JPH0691583A - Damping mechanism of robot - Google Patents

Abstract

PURPOSE:To offer the damping structure of a robot caused to accomplish damping operation by adding a vibration damping structure in which a balance spring used for gravity compensation of the robot is used as its dynamic vibration absorbing member. CONSTITUTION:A damping mechanism of a robot 5 provided with a balance spring 2 for gavity compensation of a robot element arranged on the robot element has, for example, the natural frequency of the balance spring 2 set nearly equal to the natural frequency of a vertical arm 1 and has a vibration damping means 4 connected to the balance spring 2. Thus, by setting the natural frequency of the balance spring 2 nearly equal to the natural frequency of the vertical arm 1, vibration of the vertical arm 1 is absorbed and, furthermore, by connecting the vibration damping means 4 to the balance spring 2, damping effect of the vertical arm 1 can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping mechanism for a robot that suppresses resonance vibration associated with the driving operation of the robot and allows smooth and accurate control of the robot operation.

[0002]

2. Description of the Related Art Most industrial robots have an unstable cantilever structure, and elastic components such as a speed reducer are present in the power transmission system. In addition, when a large acceleration / deceleration occurs during operation, the natural frequency of the mechanical system is excited and residual vibration remains,
It adversely affects the motion control of the robot hand, which is a tip motion element. For such vibration, it is effective to add a damping element to the robot mechanism. As a conventional configuration in which a damping system is added to the mechanical system itself, Japanese Patent Laid-Open No. 59-175
Some are disclosed in Japanese Patent Publication No. 991. As shown in FIG. 4, the vibration damping member 30 is inserted in the power transmission path to absorb the vibration of the drive system.

[0003]

In the case of the technique of absorbing vibrations by the vibration isolating member in the above-mentioned conventional example, it is necessary to make the vibration isolating member soft to some extent in order to effectively suppress the vibration. Increasing the vibration damping effect causes a problem that adversely affects the accuracy of the robot. The present invention was made in view of the above problems, and a vibration damping mechanism for a robot that performs a vibration damping action by adding a vibration damping structure using a balance spring used for gravity compensation of the robot as a dynamic vibration absorbing member. It is intended to provide a structure.

[0004]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the means adopted by the present invention is a vibration damping mechanism of a robot in which a balance spring for gravity compensation of the robot element is provided in the robot element. A natural vibration frequency of the spring is set to be substantially equal to the natural frequency of the robot element, and vibration damping means is connected to the balance spring.

[0005]

According to the present invention, the lateral vibration of the balance spring provided for gravity compensation of the industrial robot is used as a dynamic vibration absorbing member, and the natural frequency of the balance spring is almost equal to the natural frequency of the robot element. By setting the same, the vibration of the robot element can be absorbed, and the vibration damping effect of the robot element can be improved by connecting the vibration damping means to the balance spring.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. still,
The following example is an example embodying the present invention and does not limit the technical scope of the present invention. Figure 1
FIG. 2 is a schematic diagram showing a vibration damping mechanism of a robot according to an embodiment of the present invention, and FIGS. 2 and 3 are structural explanatory views for explaining the operation principle of the vibration damping mechanism according to the embodiment. FIG. 1 is an example in which the vibration damping mechanism of the present invention is applied to a vertical arm of an articulated robot.
In the robot 5, a balance spring 2 is attached to the vertical arm 1 of the robot 5 so as to be balanced with gravity at a reference position so as to balance with gravity. A concentrated weight 3 is arranged at the center of the balance spring 2 for adjusting the natural vibration. A dashpot 4 is provided between the concentrated weight 3 and the vertical arm 1 in order to add a vibration damping effect. The vibration damping mechanism having the above-described configuration applies a gravity compensation force to the vertical arm 1, and when the vertical arm vibrates, the balance spring 2 vibrates, and this vibration is absorbed by the dashpot 4. The operation principle of the vibration damping mechanism will be described with reference to FIGS. FIG. 2 is shown as a one-link manipulator having a balance spring for gravity compensation. Further, the balance spring has a density of 0 and has a concentrated mass in the central portion. When the kinetic equation of the system shown in FIG. 2 is derived, the kinetic energy and the strain energy are approximately represented by Equations 1 and 2.

[Equation 1]

[Equation 2] However, θ: Arm angle displacement x: Lateral vibration displacement from the balance position of the mass on the balance spring I _a : Arm inertia moment m: Balance spring mass T: Balance spring tension α: Balance spring mounting angle K: Spring constant of the speed reducer l: Distance from the center of rotation of the arm to the balance spring mounting position r: Length of the balance spring / 2 2 From Equations 1 and 2, the Lagrange's method is used to derive the equation of motion. It becomes like 4.

[Equation 3]

[Equation 4] Here, if cosα >> θ / 2 * sinα and the velocity term is ignored, Formulas 3 and 4 can be approximated by Formulas 5 and 5 below.
Can be rewritten to 6.

[Equation 5]

[Equation 6] Furthermore, when Z = θ− (2 / lcosα) x is set and Equations 5 and 6 are modified, Equations 7 and 8 can be written.

[Equation 7]

[Equation 8] Equations 7 and 8 are equivalently the same as when the dynamic damper is attached to the vibration system shown in FIG. Therefore,
Vibration can be reduced by adjusting the natural frequency of the lateral vibration of the balance spring to be approximately equal to the natural frequency of the robot arm. Further, by using a material having a high damping capacity as the balance spring material, and further by adding a damping mechanism to the balance spring, the damping effect can be further enhanced. That is, more effective damping can be achieved by selecting the mass and the damping coefficient based on the well-known optimal design theory of the dynamic vibration reducer.

[0007]

As described above, according to the present invention, the lateral vibration of the balance spring provided for gravity compensation of the industrial robot is used as a dynamic vibration absorbing member, and the natural frequency of the balance spring is set to the natural frequency of the robot element. By setting the frequency substantially equal to the vibration frequency, the vibration of the robot element can be absorbed, and the vibration damping effect of the robot element can be improved by connecting the vibration damping means to the balance spring.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a vibration damping mechanism of a robot according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation principle of the vibration damping mechanism according to the embodiment.

FIG. 3 is an explanatory diagram showing an operation principle of the vibration damping mechanism according to the embodiment.

FIG. 4 is a perspective view showing a vibration damping structure of a robot according to a conventional example.

[Explanation of symbols]

 1-Vertical arm 2-Balance spring 3-Concentrated mass 4-Dashpot (vibration damping means) 5-Robot

Claims (1)

[Claims] 1. A vibration control mechanism for a robot, wherein a balance spring for gravity compensation of the robot element is provided in the robot element, and the natural frequency of the balance spring is set to be substantially equal to the natural frequency of the robot element. A vibration damping mechanism for a robot, characterized in that a dynamic vibration absorbing means is connected to the balance spring.