JPH0583352B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a robot used for work on a straight track. This robot can be used for work on a straight track, such as deburring straight sections. Work on straight tracks is in great demand in industry, and the robot of the present invention can be widely used as an industrial robot.

[Background of the invention]

As shown in Figures 3 and 4, 6-degree-of-freedom articulated robots are often used as industrial robots, but the above-mentioned articulated robots cannot perform tasks on straight tracks that do not require very complex movements. It ends up being expensive. In fact, the work that is being automated in industry is not limited to work on complex curved tracks, but there is also a high demand for work on straight tracks. Therefore, it is suitable for working on straight tracks,
There is a need for versatile robots that can be adapted to suit different work purposes.

For example, many conventional deburring devices use the above-mentioned articulated industrial robot. As shown in FIG. 3, the structure includes a method in which the deburring tool 3' is fixed, the robot 1 grips the workpiece 2a to be deburred, and the robot 1 moves the workpiece 2a to remove the burr, and the method shown in FIG. A method is used in which the workpiece 2b is fixed, the robot 1 grips a deburring tool 3', and the deburring tool 3' is moved to remove burrs. However, while the conventional 6-degree-of-freedom articulated robot used here can perform most complex tasks, it
Since the robot operates based on the movement of individual joints, coordinate transformation between the orthogonal coordinate system and the joint coordinate system is required, making control complex. Further, the control device for this purpose also becomes large-scale, and there is a problem that the entire device becomes expensive. Furthermore, since the control is complicated, teaching work is time-consuming and operation is not easy. Of course, the above problems are unavoidable when work requiring complex curved trajectories is required. However, in operations performed on straight tracks, where demand is relatively high, it is necessary to solve the above-mentioned problems.

Furthermore, since there is a limit to the size of the arm of an articulated robot, there is a limit to the size of the object to be worked on in terms of the range of motion. Therefore, it is not suitable for working with large or long objects.

Furthermore, it is extremely difficult to draw accurate straight-line trajectories with the current control level of articulated robots.
The reality is that only work with low linear accuracy can be done on straight sections.

At present, no robot has yet been proposed that solves the above-mentioned problems, can sufficiently handle various simple tasks, can be applied to various tasks, and is versatile.

[Purpose of the invention]

The purpose of the present invention is to realize a robot with an inexpensive device that has good linear trajectory accuracy and is easy to control, and even if the object to be worked on is relatively large or long, the stroke can be adjusted accordingly. Take it long,
Furthermore, it is an object of the present invention to provide a deburring robot on a straight track that allows easy teaching of work programs.

In addition, we provide a deburring robot device that allows stable machining accuracy to be obtained and prevents damage to the tool because the tool gripped by the robot deburrs with a constant pressing force against the workpiece. It's about doing.

[Summary of the invention]

In order to achieve the above object, the robot for working on a linear track of the present invention deburrs the tip of the servo-driven three-degree-of-freedom linear motion mechanism through a first detection means for detecting force and a robot hand. A deburring robot device that continuously cuts off burrs generated on the object by supporting a tool for moving the object and moving the tool over the object, and detecting the position of the robot hand. a second detection means for
A matrix defining the motion characteristics of the tool, that is, a virtual mass, a virtual spring constant, and a virtual viscosity constant, is given to the control unit that controls the robot hand and the tool, and each of the above-mentioned constants, the detection result of the first detection means, and the second The object of the present invention is to include a calculating means for calculating the moving speed of the robot based on the deviation between the actual position of the robot's hand and the target value determined by the detecting means.

The drive unit of the robot of the present invention has three parts: X, Y, and Z.
A linear motion mechanism section 4 is employed in which the respective axes are orthogonal to each other and can be slid and moved. Therefore, the structure of the driving part can be simplified and a highly accurate straight trajectory can be obtained. In addition, in position control, the robot of the present invention is driven by arms in the three axes of X, Y, and Z that are orthogonal to each other, which eliminates the need for complex coordinate conversion work required for conventional articulated robots, and improves control. It can be easily made into a robot. Furthermore, by adopting a simple control method, the control device can also be downsized. Furthermore, since the complicated servo drive for teaching was limited to the minimum three degrees of freedom necessary for positioning in the orthogonal coordinate system, teaching could be simplified. Furthermore, by installing a force sensor between the hand and the 3-degree-of-freedom linear motion part, during teaching, by setting the target value, viscosity, and spring constant, the unevenness of the burr can be reduced even for burrs with complex shapes. You can set the feed speed of the hand so that the cutting force is constant and cut with a constant pressing force.

