action of the external force without tilting, and the line of action of the external force does not pass through the damping center D. The movable body 1 rotates around the damping center D. That is, when the acceleration during the movement of the compliance mechanism E is constant, if the elastic center S coincides with the center of gravity G of the movable body 1, the movable body 1 does not tilt but only translates in the moving direction of the compliance mechanism E. Will be done. Further, when the acceleration during the movement of the compliance mechanism E changes, if the damping center D is aligned with the center of gravity G of the movable body 1, the movable body 1 does not incline and only translates in the moving direction of the compliance mechanism E. Will be done. Considering now the case where the elastic center S coincides with the center of gravity G of the movable body 1, the compliance mechanism E is moving rightward in FIG. 5, and the acceleration at the time of movement is constant. Suppose When the compliance mechanism E accelerates, the movable body 1 is displaced leftward with respect to the center line L of the compliance mechanism E as shown in FIG. 5A, but at this time, no moment acts on the movable body 1. Therefore, even if a relatively large external force acts, the movable body 1
Does not collide with the compliance mechanism E, so that the margin becomes large as compared with the case where a moment acts. As a result, the compliance mechanism E can be moved at a higher speed than when a moment acts. Similarly, when the compliance mechanism E slows down, the movable body 1 is displaced to the right with respect to the center line L of the compliance mechanism E as shown in FIG. 5B, but no moment acts. Further, even if the movable body 1 does not collide with the compliance mechanism E due to sudden stop, the movable body 1 may vibrate as shown in FIG. Since the vibration due to the component does not occur, the settling time can be made relatively short.

Next, the electromagnet 2 of the compliance mechanism E
₁ , 2 ₂ , 2 ₃ , linear actuator 3 ₁ , 3 ₂ , 3
By controlling the _third current supplied to the movable coil 3b, illustrating a method of matching the center of gravity of the movable body 1 in the elastic center S. First, consider the condition in which the movable body 1 is stationary with respect to the compliance mechanism E. That is, the static balance condition of the movable body 1 can be expressed by the following equation of motion.

{F} + [C] {r '} + [K] {r} = 0, where [C] is a damping matrix, [K] is a stiffness matrix, and {r} is a displacement vector. , {F}
Is the vector of the external force acting on the movable body 1, and {r '} is the time derivative of {r}. Among the above equations of motion, what can be controlled by the compliance mechanism E is
These are the elements of the attenuation matrix [C] and the stiffness matrix [K]. On the other hand, compliance mechanism E
The position sensor 4 _1, 4 _2, 4 _{3, 4} 4, 4 _5, because they comprise a 4 _6, the position sensors 4 _1, 4 _2, 4 _{3, 4} 4,
If the outputs of 4 ₅ and 4 ₆ are represented by a vector of 6 components as {dx}, the displacement vector {r} can be represented as follows.

{R} = [S] {dx}, where [S] is a matrix determined by the structure of the compliance mechanism E, and the position sensors 4 ₁ , 4 ₂ , 4
It is a coordinate conversion matrix that converts the detected values of ₃ , 4 ₄ , 4 ₅ , and 4 ₆ into coordinate values of a coordinate system having the elastic center S as the origin. If the electromagnetic force acting on the movable body 1 by the electromagnets 2 ₁ , 2 ₂ , 2 ₃ and the linear actuators 3, ₁ , 3 ₂ , 3 ₃ is represented by a six-component electromagnetic force vector {fe}, The electromagnetic force vector {fe} is set to the elastic center S by the formula
Can be converted into a force {f} acting on.

{F} = [E] {fe} ... [E] is a conversion matrix determined by the structure of the compliance mechanism E. Electromagnetic force vector {fe}
By using a current vector {ie} whose elements are the respective currents flowing to the moving coils 3b of the electromagnets 2 ₁ , 2 ₂ , 2 ₃ and the linear actuators 3, ₁ , 3 ₂ , 3 ₃ , {fe} = It can be expressed as [Ac] {ie} ... Here, [Ac] is a conversion matrix for converting current to force. That is, since the electromagnets 2 ₁ , 2 ₂ , and 2 ₃ are magnetic forces, force = constant × current value ² / distance ² is obtained, but within a predetermined range, approximately force≈constant × current value + constant value. Since the linear actuators 3 ₁ , 3 ₂ , and 3 ₃ are Lorentz forces, they can be expressed as force = constant × current value, and the conversion matrix [Ac] is calculated from such current values. It is a matrix having matrix elements for performing conversion into force. By substituting the expression and the expression into the expression, [E] {fe} + [C] [S] {dx '} + [K] [S] {dx} = 0 is obtained. By substituting, [E] [Ac] {ie} + [C] [S] {dx '} + [K] [S] {dx} = 0 is obtained. Therefore, the current vector {ie} is {ie} =-[E] ^-1 [Ac] ^-1 [C] [S] {dx '}-[E] ^-1 [Ac] ^-1 [K] [S] ] {Dx}. Therefore, each position sensor 4 ₁ , 4 ₂ , 4 ₃ ,
Based on the detection values of 4 ₄ , 4 ₅ , and 4 ₆ , the above-mentioned calculation is performed to move the electromagnets 2 ₁ , 2 ₂ and 2 ₃ and the movable coils 3 b of the linear actuators 3 ₁ , 3 ₂ and 3 _3. By feedback controlling the current to the center of gravity, the center of elasticity and the center of damping are aligned with the center of gravity, and when the compliance mechanism E moves, no rotational force acts on the movable body 1,
Only the translation is performed in the moving direction of the compliance mechanism E.

