JP3142355B2 - Motion posture calculation device for parallel link mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for monitoring the movement posture of a parallel link mechanism used as a means for generating various rocking states in a flight simulator, a boat maneuvering simulator, and the like.

[0002]

2. Description of the Related Art For occupant training of aircraft and ships,
Various simulators have been put to practical use, in which a pilot trainer performs simulated driving while looking at a simulated field of view and a simulated instrument in front, and simulates the swaying of the cab at that time. The sway generator of these simulators is capable of giving three degrees of freedom movement of a heave movement (up and down movement), a pitch movement (pitch sway) and a roll movement (rolling sway). A motion that can give all six degrees of freedom motion, including dihedral motion (vertical motion), swivel motion (lateral motion), and yaw motion (sway around the vertical axis), is a general motion that can be generated. A number of links corresponding to the degrees of freedom are arranged in parallel between the motion base on which the operator's cab is mounted and the fixed base fixed on the floor surface to form one link mechanism. It is known to change the length of a link so as to generate each of the above-mentioned movements individually or in combination with a plurality of movements on a motion base. In this specification, such a link mechanism is referred to as a parallel link mechanism in the sense that a plurality of links are arranged in parallel.

By the way, in order to generate the movement of an aircraft or a ship faithfully as required by using the parallel link mechanism, a cockpit or a motion base for each independently time-varying link length is required. There is a need for a means for monitoring the attitude of the cockpit. As a related technique, the amount of stroke of each of the six hydraulic cylinders that are feedback-controlled and used as a link is used as information, and the six-degree-of-freedom movement attitude of the cockpit is used. Has been devised ("Simulator movement and posture monitoring device" (Japanese Patent Laid-Open No. 57-208407)). There are various methods for realizing the inverse conversion operation device, but in many cases, an operation method represented by the following equation (1) is adopted.

X _{K + 1} = x _K + J ⁻¹ (x _K ) { _{ld k} −l _K }
(1) The convergence discriminant expression | x _{K + 1} −x _K | ≦ constant value J ⁻¹ (x _K ) is a matrix corresponding to the inverse matrix of the Jacobi matrix used in the serial link mechanism. _dk , n-th position / posture of motion base
The next approximation is x _K and the link length is l _K (= f (x _K ))
By repeating this equation (1), the motion base
The position / posture of the robot is required (Nakajima et al., "Development of Controller for Parallel Link Manipulator", 9th Annual Conference of the Robotics Society of Japan, November 1991).

[0005]

However, the above equation
In order to obtain the motion-based attitude with respect to the time-varying link length using the conventional calculation method shown in (1), it is assumed that the link length is constant at each sampling interval. However, the convergence calculation must be repeated until sufficient accuracy is obtained each time, and the motion-base oscillating posture cannot be calculated with high accuracy and high speed.

[0006] An object of the present invention is to solve the above-mentioned problems and to provide a module.
It is an object of the present invention to provide a motion / posture calculating device for a parallel link mechanism capable of determining a swinging posture of a shock base with high accuracy and high speed.

[0007]

According to a first aspect of the present invention, there is provided a motion / posture calculating apparatus for a parallel link mechanism, wherein a motion base is fixed by n links whose lengths can be freely changed. In the n-degree-of-freedom parallel link mechanism supported on a link, there is provided a virtual mechanism obtained by numerically modeling an actual link mechanism, and this virtual mechanism adds an inverse Jacobian matrix to the derivative l ′ (t) of the link length. J- ¹ (x (t)) is multiplied by the motion / base position / posture differential variation x '(t) to integrate the motion base position / posture x (t). And the virtual link length l (t) is calculated from the position / posture x (t). The virtual link length l _d (t) at time t is calculated by the virtual mechanism. The result calculated by the above virtual mechanism using the value obtained by multiplying the value obtained by subtracting the virtual link length l (t) by the constant K. The resulting mode - Shonbe - those having an arithmetic unit to scan the position / posture x _d (t) the actual position / posture.

