CA2071162A1

CA2071162A1 - Automatic control system for task-performing device

Info

Publication number: CA2071162A1
Application number: CA002071162A
Authority: CA
Inventors: Mark Janusz
Original assignee: Compustrip Systems Ltd
Current assignee: Compustrip Systems Ltd
Priority date: 1992-06-12
Filing date: 1992-06-12
Publication date: 1993-12-13

Abstract

AUTOMATIC CONTROL SYSTEM FOR
TASK-PERFORMING DEVICE

ABSTRACT

An automatic control system for controlling the position and orientation of a task-performing device, such as a closed-cycdle paint stripping head, relative to an irregular surface area, such as a fuselage of an aircraft, as the device is displaced over the overface.
The control system comprises a support for the task-performing device secured to a boom having articulated couplings to displace the boom on at least two trans-verse pivot connections to orient same relative to the support as the device is displaced over the irregular surface area. Sensors are integrated in connectors for the head to sense the relative position of the support, and to transmit information signals indicative thereof to a control device which, in turn, generates control signals to motors to actuate the displacement of the boom to maintain the support in constant relationship to the boom area regardless of changes in the orienta-tion or shape of the surface area over which the tool is being displaced.

Description

TECHNICAL FIELD
The present invention relates to an automatic control system for controlling the position and orien~
tation of a task-performing device relative to a surface area, and more particularly, but not exclu-sively, to a task-performing device which is an automatic dry stripping head secured to a robotic arm to strip paint from the fuselage of an aircraft.

BACKGROUND ART
In my earlier U.S. patent application Serial No.
693,613 allowed on February 11, 1992 and issued under U.S. Patent No. on 1992, there is described a positioning apparatus for supporting and guiding a paint stripping tool over a surface area of an aircraft fuselage. The present invention relates to improvements in the stripping head and to the automatic control system for controlling the position and orientation of the head as it is displaced relative to the surface area to be stripped.

, . , SUMMARY OF INVENTION
It is a feature of the present invention to there-fore provide an automatic control system for control-ling the position and orientation of a task-performing device relative to a surface, and incorporating improved sensing means and a control system capable of maintaining the task-performing device constantly re-oriented relative to the surface where a task is to be performed.
Another feature of the present invention is to provide an automatic control system for controlling the position and orientation of an automatic paint strip-....
ping head secured to and displaced by a robotic arm ~i relative to a surface of an aircraft fuselage where ;;' : . ` .
~, paint is to be stripped and wherein the head is maintained in constant pressure contact with the surface area regardless of changes in the shape or direction/orientation of the surface.
According to the above features, from a broad aspect, the present invention provides an automatic control system for controlling the position and orien-tation of a task-performing device relative to a surface as the device is displaced. The control system comprises a support for the task-performing device.
The support is secured to articulation means to line same displaceably, on a-t least traverse pivot connec-tions, to a tool positioner by automated control and activation means relative to the support following a change in position or orientation of the support during its displacement over the surface.
According to another aspect of the present invention the control system controls the position and orientation of an automatic paint stripping head secured to a robotic arm and wherein the displaceable frame forms part of the head, and has a working opening with a seal about the opening. The information signals provide for the control means to maintain the seal in constant contact with the surface area at substantially constant pressure regardless of changes in the shape or orientation of the surface as the head is displaced over same.

BRIEF DESCRIPTION OF DRAWINGS
A preferred embodiment of the present invention will now be described with reference to the accompany-ng drawings, in which:

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;, FIGURE 1 is a perspective view of a positioning apparatus of the prior art for positioning a dry abrasive paint stripping tool to effectuate a work function on a predetermined area of an aircraft fuselage;
FIGURE 2 is a perspective view showing the construction of the dry stripping head of the present invention secured to the robotic arm of the positioning apparatus of Figure l;
FIGURE 3 is a perspective view, similar to Figure

2, but taken from the opposed side of the stripping head;
FIGURE 4 is a side view showing the construction of a first connector having a position detector for sensing and displacing the head along a first axis;
FIGURE 5 is a side view of Figure 4, but showing a second position detector for detecting and controlling the position of the head along a transverse axis to that of Figure 4;
FIGURE 6 is a perspective view showing the dry stripping head in contact with an irregular fuselage surface area being stripped of paint; and FIGURE 7 is a simplified schematic diagram showing the connection of the control computer with respect to the sensors and the orientation of the stripping head;
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BRIEF DESCRIPTION OF DRAWINGS
Referring now to the drawings, and more particu-larly to Figure 1, there is shown generally at 10 a positioning apparatus of the prior art to support a guided tool 11, herein a dry abrasive paint stripping tool, to strip paint from a surface area 12 on the fuselage 13 of an aircraft 14. A support guide frame 15 is displaceably connected to a mobile base 16 which is displaceable on a floor by motorized wheels 17. A
pair of parallel vertical posts 18 are secured in , .
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aligned relationship and extend from the displaceable base to support the guide frame 15. The guide frame 15 is secured to the vertical post by pivotal telescopic couplings 19 which are displaced along the post by a displaceable connection, such as a chain link 20, which is motor-driven by the motors 21 secured to the top end of the vertical post 18. A transverse guide beam 24 is secured to the front end of the side arms 23 through an axial connection to permit axial displacement of the guide beam when the side arms are offset from a common horizontal plane. A telescopic support arm 25 is secured to a carriage 26 which is motor-driven and displaced along the transverse guide beam 24. The present invention is concerned with a task-performing .