As shown in Figure 1, an elastic body (or elastic mechanism)
By adopting 3a, the force applied to the deburring tool is softened and the degree of force applied is adjusted. Therefore, it is possible to flexibly deal with sudden changes in the deburring surface and prevent the tool from breaking or cutting into the object. As shown in FIG. 1, by employing an elastic body (or elastic mechanism) 3a, the force applied to the deburring tool is softened and the degree of application of the force is adjusted. Therefore, it is possible to flexibly deal with sudden changes in the deburring surface and prevent the tool from breaking or cutting into the object.

In a preferred embodiment, as shown in FIG.
A force sensor 18 is provided between the rotation mechanism section 5 and the robot hand 3, which is capable of detecting at least one component of force (including torque) and six components at most.

With this configuration, the force applied to the robot hand 3 can be monitored, so that it is possible to prevent the work object, tools, etc. of the robot hand from being destroyed due to abnormal force being applied to the robot hand 3 during work. In particular, in embodiments in which a deburring tool is provided at the tip of the linear motion mechanism, a constant pressing force can be ensured by employing the force sensor 18, so the deburring tool can be program-controlled to the vicinity of the target, and the subsequent The position and orientation control of the deburring tool can be automatically taught using software by searching with a force sensor. In other words, offline programming is also possible.

In another preferred embodiment, as shown in FIG. 1, a one-degree-of-freedom rotation mechanism and a target part are provided that allow the robot to position the target object in at least two different positions using an easily controllable drive device. The object positioner 6 includes a gripping mechanism and an object positioner 6.

With this configuration, work can be done in areas that are difficult to work with the 3-degree-of-freedom linear motion mechanism and the 2-degree-of-freedom rotation mechanism at the wrist.
By changing the posture of the object using the object positioner 6, the work can be performed.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the overall configuration of the robot of this embodiment. As shown in FIG. 1, the robot of this embodiment includes a linear motion mechanism section 4 consisting of three axes, X, Y, and Z, a robot hand 3, a rotation mechanism section 5 constituting a wrist section in between, and an object position control mechanism. It is composed of an object positioner 6 that changes the position of the object.

Therefore, first, the linear motion mechanism section 4 will be explained.
Figure 2 shows the structure of the X axis. This mechanism transmits the rotational motion of the servo motor 7 via a pulley 8 and a belt 9 to a male screw (here, a ball screw is used) 11 supported by a guide 10. As the male screw 11 rotates, the female screw 12 moves linearly. The female thread 12 is connected to the slide bearing 14 on the guide rail 13 of the linear motion component and the plate 1.
5, a trajectory with good linear accuracy can be obtained by the driving force of the servo motor 7. In order to perform position feedback control of the slide bearing 14, which is a moving part, the rotation of the servo motor 7 is managed by an encoder. Although not used in this device, it is also possible to attach a linear scale to the guide rail 13 to directly manage the position of the slide bearing. X・Y・
The Z three-degree-of-freedom linear motion mechanism can be constructed by attaching three of the above-mentioned X-axis uniaxial mechanisms to each plate 15.

Next, in this embodiment, as shown in FIG. 1, a deburring tool is attached to the robot hand 3 to create a deburring robot. However, various devices such as gripping devices and welding devices can be attached to this hand depending on the purpose of the work.