That is, as shown in FIG. 6, the detected values {dx} of the position sensors 4 ₁ , 4 ₂ , 4 ₃ , 4 ₄ , 4 ₅ , 4 ₆ .
(Step S1), the tilt of the movable body 1 is obtained as a component of the displacement vector {r} (step S2),
If this inclination is close to 0, it is determined that the elastic center S substantially coincides with the center of gravity G (step S3). On the other hand, when the inclination is relatively large, the position of the elastic center S is determined so that the inclination becomes smaller (step S4), and the feedback gain necessary for obtaining the desired current value is obtained (step S5). current electromagnets 2 _{1, 2} 2, 2 ₃ and the linear actuator 3 _1, 3 _2, 3 ₃ of the moving coil 3
It is given to b (step S6).

That is, the compliance mechanism E in FIG.
Is moving to the right and is accelerating, the movable body 1 tends to tilt at a large tilt angle φ with respect to the center line L of the compliance mechanism E as shown in FIG. Therefore, FIG.
As shown in (b), the electric currents to the moving coils 3b of the electromagnets 2 ₁ , 2 ₂ , 2 ₃ and the linear actuators 3, ₁ , 3 ₂ , 3 ₃ are adjusted so that the position of the elastic center S approaches the center of gravity G. If feedback control is performed to bring the elastic center S closer to the center of gravity, the inclination angle φ becomes smaller. If the elastic center S coincides with the center of gravity G of the movable body 1 as shown in FIG. It does not incline with respect to the center line L of the lianse mechanism E, but only translates in the direction of acceleration acting on the compliance mechanism E. Here, in the method of the present embodiment, not only the elastic center S but also the damping center D coincides with the center of gravity G, so that the movable body 1 does not tilt even when the acceleration changes.

(Embodiment 2) In Embodiment 1, the elastic center S and the damping center D are both controlled so as to coincide with the center of gravity G, but in this embodiment, the elastic center S and the damping center D are controlled. A method of individually controlling will be described. That is, the vector {fs} of the external force acting on the elastic center S
And the vector {f of the external force acting on the damping center D
Since the total force with d} is considered to be the total external force {f}, {f} = {fs} + {fd}, and for each external force vector {fs}, {fd},
Make sure that the static balance condition is satisfied. That is, [K] {rs} + {fs} = 0 ... a [C] {rd '} + {fd} = 0 ... b holds so that the electromagnets 2 ₁ , 2 ₂ , 2 ₃ and the linear actuator 3 The current to the movable coils 3b of ₁ , 3 ₂ , 3 ₃ is controlled. Where {rs} is the displacement vector in the coordinate system with the elastic center S as the origin, and {rd ′}
Indicates the time derivative of the displacement vector in a coordinate system with the damping center D as the origin. Considering separately for the elastic center S and the damping center D also electromagnetic force, the position sensor 4 _1, 4 _2, 4 _{3, 4} 4, 4 _5, 4 ₆ detected value of {dx}
On the other hand, the conversion to the displacement vector {rs} in the coordinate system having the elastic center S as the origin and the conversion to the displacement vector {rd} in the coordinate system having the damping center D as the origin are
It looks like this:

{Rs} = [Ss] {dx} ... a {rd} = [Sd] {dx} ... b where [Ss] and [Sc] are matrices determined by the structure of the compliance mechanism E, respectively. .. Also,
Electromagnetic force {f that acts on the movable body 1 by the electromagnets 2 ₁ , 2 ₂ , 2 ₃ and the linear actuators 3, ₁ , 3 ₂ , 3 _3.
The forces {fs} and {fd} acting on the elastic center S and the damping center D by e} can be expressed as follows.

