JPH02283600A - Gravity compensating device - Google Patents

Abstract

PURPOSE:To compensate gravity to a developing object accurately and easily by setting the opposite sides of a quadrangle formed of an arm, a strip body, the developing object and the distance between rotation axes to be equal and rotating the arm so as to cancel the gravity of the developing object. CONSTITUTION:A strip body 2 is fitted at an arm 12 in such a way as to be vertically linked with a tip part H, and the arm 12 and the strip body 2 are set in such a way that the length of the strip body 2 is equal to the distance between the developing rotation axis O of an developing object 1 and the rotation axis O' of the arm 12, and the distance between the center of the rotation axis O' of the arm 12 and a strip body fitting point H is equal to the distance of the developing object 1, that is, a quadrangle formed of the developing object 1, the strip body 2, the arm 12 and the distance between the rotational centers of the developing object 2 and the arm 12 is set to have equal opposite sides. The moment, around the rotation axis O of the developing object 1, of the tensile force acting upon the strip body 2 is balanced with the rotational moment, around the rotation axis O, generated by the self-weight of the developing object 1 so as to cancel the influence of gravity acting upon the developing object 1.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a device that cancels out the effects of gravity, and in particular, the present invention relates to a device that cancels out the effects of gravity, and in particular, it is used on the ground to monitor the deployment characteristics of objects in space, such as antennas mounted on artificial satellites. This invention relates to a gravity compensator that allows for confirmation.

(Prior Art) With the full-scale use of space, including in the field of communications, there is an increasing demand for higher performance in space equipment mounted on space vehicles such as artificial satellites. For example, in the case of space antennas, the aim is to achieve high gain and large output, and to achieve this it is necessary to increase the structural diameter. On the other hand, these space equipment must be stored in a rocket fairing during launch, and are therefore subject to size restrictions. Expansion structure is a technology that solves this contradiction. This deployable technology involves folding the object into a small size for storage during launch, and automatically deploying it to its final shape using a built-in mechanism in space orbit. Various methods are used depending on the application.

Although these methods have great advantages as space structures, since the deployment operation is performed in outer space, the reliability and accuracy of deployment and the characteristics after deployment must be guaranteed, and they must be highly reliable. is asked. For this reason, deployment test methods on the ground that simulate the space environment are considered extremely important, and various methods have been devised to cancel the effects of gravity and the atmosphere. Regarding the atmosphere, it is possible to reduce it to an almost negligible level by slowing down the deployment speed of the deployable structure sufficiently, and the canceling device is aimed exclusively at gravity.

There is a device as shown in FIG. 2 that has means for canceling gravity. In this system, a developed object 1 is lifted up via pulleys (4a) and (4b) by a counterweight 3 attached to a band-shaped body 2 such as a flexible elastic wire. However, in this method, since the position of the pulley 4a on which the lifting strip 2 is hung is fixed, as the unfolded object 1 is expanded by the drive device A, the strip 2 makes an angle δ with respect to the direction of gravity. Therefore, the tension T applied to the strip has a component other than the direction of gravity, and the balance of forces set to compensate for gravity is disrupted.

In other words, if the unfolding angle of the unfolded object 1 is θ, and the length from the rotation axis 0 of the unfolded object to the suspension point P of the belt-shaped body is r, then the moment force calculated by the following equation occurs as a component other than the direction of gravity. .

T r (cosδsinθ+sinδCO8θ−5i
nθ) For this reason, conventionally, in order to remove this component, the angle δ between the strip and the gravity direction should be made small, and the lifting booth should be installed as high as possible. Due to limited space, it was difficult to reduce the error.

Additionally, there have been proposals for devices that correct the shortcomings of the above-mentioned methods (for example, Japanese Patent Laid-Open No. 62-281600:
According to this, the hanging pulley on which the strip-like object is placed is slidably supported by a slide rail, etc., so that the strip-like object always faces the direction of gravity so that it can move in accordance with the development of the object. This is what we are trying to do. However, such a device has the following problems. It uses the force T sin δ (tension applied to the belt) generated by the inclination δ of the belt with respect to the direction of gravity as the force for moving the hanging booth, and this force T sin δ is applied to the hanging pulley and the slide rail. The hanging pulley will not start moving unless the frictional force acting between the For this reason, the movement of the hanging pulley was not smooth, was uncertain, and had difficulty in tracking, and the band-like body could not maintain the direction of gravity, causing errors in gravity compensation.