Next, the wrist portion 5 will be explained with reference to FIGS. 5 to 10. In the deburring robot of this embodiment, when deburring a straight line part, the target workpiece is three-dimensional, and if all corner parts are to be deburred, the degree of freedom is Add two degrees of freedom such as rotation and twist,
It is necessary to have a total of 5 degrees of freedom. This is because 6 degrees of freedom are required to determine the position (including posture) of a rigid body, but since the deburring tool is always rotating (1 degree of freedom), 1 degree of freedom can be removed, so 5 degrees of freedom are required. good. However, the two additional degrees of freedom are the degrees of freedom needed when deciding on a tool that is easy to cut and the posture of the target workpiece before starting the work when it comes to burrs on straight parts. There isn't. For this reason, it is not necessary to stop at all points within the movable range; it is sufficient to be able to stop at the minimum necessary points. Therefore, there is no need to use a servo motor as a drive source for rotation, and a simple mechanism for rotation may be used.

Further, even when used as other linear track work robots, it can be widely used as long as it has the above-mentioned degree of freedom.

FIG. 5 shows the appearance of the wrist portion. Two rotation mechanism parts 16 are attached to the wrist part in order to provide rotational freedom in two directions. The two rotating mechanism parts 16 are integrated by a relay plate 17b, and the relay plate 17a is attached to the plate 15 of the linear motion mechanism part shown in FIG. And a deburring tool 3' is attached. Due to the two degrees of freedom of the wrist, it can take three types of postures, A, B, and C in Figures 6 and 7, and three types of postures, A', D, and E in Figures 8 and 9. I can do things.

Hereinafter, with reference to FIG. 10, the principle of operation of the wrist portion will be explained in detail in correspondence with the postures shown in FIGS. 6 and 9. The drive device in FIG. 10 is shown in an enlarged scale to facilitate explanation of the principle of operation. In this embodiment, an air cylinder is used as the drive source for rotation, but of course other drive sources may be used. The rotational force is obtained by converting the linear motion of the air cylinder into rotational motion using the rack and pinion.

First, in order to create the posture shown in FIG. 6A, air is sent from the rear end of the stopper double-acting cylinder 19a, and the stopper double-acting cylinder 19a moves forward, and the stopper 20a attached to the tip also advances to the rack 21a.
is set on the line of motion. Next, double acting cylinder 2
When air is sent from the rear end of cylinder 2a, the double-acting cylinder 22a moves forward, and the rack 21a attached to the tip moves forward, causing stopper 20a to move forward.
The rack 21a comes to a stop. At this time, since the rack 21a has moved, the pinion 23a
rotates by the amount of movement of the rack 21a, and the wrist assumes posture A.

In posture B, when air is sent from the front of the double-acting stopper cylinder 19a, the double-acting cylinder 19a for the stopper moves backward, and the stopper 20a attached to the tip is removed from the line of motion of the rack 21a.
Next, when air is sent from the rear end of the double-acting cylinder 22a, the double-acting cylinder 22a moves forward, and the rack 21a attached to the tip moves.
a hits the front stopper 24a and stops. Then, the pinion 23 is moved by the stroke of the rack 21a.
a rotates and changes from posture A to posture B.

Posture C is based on the same principle, and the double-acting cylinder 22a is moved backward until the rack 21a hits the rear stopper 25a.

In the posture A' in FIG. 9, as in posture A, the stopper cylinder 19b moves forward, the stopper 20b is set on the line of motion of the rack 21b, and the cylinder 20b moves forward.
2b moves forward and the posture when the rack 21b hits the stopper 20b and stops is posture A'. Posture D is the same as posture B when the rack 21b hits the front stopper 24b and stops, and posture E
In this case, the rack 21b is in the rear stopper 2 as in posture C.
This is the posture when it hits point 5b and stops.

In this way, by using an air cylinder and a simple mechanism, it is possible to have two degrees of freedom, which are sufficient for performing simple tasks such as deburring a straight section.

Next, an elastic body (or elastic mechanism) 3a is provided between the deburring tool 3' and the rotation mechanism section 5 described above. This elastic body (or elastic mechanism) 3a is mounted between a holder holding the deburring tool 3' and a plate connected to the force sensor 18. As a result, when a large force or shocking force is applied to the deburring tool, the applied force is softened and the degree of force applied is controlled so as not to destroy the deburring tool 3', the force sensor 18, and other mechanisms. It can be adjusted.