The motion posture calculating device for a parallel link mechanism according to a second aspect of the present invention has a structure in which a motion base is supported on a fixed base by n links whose lengths can be changed freely.
In the parallel link mechanism having a degree of freedom, a virtual mechanism having a numerical model of an actual link mechanism is provided, and this virtual mechanism converts an inverse Jacobian matrix J ⁻¹ (x (t)) into a differential value l ′ (t) of the link length. Is integrated to obtain the position / posture x (t) of the motion base, and the position / posture x (t) of the motion base is obtained. (t), the virtual link length l (t) is calculated. From the actual link length l _d (t) at time t, the virtual link length l (t) calculated by the virtual mechanism is calculated. A motion base obtained as a result of calculation by the virtual mechanism using a value obtained by multiplying the subtracted value by a constant K and adding the differential value of the link length l _d (t) to the value, is used. Is provided with an arithmetic unit for setting the position / posture x (t) of the above to the actual position / posture.

[0009]

FIGS. 1 and 2 are block diagrams of a control system showing the operation method of the operation device according to the first and second aspects of the present invention, respectively. Both have a common point in that a transmission element K is obtained by multiplying a constant K by a value obtained by subtracting the length l (t) of the virtual link calculated by the virtual mechanism from the length (vector) of the link at time t. . The operation method according to the first invention has a
The differential method s (link length l _d (t)
(Differential term of (vector)).

Therefore, first, each transmission element f (x (t)), J ⁻¹ (x
(t)) and 1 / s will be briefly described.

F (x (t)): f (x (t)) is an n-dimensional vector x (t) representing the position / posture of the motion base, and the elements are represented by respective link lengths l. _i (t) (i = 1,2,
3, ..., n)

[0012]

(Equation 1)

Represents the inverse kinematics calculation of the parallel link mechanism, which has the following relationship: l (t) = f (x (t)).

J ^-1 (x (t)): J (x (t)) is a function f (x (t))
And J ⁻¹ (x (t)) is its inverse matrix (inverse Jacobian matrix). J ^-1 (x (t)) represents the relationship between the vector l '(t) representing the speed of the link and the vector x' (t) representing the speed of the motion base, and x '(t) = J ^-1 (x (t)) l '(t).

1 / s: 1 / s represents an integral element.

The operation method according to the first aspect of the invention can be applied to the case where the time change of l (t) is rapid due to the effect of the differential element s. On the other hand, the operation method of the second invention is applied when the time change of l (t) is relatively slow. Therefore, in consideration of the high-speed operation of the parallel link mechanism, it can be said that the operation method of the first invention is more ideal than the operation method of the second invention.

Therefore, the stability of the control system shown in FIG. 1 will be described here.

Output of motion base (position / posture) x
Suppose that the speed of (t) can be controlled as follows. x '(t) = u (t) (2) where u (t) is a speed command input to the motion base.

There is a relationship between the link displacement l (t) and the motion base output x (t) as follows: l (t) = f (x (t)) (3) .

[0020] In this case (3) l from equation '(t) = J (x (t)) x' (t) ··· (4) is obtained by modifying this x '(t) = J ^{- 1} (x (t)) l '(t) (5) Here, J (x (t)) is a regular matrix.

[0021] (2) u (t) with respect to formula ^{= J -1 (x (t)} ) {l 'd (t) + K (l d (t) -f (x (t))} ··· (6) becomes Fi - Given to feedback, x '(t) = J -1 (x (t)) {l' d (t) + K (l d (t) -f (x (t))} · .. (7) holds, and from equations (3), (5) and (7), J ⁻¹ (x (t)) l ′ (t) = J ⁻¹ (x (t)) ｛l ′ _d (t) + K (l _d (t) −l (t))｝ J ⁻¹ (x (t)) ｛l ′ _d (t) −l ′ (t) + K (l _d (t) −l (t ))｝ = 0 .. (8) holds.

