DD219719A1 - DEVICE FOR WEIGHT COMPENSATION IN INDUSTRIAL ROBOTS - Google Patents

Abstract

The invention finds application for weight balance of moving elements in industrial robots using spring elements. The object of the invention is to increase the mass of the gripper arm as a function of the angular position of the moving element without increasing the mass moment of inertia of the moving elements. The features of the invention consist in that a specially shaped cam plate is arranged on the movement elements, on whose curved path a traction means tensioned by a spring is wound up or unwound. By changing the radius of curvature as a function of the angle of rotation f of the cam and simultaneous change in the spring force, the required torque characteristic is realized. Fig. 1

Description

BAZ 642

Title of the invention Weight balancing device for industrial robots

Field of application of the invention

The invention relates to a device for weight balance of moving elements in industrial robots using spring elements.

Characteristic of the known technical solutions

Technical solutions have already become known which at least partly compensate the masses to be moved by industrial robots. The following principles are used:

1. the mass of the gripper barge is assigned to countering; (eg: PHM 4, IR 10, IR 60)

2. the masses of the gripper arms are compensated by counteracting tension or compression springs;

(eg: IR PHM 4 and PHM 40)

3. Use of so-called heart curves in the pivot points of gripper arms, act against the loaded with springs pressure rollers; (eg: DD-PS 0 154 282)

In the arrangement of countermeasures is first a complete balance of its own weight z. B. achieved a robot arm. This principle is technically meaningful if the counterweight is a necessary functional element, eg, electric motor. However, if only "dead" masses come into consideration as countermeasures, there is the disadvantage that the total mass to be moved increases and as the mass moment of inertia increases, the dynamic properties of the system deteriorate.

In the arrangements with counteracting tension or compression springs, the dynamic disadvantages are avoided. However, these spring arrangements have the disadvantage that they have a fixed characteristic and that they deviate significantly from the counterweight when moving in the case of articulated robots.

In the arrangement using heart curves, the required counter moments are achieved via the slope of the heart curve. As a result, the required characteristic curves can be reproduced exactly via the mathematically ascertained gradient curve. In the constructive and practical implementation of such devices, however, considerable design problems arise. In most cases, design-related pitch angle with less than 45 ° are required, whereby the applied by the pinch roller pressure force is a multiple of the restoring force to be generated. A disadvantage is the resulting high surface loads on the cam. '

Object of the invention

The object of the invention is to avoid the disadvantages of the known arrangements »

   '»·. Explanation of the essence of the invention

The invention has for its object to provide a device for balancing the weight of industrial robots, which realizes a Ausgleichskenrslinie over a wide range of motion using springs and thereby avoids surface forces acting on cams.

According to the invention, balancing torques are generated over a wide range of motion by virtue of the fact that a specially shaped curve or cam disk, upon rotation, unwinds a tensioning member tensioned by a spring. By changing the radius of curvature as a function of the angle of rotation of the cam and simultaneous change in the spring force, the required torque characteristic is realized. By choosing the curve shape so desired characteristics can be realized.

With this solution, a mass balance is created, the verraeidet high surface forces on the cams used. , '; i. · - :. ..

The weight compensation according to the invention can be accommodated in any joint of an industrial robot without substantially increasing the total mass. ,

Embodiment:

The invention will be described below with reference to an embodiment.

i ', .. · ·. , , · · ^: · Game explained in more detail.

Show it:

Fig. 1: a schematic diagram of erfiirdungsgemäßen device in conjunction with a «Hubgetriebe using rack and pinion;

FIG. 2 shows a schematic diagram of the mass compensation device according to the invention for lifting movements in conjunction with a traction means; FIG.

FIG. 3: a schematic representation of the mass equalization control

direction for a rotary joint; Fig. 4: end positions of the winding cucumbers according to Fig. 1 and Fig. 3; a; b) end positions over a rotation angle of Fig. 1; c; d) end positions over a Dr eh angle y of Fig. 3rd

In Figure 1, the generation of a constant AusgleichstnosBentes is reproduced for a lifting unit. The column 1, guided by guide rollers 2 carries a rack 4 and suit is a gear 3 in engagement. Axially on the gear 3, a cam 5 is fixed. The cam 5 with curved path 6 is connected to a traction means 10 and the traction means 10 is fixed by means of prestressed tension spring 7 on the frame 9. In Figure 2, the rack and the gear are replaced by a pull rope 13 and a guide roller 8. When moving the column 1, the pull cable 13 is wound on the curved path 6 der.Kurvenscheibe 5, wherein at the same time biased with tension spring 7 traction means 10 on the pulley 8 is wound up or unwound. The traction means 10 may be a steel strip, steel cable and roller chain u * ä.

The curves form | V (y) J are to be chosen so that starting from a balance of the device by the biasing force F _{0 of} the tension spring 7, taking into account the spring characteristic in any position of the device balance is established and remains. The basic relationship is that the generating moment of the wound Zugmittellänge (spring extension) and the effective radius of curvature r is proportional. Starting from the sufficiently long Zugmittel 10 and relatively long Zugfeder .7'Grundgleichung:

M (V) - r (y) VF _{0 +} r (f) 'C _f ' J '-j / r Xf) * + (^) ^8. ' dys with M (y) s generated at the curve

F ₀ a preload force of the tension spring

r (y) = radius depending on the angle of rotation of the cam

Cp = spring constant

Under certain conditions, you can calculate the required curve step by step.

Analog can be a compensation device of FIG. 2 for a rotary joint realize (without translation for y> ^ 180 °), wherein the Kurvenforiri z. B. can be determined by iteration method. When dimensioning this compensation, care must be taken that concave curve pieces are avoided, since then the traction means 10 is no longer fully in contact with the cam track 6 of the cam disk 5. :

Claims (6)

invention claim .1 -.- device for weight compensation of the Bewegenelenseente in industrial robots using spring el a th, characterized in that the element to be moved nit with a cam (5) is in connection, on the cam track (6) under the spring force of a Tension spring (7) stationary traction means (10) is applied and the traction means (10) with the cam (5) is firmly connected » 2. Device for weight balance according to item 1, characterized in that the shape of the cam (5), in particular the effective radius of curvature r ty), and 'the dimensions of the tension spring (7) determining the M'onentenkenn'iinie for the Mass balance are. 3. Device for the weight balance after point 1 and 2, characterized in that for realizing a longitudinal or lifting movement in a rotary motion a rack (4) with a gear (3) is engaged and the cam (5) firmly the toothed wheel (3) is connected, on whose cam track (6) the traction means (10) bears tangentially. 4. Weight-balancing device according to items 1 and 2, characterized in that / the cam disc (5) in the pivot joint (12) of a robot arm (11) is arranged. ^ 5 »device for the weight balance according to item 1 and 4, characterized in that the cam disc (5) is part of the robot arm and the kürvertbahn (6) on the lever arm (11) is formed. 6. Device for weight balance according to item 1 and 2, characterized in that the cam disc (5) in articulated robots relative to the frame (9) is fixed, the traction means (10) with the tension spring (7) on the lever ar m (11) of the Robot is attached and so the traction means (10) when changing the position of the lever arm (11) 'on the curved path (6) of the cam (5) is wound,