The force sensor 18 is installed between the rotating mechanism 5 and the deburring tool 3'. By detecting the force applied to the deburring tool 3' during work and controlling the feedback, delicate machining work can be performed. For example, as shown in FIG. 19, when this embodiment is used as a deburring device, the pressing force of the deburring tool 3' (this is referred to as F) will affect the condition of the finished surface after cutting. If the pressing force F changes during cutting, the cut surface becomes rough or uneven. For this reason, as shown in Fig. 19, the force sensor 18
A smooth cutting surface can be obtained by monitoring the current pressing force F at any time and controlling the servo motor of the linear motion mechanism so that cutting can be performed with a constant pressing force. The function of the sensor described above is equivalent to that of a three-degree-of-freedom linear spring mechanism, and can be realized by software.

Furthermore, by using a force sensor, teaching can be simplified. As an example, as shown in FIG. 20, the cutting position (point R) is taught by teaching up to the vicinity of the cutting position (point Q), and the cutting position (point R) is not taught by a human, but from the force sensor 18 from point Q. It automatically approaches while monitoring the applied force, and stops when the force (reaction force received by the force sensor) reaches a preset appropriate range, and sets that as the cutting position (point Q). can. These teaching tasks can now be programmed off-line by installing a force sensor.

Next, a control method for deburring while keeping the pressing force constant and a control method for facilitating teaching will be described in detail below.

FIG. 21 is a hardware configuration diagram of the control device. 16-bit processor i8086 (1 unit) and i8087 (1 unit)
Each unit is connected by a multi-bus, centered around the base. Each motor of the robot is driven by the output of a servo amplifier via a D/A converter, and positional displacement due to rotation of the motor is detected by a rotary encoder and a counter. Additionally, a force sensor attached to the tip of the robot detects the force applied to the robot.

FIG. 22 summarizes the relationship between the robot and the control section. Force and position feedback signals are taken into the control unit by the force sensor and encoder of the robot, and arithmetic processing is performed in the control unit along with the given parameters, and output as a speed command signal to the motor of the robot.

FIG. 23 shows a method of calculating the position of the robot hand (deburring tool) in this embodiment. First, a base coordinate system (fixed) is determined, and the position vector (expressed in the base coordinate system) representing the point where the tool contacts the workpiece is defined as . This is expressed as a three-dimensional vector and is determined by S ₁ , S ₂ , . . . , S ₅ (variables) and the lengths (constants) of each part of the robot. Here, S ₁ , S ₂ , and S ₃ represent translational displacements in the X, Y, and Z axis directions, respectively (these three axes are servo driven) S ₄ , S ₅
indicates rotational displacement as shown in FIG. 25 (these two axes are not servo driven).

Next, a teaching method using the apparatus of this embodiment will be described. As already explained in Figure 20,
Deburring tool 3 up to a certain point (point Q in Figure 20)
The position of is taught by teaching, and from that point onwards, the force sensor is used to automatically move forward, and a point with an appropriate pressing force is determined (point R in Fig. 20). This method will be explained below from the viewpoint of control.

FIG. 24 shows an outline of teaching. First, determine the appropriate position and posture of the tool (the point at which it should contact the workpiece), and then
(determined by S ₁ to _{S 5} in the figure and the dimensions of each part) is determined.

Determine the target value _r to which the next step should be taken.

= [M] ^-1 ∫ (- [K] Δ- [C]) dt……(1
) ΔX= _−r From equation (1), determine the speed that the tool should take. Here, f: External force applied to the tool (detected by the force sensor) ΔX: p- _pr v: Seal speed 3-dimensional vectors [M], [K], [C]: Define the motion characteristics of the tool The matrix is a 3-by-3 matrix of virtual quantities, virtual spring constants, and virtual viscosity coefficients, which are parameters on the control unit software.

The above calculation is actually performed by a computer, and determines the speed _o (n indicates the value at the n-th sampling time) that the robot tool should take at each sampling time. This can be expressed using the following formula: _o = Δt[M] ^-1 ( _o-1 - [K] Δ _o-1 ) + ([I] - Δt[M] ^-1 [C]) _o-1 ... (2) Putting this together, _o = ([A′] _o-1 − [B′] Δ _o-1 ) + [C′] _o-1 ...(3) (here [A′], [ B'], [C'] are [M], [K]
,
A matrix of 3 rows and 3 columns determined by [C]. ) Therefore, the command speed _o is determined from (3).