[0022] J (x (t)) because it was assumed to be a regular matrix _{l 'd (t) -l'} (t) + K (l d (t) -l (t)) = 0 ··· ( 9) always holds.

Here, if it is defined that l _d (t) −l (t) = e (t), e ′ (t) + Ke (t) = 0 (10) When this is solved, e (t) = E ^-Kt e (0) (11). If K is selected as a positive definite matrix or a positive real number, the error e (t) converges with time.

At this time, in the control system of FIG. 1, l _d (t) = f (x (t)) (12), so that x (t) at that time is l _d (t) = f (x
_d (t)).

Next, assuming that there is no error associated with the numerical integration required for the simulation of the virtual mechanism, a calculation error by the calculation method according to the present invention is obtained.

The seek given l _d (t) to _{l d (t) = f (} x d (t)) and (13) becomes x _d (t) at high speed and with high precision the present invention Is the purpose. Here, the function f represents the relationship between x _d (t) and l _d (t), but cannot generally be solved analytically.

The calculation error of x _d (t) is the length of the link corresponding to it, and e (t) = f (x (t)) − f (x _d (t)) (14) I will evaluate it.

Here, x (t) is the position / posture of the motion base calculated at time t.

In this operation method, the calculation error e (t) is (1
From equation (0 ), it can be expressed as e ' (t) =-Ke (t) (15), and can be calculated as e (t) = e- ^Kt e (0) (16). Here, e (0) = x (0) −x _d (0) (17), and the convergence time of the error is represented by the time change as long as l _d (t) can be first-order differentiable with respect to time. Irrespective of l _d (t), the parameter K can be freely selected.

On the other hand, in the conventional method, as described above, it is necessary to repeat the convergence calculation many times at each sampling interval until sufficient accuracy is obtained each time. In the calculation method according to the present invention, the same convergence calculation needs to be performed only once at each sampling interval, and the calculation error converges to zero with time (the number of calculations). Further, once the calculation error becomes zero, the position / posture of the motion base can be obtained without error.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 3 shows a ship maneuvering simulator using a six-degree-of-freedom parallel link mechanism. Reference numeral 1 denotes an operator cab imitating a hull shape, and the operator cab 1 is a disk-shaped motion base.
Mounted on the surface 2. The motion base 2 is
It is supported by six hydraulic cylinders 4 to 9 arranged on a fixed base 3 fixed to the floor surface. Both ends of these hydraulic cylinders 4 to 9 are provided with bearings 10 to 12 provided at three places on the fixed base 3 and bearings 13 to 15 provided at three places on the lower surface of the motion base 2. Supported. The bearings 10 to 12 on the fixed base 3 side rotatably support the bases of two adjacent hydraulic cylinders, and the bearings 13 to 15 on the motion base 2 side are fixed bases. Adjacent two supported by different bearings 10 to 12 on the
The distal ends of the hydraulic cylinders are rotatably supported. Reference numerals 16 to 21 denote electric hydraulic servo valves mounted on the hydraulic cylinders 4 to 9, respectively.
21 operate the respective hydraulic cylinders 4 to 9 by signals obtained from a control circuit (FIG. 4) described later. 22
Numerals 27 indicate displacement detectors for detecting displacements of the hydraulic cylinders 4-9.

In FIG. 4, reference numeral 30 indicates the motion characteristics of the ship in accordance with the motion conditions of the ship, and the movement of the surge, sweep and heave, which is the motion of the ship in three axial directions, and the motion of the ship. It outputs a six-degree-of-freedom movement command signal _xc (t) for performing a six-degree-of-freedom movement obtained by combining each of the yaw, pitch and roll movements, which are rotational movements around an axis, and the above-mentioned respective movements. A motion calculation processor 31, a coordinate converter 31 for converting the six-degree-of-freedom motion command signal x _c (t) into a displacement command signal l _c (t) for each of the hydraulic cylinders 4 to 9, and 32 a adder 32a and a servo Amplifier 3
2b is a servo control device for controlling the displacement of each of the hydraulic cylinders 4 to 9.