devlce, such as the automatic dry stripping head 11 secured to the telescopic support arm 25 and to the automatic control system for controlling its position and orientation.
Referring now to Figure 2 there is shown the automatic dry stripping head 11 of the present invention secured to the robotic arm, herein the telescopic support arm 25, through an articulation ; connection 30. A support in the form of a displaceable frame 31 defines a working opening 32 for the head 11 : towards which abrasive particles are directed by the blasting nozzles 33 which are secured to the housing 34 and extend in an entry port 35 thereof. An exhaust duct 36 evacuates the particles of abrasive, herein dry particles, as well as the particles of paint which are , stripped from the surface 12 of the aircraft fuselage by impingement. A video camera 37 is also positioned in the entry port 35 of the housing 34 to monitor the stripping action. A light 38 provides proper lighting :
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within the housing head and in the direction of the working opening 32. The support arm 25 and the articu-lation connection 30 cons-titutes a positioner for the : , frame 31 or tool.
As herein shown, a flexible seal in the form of . flexible bristle fibers 39 extends around the working ~ opening 32 and is secured to the displaceable frame 31 - and prevents the abrasive particles as well as the paint particles from being ejected outside the head 11.
The bristles 39 also permits the passage of some outside air therethrough in the direction of the working opening. A flexible side wall 40 is connected , .
between the frame 31 and the blasting housing 34.
The displaceable frame 31 is connected to the housing 34 through a pair of connectors 41 provided on both sides of the frame 31. Each of these connectors are provided with a position sensing potentiometer 42 which has a pinion gear 43 connected to the shaft 44 thereof and gear-coupled to a toothed segmented element 45. Each of these opposed connectors 41 are comprised of an arm 46 affixed to the displaceable frame 31 and pivotally connected to a fixed arm 47 which is connected to the housing 34. The arm 46 also has an extension section 48 at the free end of which is secured a tension spring 49. The other end of the tension spring is secured to the housing 34. This spring biases the displaceable frame 31 outwardly of the housing 34 when the seal 39 is not in abutment with any surface to be worked. Also, in this position, the flexible side wall 40 is fully extended. The potentio-meter 42 also provides a reference signal in this inactive position of the head. The connector on the other side is positioned on a common axis and operates in the same manner as the one just described. These ;' : ~:

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potentiometers 42 therefore provide information signals to a computer control device, as shown in Figure 7, to indicate the displacement of the frame 31 along a first axis, independently for each side .
As shown in Figure 5 one of the connectors 41 is further provided with a second position detector which is comprised of a further toothed segmented element 50 which is secured to an arm 51 and also secured to the displaceable frame 31. When the frame 31 is displaced in a direction opposite to the first axis of displace-ment as sensed by the potentiometers 42, namely in the direction indicated by arrows 52, the toothed segmented element 50 is caused to rotate about its fixed connec-tion with the arm 51 thereby causing a rotational displacement of the pinion gear 53 of a still further potentiometer 54 which sends a signal to the control computer device of Figure 7. The potentiometers 54 are also secured to a bracket 55 attached to the housing 34. Accordingly, these potentiometers can sense the articulation of the displaceable frame 31 and its flexible seal 39 along two transverse axes.
It is also pointed out that during initial contact of the seal 39 with the surface area 12, the telescopic support arm 25 is advanced to exert a pressure between the seal 39 and the surface 12, and this pressure is maintained throughout the operating cycle of the dry stripping head. The initial pressure is sensed by the potentiometer 54 which provides information signals that can be considered by the computer 70 to be reference signals whereas to sense any further changes therefrom during operation.
As shown in Figure 3 a contact sensor in the form of a measuring wheel 56 is automatically actuated at the end by the motor 57 which receives signals from the control computer 70 (see Figure 7), to move the track-ing wheel 56 forwardly to engage the working surface 12 ~ .