Here, _o-1 is the force before one sampling (the force applied in each direction of the X, Y, and Z axes is detected by the force sensor), and Δ _o-1 (= _o-1 − _{r,o -1} )
is the difference between the current value _o-1 of the tool one sampling ago and the target value _r,o-1 , and _o-1 is the command speed one sampling ago. In other words, if the tool is not in contact with anything (if no external force is applied)
By changing p _r one after another like _r1 and _r2 in Fig. 24, it is possible to change the tool in a manner that follows _r . Furthermore, _r
Assume that the tool advances and enters the workpiece, for example as shown at _r,3 in Fig. 24, and the tool can only catch up to _{point 3} and then comes into contact with the workpiece (that is, the force sensor detects an external force), then Δ The tool stands still while being pressed with a force corresponding to (the difference between the tool's current value and target value). The force at this time is determined by equation (4) calculated from equation (3).

[A'] - [B'] Δ=0 ...(4) Δ=- _r In other words, the pressing force of the tool against the workpiece is set to a certain value.
If you want to set it to ₀ , you can set _r so that the right side of the following equation (5) calculated from equation (4) becomes ₀ .

₀ = [A′] ^-1 [B′] (− _r ) ...(5) In this way, by changing _r on the software, the tool moves, contacts the workpiece, and When _r is stopped at the point where the force becomes ₀ , that position _r is determined as a teaching point with a certain pressing force of ₀ . Assume that an appropriate teaching point _r,4 (Fig. 24) is determined as described above.

Next, considering that this _r,4 corresponds to _r,10 in Fig. 25, _{the r,11} , _r,12 ,... required for deburring are as shown in Fig. 24. , it is not necessary to bring the tool into contact with the work each time. Since the outline of the workpiece is known in advance, _r,10 , _r,11 , etc. can be determined based on the outline. This becomes the route of _r .

Next, when _r is actually moved on the path of this _r and deburring is performed, the tool moves along the contour of the tool, but it moves in accordance with the irregularities of the contour. The pressing force of the tool changes due to this unevenness, but by keeping the change in the unevenness within a certain range, the pressing force determined in Fig. 24 can be reduced _{to 0.}
can also be kept within a certain range as shown in the following equation (6): ₀ − α≦ ₀ ≦ ₀ + α (6).

In this way, deburring work can be performed while maintaining a substantially constant pressing force.

Next, the positioner 6 having one remaining degree of freedom will be explained with reference to FIGS. 11 to 14. 11th
The figure shows the appearance of the positioner 6. The positioner 6
As shown in Fig. 12, the structure is simple enough to stop at only three locations within the operating range. In order to further facilitate control, an air cylinder is used as the drive source for rotation. The operating principle will be explained with reference to FIG. In order to create the posture F shown in FIG. 12, the stopper cylinder 26 moves forward and the stopper 27 is pushed out onto the line of motion of the rack 29. Then, the cylinder 28 moves forward and the rack 29 hits the stopper 27 and stops. The stroke of the rack up to this point is converted into rotational motion by the pinion 30, and this rotation is transmitted to the base rotating gear 33 via the miter gear 31 and the gear 32.
In the case of posture G, the stopper cylinder 26 moves backward, so that the stopper 27 is removed from the line of motion of the rack 29. Then, the cylinder 28 advances and the rack 29 hits the front stopper 34 and stops, and the pinion 30 rotates by the stroke of the rack 29, changing from the posture F to the posture G. In the case of posture H, the rack 29 changes to this posture by moving backward until it hits the rear stopper 35 and stops.

Next, the target component gripping mechanism will be explained with reference to FIG. 14. The gripping mechanism is fixed on a base 36 that is attached to a base rotation gear 33.
The mechanism is such that the target part is sandwiched between a fixed block 37 and a moving block 38 and fixed. A mount 40 is attached to the tip of the air cylinder 39, and the mount 40 and link 42 are attached with a pin 41, and the link 42 and the moving block 38 are attached.
It is also attached with pin 41. Since the center portion of the link 42 is attached to the base 36 with a pin 41, when the air cylinder 39 moves forward, the mount 40
begins to move in the direction of the arrow, and the direction of movement is reversed at the pin 41 in the center of the link 42, and the moving block 3
8 starts to move in the direction of tightening the parts.