Reference numeral 33 denotes a motion / posture calculating device according to the first invention. In this embodiment, the motion / posture calculating device 33 comprises a displacement detector 22 to 27 for detecting the actual displacement of each of the hydraulic cylinders 4 to 9. From the cylinder length l _d (t) (six-component vector) at time t obtained from the signal, the six-degree-of-freedom movement posture of the motion base 2 is calculated, and the position / posture x _d ( t) is output. That is, in the present embodiment, the arithmetic device which is a main part of the exercise posture arithmetic device 33 has a virtual mechanism obtained by numerically modeling the actual 6-DOF parallel link mechanism, and the actual cylinder length l _d (t) Is obtained by multiplying a value obtained by subtracting the virtual link length 1 calculated by the virtual link mechanism from the above by a constant K, and adding the derivative value l _d ′ (t) of the cylinder length l _d (t) to the value. The position / posture x _d (t) of the motion base 2 obtained as a result of virtually moving the virtual mechanism with the value is output as the actual position / posture (see FIG. 1).

Numeral 34 denotes an actual position / posture x _d (t) of the motion base 2 output from the motion / posture calculation device 33 and a six-degree-of-freedom motion command signal x _c (output from the motion calculation processing device 30). t) is inputted, and the exercise performance evaluation device evaluates the control characteristics of the ship maneuvering simulator.

Next, the operation of this embodiment will be described.

The six-degree-of-freedom motion command signal x _c (t) output from the motion calculation processing device 30 is input to the coordinate conversion device 31, where the displacement command signal l for each of the hydraulic cylinders 4 to 9 is input.
Converted to _c (t). That is, in the coordinate conversion device 31,
A function operation represented by l _c (t) = f (x _c (t)) is performed. The displacement command signal l _c (t) is input to the servo control device 32.

On the other hand, the displacement signals output from the displacement detectors 22 to 27 are used as respective position feedback signals of the servo control device 32, and the servo control device 3
2 is input to each adder 32a, and each of the hydraulic cylinders 4 to 9
Is compared with the displacement command signal l _c (t). In this case, when there is a deviation signal in the adder 32a, the motion base 2 performs a combined operation by the hydraulic cylinders 4 to 9 via the servo amplifier 32b so that the deviation signal becomes zero. . At this time, in order to grasp the control state of the motion base 2, it is necessary to observe the actual motion posture of the motion base 2.

Therefore, the motion / posture calculating device 33 calculates the position / posture x _d (t) of the motion base 2 from the actual cylinder length l _d (t) at time t based on the signals of the displacement detectors 22 to 27. ) Is detected. That is, the motion / posture calculation device 33 performs the calculation of the above equation (7) by using the calculation device, and calculates x _d (t) obtained as a solution to the motion base.
And outputs the actual position / posture of the exercise 2 to the exercise performance evaluation device 34. In exercise performance evaluation device 34, by comparing the output signal x _c of the output signal x _d (t) and the motion calculation processing unit 30 of the motion and orientation calculation unit 33 (t), mode - Shonbe - of scan 2 6 free The position accuracy and responsiveness of each degree motion component are calculated, and the control state of the motion base 2 is evaluated.

As described above, the motion and posture calculation device 33 according to the present invention only needs to perform the convergence calculation for obtaining the solution x _d (t) of the equation (7) once at each sampling interval.
Further, once the calculation error becomes zero, the position / posture x _d (t) of the motion base can be obtained without any error. Accuracy can be obtained. Therefore, the control state evaluation of the motion base 2 by the exercise performance evaluation device 34 can be made highly reliable, and as a result, highly accurate control can be realized.

The exercise posture calculating device according to the present invention comprises:
The present invention can be applied not only to a parallel link mechanism having six degrees of freedom but also to monitoring of a movement posture of a parallel link mechanism having three or more degrees of freedom.

When the time change of l _d (t) is gradual, a system in which the differential value l _d ′ (t) is not added, ie, the second
Approximate x _d (t) can also be obtained by using the calculation method of the invention of the invention.