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prior to the displacement of the blasting housing 34 upward or downward by the motors 62 that actuates the housing support arm 34 vertically respective to the transverse cam. The length of this vertical displace-ment is always preprogrammed. This wheel 56 monitors the actual vertical displacement on the aircraft surEace and feeds this information to the motion-control computer. After the preprogrammed vertical displacement has been completed the tracking wheel is automatically retracted before the next horizontal displacement is initiated. Other measurement means can be conceived to effectuate this measurement.
Referring now again to Figures 2 and 6, there is shown the construction of the articulated connection 30, and it is comprised of a first and second motor-driven pivot connection 60 and 61, well known in the art. These pivot connections are controlled by motors to displace the head 11 along two transverse axes with respect to the telescopic support arm 25.
As shown in Figure 7, the signals from the sensors 42 are fed to the control computer through connections 42' and 42" while the signal from the other potentio-meter 54 is sent to the control computer through connection 54'. These information signals indicate to the computer the position of the displaceable frame relative to the housing 34 and the control computer 70 generates control signals at its outputs to control the motor 62 in response to the signals on inputs 42' and 42" and the motor 63 in response to the signal on the input 54' to displace the first and second pivot connections 60 and 61 to realign the housing 34. The control computer also senses if a change in pressure has taken place between the seal 39 and the surface area 12, and therefore it also controls the motor 64 ~:

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which is coupled to the telescopic support arm 25 to displace same forwardly or rearwardly to increase or decrease the pressure of the head on the working surface.
It is within the ambit of the present invention to cover any obvious modifications of the preferred embodiment described herein, provided such modifica-tions fall within the scope of the appended claims.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An automatic control system for controlling the position and orientation of a task-performing device as it is displaced relative to a surface area, said control system comprising a support for said task performing device, said support being secured to articulation means to link said support displaceably on at least transverse pivot connections to a positioner, said positioner being repositioned by automated control and actuation means relative to said support following a change in position or orientation of said support during displacement thereof over said surface area.

2. An automatic control system as claimed in claim 1 wherein said transverse pivot connections are provided with sensing means for sensing the changes in position of said support and transmitting information signals indicative thereof to said automated control and actuation means.

3. An automatic control system as claimed in claim 2 wherein said task performing device is an automatic paint stripping head secured to a robotic arm.

4. An automatic control system as claimed in claim 3 wherein said support is a chamber comprising a displaceable frame defining a working opening, a flexible seal about said opening, and a flexible side wall is connected between said frame to a blasting housing in which is located one or more blasting jets and an outlet vacuum port to evacuate abrassive substance and paint particles from said housing.

5. An automatic control system as claimed in claim 4 wherein said sensing means comprises a pair of spaced apart connectors secured to said displaceable frame, said connectors each having first position detectors to detect the position of said frame relative to a common axis, one of said pair of detectors further having a second position detector to detect the angular position of said frame along a transverse axis to said common axis, said information signals providing for said control and actuation means to maintain said flexible seal in constant contact with said surface area at substantially constant pressure regardless of changes in the shape of said surface area.

6. An automatic control system as claimed in claim 5 wherein said connectors are spring biased connectors applying outward pressure to said frame to maintain said frame in an initial plane and said flexible side wall taut in the absence of displacement of said frame by pressure contact of said seal with an surface area.

7. An automatic control system as claimed in claim 6 wherein said first position detectors comprise a toothed segment secured to an arm fixed to said displaceable frame, said arm being pivotally secured to a pivot connection, said toothed segment being in toothed engagement with a pinion gear secured to a shaft of a transducer element to translate said rotation of shaft into said information signals when said pinion gear is rotated due to the displacement of said arm caused by movement of said displaceable frame along a first plane.

8. An automatic control system as claimed in claim 7 wherein said transducer element is a variable resis-tance potentiometer providing a variable electrical signal to said control means.

9. An automatic control system as claimed in claim 6 wherein said second position detector comprises a second toothed segment secured to said displaceable frame, a pinion gear secured to a shaft of a further transducer element in toothed contact with said second toothed segment, said second toothed segment being displaced by movement of said displaceable frame along a second plane.

10. An automatic control system as claimed in claim 7 wherein said arm has a free end thereof connected to a tension spring constituting a spring bias to apply said outward pressure to said frame, said flexible side wall being a tubular jacket of flexible material and secured at one end about said opening of said displaceable frame and at an opposed end about an opening in said blasting housing.

11. An automatic control system as claimed in claim 7 wherein said flexible seal is comprised of a brush-like annular seal formed from bristles of flexible material.

12. An automatic control system as claimed in claim 2 wherein said positioner is comprised of a telescopic support arm having an articulating connection secured to said support with said arm and articulating connec-tion being displaced by motors constituting said actuation means, said automated control being a control computer.