As described above, this embodiment has three degrees of freedom in which the position and orientation can be controlled by the servo motor, and although complex and versatile movement is not possible, it is possible to perform the minimum necessary positioning, control and position, By combining this with three degrees of freedom, which makes it easy to control the posture, it is possible to deburr most straight sections, as shown in FIGS. 15 to 18. Furthermore, the linear trajectory accuracy is good, teaching and control are easy, and the structure is simple, so it can be an inexpensive device.

It should be noted that, as a matter of course, the present invention is not limited only to the above embodiments.

〔Effect of the invention〕

The present invention uses the device as a first detection means, a force sensor, which detects the external force applied to the tool between the 3-axis linear motion part and the hand, and a force sensor that detects the deviation between the actual position of the robot hand and a target value. By providing a position sensor as the second detection means and a calculation means for calculating the tool feed rate from the viscosity constant, spring constant, first detection result, and second detection result, during teaching, Once the viscosity constant and spring constant are determined, if the deviation between the target value and the actual tool becomes large,
Cutting with a large force and when the deviation becomes small, the tool feed rate is determined so that the tool cuts with a small force.If the outline is known in advance based on the teaching point, the tool path can be automatically determined. Determine exactly.

Furthermore, even if the shape of the burr exceeds a certain range and a force exceeding a certain level is applied to the tool, damage to the tool and the workpiece can be prevented.

Furthermore, the present invention can increase rigidity by employing a three-axis linear motion mechanism, thereby enabling highly accurate positioning.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view of the embodiment, and FIG. 2 is a perspective view showing only the X-axis of the linear motion mechanism.
3 and 4 are perspective views showing a conventional deburring system. 5 is a perspective view of the wrist of the robot, FIG. 6 is a front view showing the movable range of the wrist of the robot, and FIG. 7 is a side view of the wrist of the robot. The figure is a front view of the robot's wrist, FIG. 9 is a side view showing the movable range of the robot's wrist, and FIG. 10 is a perspective view for explaining the operating principle of the robot's wrist. . FIG. 11 is a perspective view showing the positioner, FIG. 12 is a side view showing the movable range of the positioner, FIG. 13 is a perspective view for explaining the operating principle of the positioner, and FIG. 14 is a perspective view showing the positioner's movable range. FIG. 2 is a perspective view showing a target component gripping mechanism. Figures 15 to 16
The drawings and FIG. 18 are side views showing deburring of a rail-shaped component in the example, and FIG. 17 is a front view thereof. FIG. 19 is a side view showing the deburring state, and FIG. 20 is a side view illustrating the teaching work. FIG. 21 is a hardware configuration diagram of the control device, FIG. 22 is a relationship diagram between the robot and the control section, and FIG. 23 is an explanatory diagram showing a method for calculating the position of the robot hand. 2
Figure 4 shows an overview of teaching.
FIG. 25 is a diagram showing the state of deburring. 3... Robot hand, 3'... Deburring tool,
4...Linear motion mechanism section, 5...Wrist section, 6...Positioner, 7...Servo motor, 16...Rotation mechanism section, 18...Force sensor.

Claims (1)

[Scope of Claims] 1. A deburring tool is supported at the tip of a servo-driven three-degree-of-freedom linear motion mechanism via a first detection means for detecting force and a robot hand, and the tool is attached to a target object. A deburring robot device that continuously cuts off burrs generated on the object by tracing the object, the device comprising: a second detection means for detecting the position of the robot hand; a robot hand; A matrix that defines the motion characteristics of the tool, that is, a virtual mass, a virtual spring constant, and a virtual viscosity constant, is given to the control unit that controls the tool, and each of the above constants,
and the detection result of the first detection means, and the second
1. A deburring robot apparatus comprising a calculation means for calculating the moving speed of the robot based on the deviation between the actual position of the robot hand and a target value determined by the detection means.