[0043]

In summary, according to the present invention, since the position / posture of the motion base can be obtained at a high speed, highly accurate control can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a calculation method according to the present invention.

FIG. 2 is a block diagram showing a calculation method according to the present invention.

FIG. 3 is a schematic configuration diagram of a ship maneuvering simulator using a six-degree-of-freedom parallel link mechanism.

FIG. 4 is a block diagram showing a simulator control circuit provided with the exercise posture calculating device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control room imitating ship hull 2 Motion base 3 Fixed base 4-9 Hydraulic cylinder used as link 13-15 Bearing 16-21 Electrohydraulic servo valve 22-27 Displacement detector 30 Motion calculation Processing device 31 Coordinate conversion device for conversion 32 Servo control device 32a Adder 32b Servo amplifier 33 Exercise / posture operation device according to the present invention 34 Exercise performance evaluation device

Continuing on the front page (72) Inventor Kazuhiro Kosuge 2-10 Kuroishi, Narumi-cho, Midori-ku, Nagoya-shi, Aichi Prefecture 5-103 Joint Tatemono Takinosui House 5-103 (72) Inventor Toshiki Kozuka 3-1-1, Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Tojin Technical Center (72) Inventor Tomio Mizuno 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawa Shima Harima Heavy Industries Co., Ltd. Tojin Technical Center (56) References Kazuhiro Kosuge, 4 others, "Forward Kinematics Computational Algorithm for Stewart Platform Parallel Link Manipulator", Journal of the Robotics Society of Japan, 1993, Vol. 11, No. 6, p. 849-855 Kazuhiro Kosuge, et al., "Force Analysis of Parallel Link Manipulators," Proc. Of the 10th Robotics Society Conference, October 31, 1992, p. 761-762 (58) Field surveyed (Int. Cl. ⁷ , DB name) G06F 19/00 110 F16H 21/46 G09B 9/06 G09B 9/14 JICST file (JOIS)

Claims (2)

(57) [Claims] An actual link mechanism is numerically modeled in an n-degree-of-freedom parallel link mechanism in which a motion base is supported on a fixed base by n links whose lengths can be freely changed. The virtual mechanism has a virtual mechanism. The virtual mechanism calculates the position / posture of the motion base obtained by multiplying the differential value l ′ (t) of the link length by the inverse Jacobian matrix J ⁻¹ (x (t)). The differential change x '(t) is integrated to obtain the position / posture x of the motion base.
(t), and a virtual link length l (t) is calculated from the position / posture x (t), and the virtual mechanism is calculated from the actual link length l _d (t) at time t. Multiply the value obtained by subtracting the virtual link length l (t) calculated in the above by a constant K,
Using the value obtained by adding the differential value of the link length l _d (t) to that value, the position / posture x (t) of the motion base obtained as a result of calculation by the virtual mechanism using the value obtained. A motion and posture calculation device for a parallel link mechanism, comprising a calculation device for setting an actual position / posture. 2. An n-degree-of-freedom parallel link mechanism in which a motion base is supported on a fixed base by n links whose lengths can be freely changed, an actual link mechanism is numerically modeled. The virtual mechanism has a virtual mechanism. The virtual mechanism calculates the position / posture of the motion base obtained by multiplying the differential value l ′ (t) of the link length by the inverse Jacobian matrix J ⁻¹ (x (t)). The differential change x '(t) is integrated to obtain the position / posture x of the motion base.
(t), and a virtual link length l (t) is calculated from the position / posture x (t), and the virtual mechanism is calculated from the actual link length l _d (t) at time t. The position / posture x _d () of the motion base obtained as a result of calculation by the above-described virtual mechanism using a value obtained by multiplying the value obtained by subtracting the virtual link length l (t) calculated in the above by a constant K, is used. a motion / posture calculation device for a parallel link mechanism, comprising a calculation device for setting t) as an actual position / posture.