Furthermore, the above-mentioned device has the following problems due to the spring or counterweight used as the gravity compensating means.

That is, in devices using springs, there is a problem in that not only is it difficult to set the spring tension, but also the influence of setting errors is large. In addition, in devices that use a counterweight, the counterweight moves in the anti-gravity direction as the object unfolds, but the counterweight is affected by the acceleration caused by this movement from the center of the object's expansion axis to the suspension point of the strip. There is a problem in that the distance θ is the expansion angle) is added to the gravitational acceleration, giving an error to the belt tension. Furthermore, there is a problem in that the counterweight swings left and right as it moves, which causes the tension of the band-shaped body to fluctuate, causing an error in gravity compensation.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and its purpose is to provide a device that can accurately and easily realize gravity compensation for a deployed object. be.

[Structure of the Invention] (Means for Solving the Problems) The gravity compensation device of the present invention includes a flexible elastic body such as a band-like body that lifts a deployable object, and a rotation center vertically above the deployment center of the deployable object. It consists of an arm and a driving means for driving this arm. Here, the length of the flexible elastic body such as the band-shaped body is equal to the distance between the deployment center of the deployable object and the rotation center of the arm, and the distance between the rotation center of the arm and the belt-shaped body attached to the arm is The distance between the center of development of the object and the attachment of the strip to the object is set to be equal to the distance, and the drive means for the arm is driven in synchronization with the rotation of the object.

Further, in order to detect the tension of the strip (2), a tension detection means (13) is provided on the strip (2).

Further, a rotation angle detection means is provided on the rotation axis O; 0- in order to detect the rotation angle of the arm and the unfolded object.

(Function) By rotating the arm in accordance with the rotation of the developed object, the developed object and the strip 1 can be rotated at any unfolding angle of the developed object.
A quadrilateral formed by the distance between the arm and the center of rotation of the developed object and the arm always forms a parallelogram. Therefore, the belt-shaped body can hang an unfolded object while always maintaining its vertical (gravity) direction.

Further, by the tension detection means provided on the band-shaped body and the rotation angle detection means provided on the rotation axis of the arm and the unfolded object,
It is possible to check whether the functions of the above-mentioned device are working properly.

(Example) Hereinafter, the gravity compensator of the present invention shown in FIG. 1 will be explained, with the same parts as in FIG. 2 being given the same reference numerals.

The unfolded object 1 has a rotation axis O in a direction orthogonal to gravity, and is unfolded around the rotation axis O by the first driving means A from vertically upward to horizontally. A rotation axis 1 is provided vertically above the rotation axis 0 of the developed object 1 and parallel to the rotation axis O, and a second arm 12 having approximately the same length as the developed object 1 is installed around this rotation axis O. It is provided to be rotationally driven by driving means B. A band-like body 5 is attached to the arm 12 so as to connect the tip end P vertically. The length of the band-shaped body 2 is the rotation axis O of the unfolded object 1 and the rotation axis 0' of the arm 12.
The distance between points H is equal to the distance between points H, and the distance between points H and the center of the rotation axis 0' of the arm 12 is equal to the distance between points H, and the distance from the center of the rotation axis 0' of the arm 12 to the belt-shaped body is The arm 12 and the strip 2 are set so that the distance between the points 2 and 2 is equal to the distance between the points 2 and 2. That is, the opposite sides of the quadrilateral formed by the developed object, the belt-like arm, and the distance between the centers of rotation of the developed object and the arm are set to be equal. Here, the rotational axis 0 of the developed object 1 of the tension acting on the strip 12
The surrounding moment balances the rotational moment around the rotation axis O due to the self-weight of the unfolded object 1, and cancels the influence of gravity acting on the unfolded object 1.