{Fs} = [Es] {fe} ... a {fd} = [Ed] {fe} ... b where [Es] and [Ed] are the compliance mechanism E.
Is a transformation matrix determined by the structure of. As the electromagnetic force vector {fe}, use a current vector {ie} whose elements are the currents supplied to the electromagnets 2 ₁ , 2 ₂ , 2 ₃ and the movable coils 3 b of the linear actuators 3, ₁ , 3 ₂ , 3 _3. Can be expressed as {fe} = [Ac] {ie} ... And the current vector {ie} is the current vector {i that gives the electromagnetic force acting on the elastic center S.
s} and a current vector {id} that gives an electromagnetic force acting on the damping center D can be expressed as {ie} = {is} + {id}. Here, [Ac] is a conversion matrix for converting current to force. By substituting the expressions a, b and a, b into the expressions a, b, [Es] {fe} + [K] [Ss] {dx} = 0 [Ed] {fe} + [ C] [Sd] {dx '} = 0 is obtained, and by substituting the equations into these equations, [Es] [Ac] {is} + [K] [Ss] {dx} = 0 [Ed ] [Ac] {id} + [C] [Sd] {dx '} = 0 is obtained. Therefore, the current vectors {is}, {id}
Is {is} =-[Es] ^-1 [Ac] ^-1 [K] [Ss] {dx} {id} =-[Ed] ^-1 [Ac] ^-1 [C] [Sd] {dx '. } By substituting these expressions into the expression, {ie} =-[Es] ^-1 [Ac] ^-1 [K] [Ss] {dx}-[Ed] ^-1 [Ac] ^-1 [C] [ Sd] {dx '} is obtained. In this way, each position sensor 4 ₁ , 4 ₂ , 4
Each electromagnet 2 ₁ , 2 ₂ , 2 is controlled so that the positions of the elastic center S and the damping center can be individually controlled based on the detected values of ₃ , 4 ₄ , 4 ₅ , 4 ₆ and the time change of the detected values. ₃ and the currents to the movable coils 3b of the linear actuators 3 ₁ , 3 ₂ , and 3 ₃ can be feedback-controlled.

[0029]

As described above, the present invention is set so that the restoring force acting on the movable body can be expressed only by the displacement due to the translation along the coordinate axis and the angular displacement due to the rotation around each coordinate axis. With the elastic center at the origin of the Cartesian coordinate system, when the compliance mechanism moves, the compliance mechanism adjusts the restoring force that acts on the movable body so that the elastic center matches the center of gravity of the movable body. It is possible to prevent the moment from acting on it. That is, when the compliance mechanism moves, the movable body does not rotate but moves only in translation in the moving direction of the compliance mechanism.
This has an advantage that the movable body is less likely to collide with the compliance mechanism as compared with the case where the movable body is rotated. As a result, the compliance mechanism can be moved at a higher speed than before in a range in which the movable body does not collide with the compliance mechanism, and the assembly time can be shortened when used in an automatic assembly apparatus or the like. Also,
Since the rotational force does not act on the movable body, the vibration at the time of sudden stop can be damped relatively quickly, and the settling time can be shortened.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment, (a) is a schematic configuration diagram, (b) is a diagram illustrating a concept of an elastic center, and (c) is a diagram illustrating a concept of a damping center.

FIG. 2 is a diagram showing a relationship between displacement of a movable body and a restoring force in the embodiment, (a) is a translational diagram, and (b) is an explanatory diagram regarding a displacement corresponding to rotation.

FIG. 3 is a diagram illustrating a relationship between a displacement of a movable body and a damping force in the embodiment, (a) is a translational diagram, and (b) is an explanatory diagram regarding a displacement corresponding to rotation.

FIG. 4 is an explanatory diagram showing a relationship between a center of gravity and a damping center in the embodiment.

FIG. 5 is an explanatory diagram showing a moving state of a movable body when the method of the present invention is adopted.

FIG. 6 is an operation explanatory diagram of the present invention.

FIG. 7 is a diagram illustrating the concept of the operation of the present invention.

FIG. 8 is a schematic configuration diagram of a compliance mechanism used in the embodiment.

FIG. 9 is a perspective view of a main part of the compliance mechanism used in the embodiment.

FIG. 10 is an exploded plan view of a part of the compliance mechanism used in the embodiment.

11 is a sectional view taken along line IV-IV in FIG.

FIG. 12 is a plan view of a linear actuator used in an example.

FIG. 13 is a front view of a linear actuator used in an example.

FIG. 14 shows a schematic configuration of a compliance mechanism according to the present invention, (a) is a partially broken perspective view, and (b) is a sectional view.

FIG. 15 is an operation explanatory view showing a problem of the conventional example.

[Explanation of symbols]

1 movable body 2 ₁ electromagnet 2 ₂ electromagnet 2 ₃ electromagnet 3 ₁ linear actuator 3 ₂ linear actuator 3 ₃ linear actuator 4 ₁ position sensor 4 ₂ position sensor 4 ₃ position sensor 4 ₄ position sensor 4 ₅ position sensor 4 ₆ position sensor c ₁ Damping element c ₂ Damping element c ₃ Damping element c ₄ Damping element D Damping center E Compliance device G Center of gravity k ₁ Restoring element k ₂ Restoring element k ₃ Restoring element k ₄ Restoring element S Elastic center

Claims (1)

[Claims] 1. A posture control method for a movable body by a compliance mechanism, wherein a posture of the movable body is controlled by adjusting a restoring force and a damping force applied by the compliance mechanism to the movable body supported by the compliance mechanism. The origin of the Cartesian coordinate system is set as the elastic center so that the restoring force acting on the movable body can be expressed only by the displacement due to the translation along the direction and the angular displacement due to the rotation around each coordinate axis. A posture control method for a movable body using a compliance mechanism, wherein the restoring force acting on the movable body by the compliance mechanism is adjusted so that the elastic center coincides with the center of gravity of the movable body when moving.