Further, the arm 12 that is rotationally driven around the rotation axis 1 by the second drive means B rotates in synchronization with the developed object 1 that is rotationally driven around the rotation axis 0 by the first drive means A. It is driven as follows.

This second driving means B may be of any type as long as it provides the same rotation to the arm 12 in synchronization with the developed object 1.

For example, the first and second driving means A and B of the unfolded object 1 and the arm 12 are configured with a step motor and a speed reducer, so that the rotations of their respective output shafts are synchronized and move in the same manner. This is done by driving this step motor and speed reducer.

Therefore, the arm 12 moves in the same way as the unfolded object 1,
Development 1. Arm 12. The quadrilateral formed by the belt-shaped body 2, the developed object 1, and the distance between the rotation centers of the arms 12 is the developed object 1.
always forms a parallelogram regardless of the angle of expansion. As a result, since the strip 2 always faces in the vertical direction, the tension acting on the strip 2 does not fluctuate, and the rotational moment of the developed object 1 around the rotation axis O and the moment of the tension acting on the strip 2 around the rotation axis O are always balanced, and highly accurate gravity compensation can be achieved for the unfolded object.

(13) is a tension detection means such as a load cell provided on the belt-shaped body (2), and detects whether or not the arm (12) and the deployed object (1) are rotating in synchronization. This is to detect whether only the equivalent amount of electric power is being lifted by the arm (12).

Although not shown, there are well-known potentiometers on the rotation axis 0 of the developed object (1) and the rotation axis 0' of the arm (12) for detecting the rotation angles of the developed object (1) and the arm (12) themselves. A means for detecting the rotation angle, such as a meter, is provided.

The detected rotation angle can be monitored by constantly displaying its output signal on a CRT (not shown) or the like.

By providing these means, it is possible to determine whether or not the rotation of the deployable object (1) and the arm (12) are performed synchronously. You can check whether it is being done or not.

Although the case where a step motor and a speed reducer are used as the first and second driving means has been described, the present invention is not limited to this, and the step motor may be used alone, or other motors may be used. Alternatively, other means such as a spring may be used.

Further, although the antenna has been described as an example of the target object, the present invention is not limited to this, but can be applied to structures in general that are required to cancel the influence of gravity.

[Effects of the Invention] As explained above, the gravity compensator of the present invention can always maintain the belt-shaped body on which the developed object is hung in the direction of gravity, regardless of the unfolding angle of the developed object, and can easily reduce the influence of gravity acting on the developed object. It has the effect of being able to cancel the gravity with high accuracy, and it is possible to provide a highly accurate gravity compensation device for performing ground tests of space deployable objects.

Furthermore, it has the effect of being able to confirm whether the gravity compensation function is operating correctly by the tension detection means provided on the band-shaped body and the rotation angle detection means provided on the rotating shafts of the unfolded object and the arm.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of the gravity compensation device of the present invention, and FIG. 2 is a schematic configuration diagram of a conventional gravity compensation device. DESCRIPTION OF SYMBOLS 1... Developed object 22... Band-shaped body, 0.0-... Rotating shaft 12... Arm, 13... Tension detection means. A: first driving means, B: second driving means. H... Attach the strip at the point, P... Near the hanging point of the strip.

Claims (3)

[Claims] (1) a deployable object having a rotating shaft at one end; an arm having a rotating shaft vertically above the rotating shaft; and a band-shaped body extending vertically downward from the other end of the arm and connected to the developing object;
A first driving means for rotating the expanded object around the rotation axis, and a second driving means for rotating the arm in synchronization with the driving of the first driving means, the arm, the belt-shaped body, Opposite sides of a quadrilateral formed by the distance between the unfolded object and the respective rotation axes of the developed object and the arm are set equal, and by rotating the arm, the gravity of the unfolded object is canceled. gravity compensator. (2) The gravity compensation device according to claim 1, wherein the belt-like body is provided with tension detection means for detecting tension applied to the belt-like body itself. (3) The gravity compensation device according to claim 2, further comprising rotation angle detection means for detecting the rotation angles of the developed object and the arm, respectively, on the rotation axis of the developed object and the rotation axis of the arm.