Patent Application
20090192644
The present invention relates to a method and system for manufacturing an article, and, more particularly, to a method and system for avoiding mistakes using portable hand-tools during manufacture an article.
During the manufacture of an article, it is often necessary for a worker to use a hand-held tool to carry out various manufacturing steps, such as assembling, welding, painting, etc. The article may be in the form of an assembly or sub-assembly such as a transmission, machine frame, operator's cab, electronic packaging, etc.
In the manufacturing environment, a worker using a hand-held tool cannot consistently duplicate exact work from one assembly to another assembly. For example, assembly lines often require many threaded fasteners to be assembled using a torque gun at a single workstation. Known control systems can count the number of times the torque gun reaches the required torque value, but cannot determine if all the fasteners were tightened, or if some were tightened twice, or if the fasteners were tightened in a specific sequence.
What is needed in the art is a method and system which not only can determine whether a particular manufacturing task is carried out, but also determine whether the manufacturing task was carried out at the correct location and/or in the correct sequence.
The invention in one form is directed to a method of manufacturing an article, including the steps of: establishing a defined location for a tool activity to occur; determining an actual location of the tool; comparing the actual location of the tool with the defined location; ascertaining an occurrence of the tool activity at the actual location; and verifying whether the tool activity occurred at the defined location.
The invention in another form is directed to a system for manufacturing an article, including a tool for carrying out a tool activity on the article, a memory storing a defined location for the tool activity to occur, a location detector for detecting an actual location of the tool, and an electrical processor in communication with the memory and the location detector. The electrical processor is configured for comparing the actual location of the tool with the defined location, ascertaining an occurrence of the tool activity at the actual location; and verifying whether the tool activity occurred at the defined location.
Referring now to the drawings, and more particularly to
For a given manufacturing process, article 12 is assumed to have a number of defined locations 14 corresponding to tool activities to be carried out using tool 16. In the embodiment shown in
As indicated above, tool 16 is assumed to be a torque gun in the embodiment shown in
Tool 16 could also take the form of other types of portable hand-held tools, such as a torque wrench, weld gun, paint gun, pulse gun, air tool or banding tool.
Tool 16 also includes one or more optical targets 22 which are placed at corresponding exterior locations. In the embodiment shown, tool 16 includes a single optical target in the form of an active target which emanates a particular type of light. Rather than being an active target requiring a source of electrical power (e.g., battery power), it is also possible that target 22 could be a passive target such as a number of reflective balls, a reflective strip, a projection with a predefined shape, etc.
An electrical circuit 24 includes an electrical processor 26, memory 28, one or more cameras 30, and feedback 31. Electrical processor 26 preferably is a microprocessor which is coupled with each of memory 28 and camera(s) 30. Electrical processor 26 is hardwired with each of memory 28 and camera 30 in the illustrated embodiment, but could also be coupled via wireless connections, etc.
Memory 28 is any suitable type of memory capable of long term storage of data which is provided to electrical processor 26. For example, memory 28 can be used to store the coordinates of defined locations 14 on article 12.
Camera 30 is used to detect the actual location of optical target 22 on tool 16, and provides corresponding output signals to electrical processor 26. In the embodiment shown, camera 30 is assumed to be an infrared (IR) camera which detects light which is transmitted from optical target 22. Preferably multiple cameras are used at different locations associate with the work station at which article 12 is located so that optical target 22 may be more accurately located relative to a known coordinate.
Feedback 31 is a schematic representation of some type of feedback which is provided to an operator or assembler during the manufacturing process, discussed in more detail below.
Referring now to
In the embodiment shown, a three-dimensional representation of article 12 is generated and stored within a computer aided drafting (CAD) library within memory 28. Each defined location 14 is correlated to a corresponding point on the three-dimensional representation of article 12. The three-dimensional coordinate of each correlated point is likewise stored in memory 28. Additionally, a defined tool activity is assigned for each correlated point on the three-dimensional representation of article 12. The assigned tool activities for each correlated point are likewise stored in memory 28. Thus, the defined locations 14 in essence overlie the three-dimensional representation of article 12, and each defined location has a corresponding defined tool activity.
Rather than using a CAD library or numerical analysis technique to establish the defined locations 14 for a tool activity, it is also possible to empirically establish the defined locations 14. In particular, the position(s) of tool 16 may be tracked during an initial data gathering stage and correlated with the occurrence of tool activities to establish the defined locations 14 which are stored within memory 28. In the case of a moving tool activity such as welding or painting, a set of detected defined locations 14 can be used to define the tool activity.
Electrical processor 26 uses the output signals from camera 30 to determine the actual location of tool 16 (block 42). The actual location is compared with a corresponding defined location for a given tool activity (block 44). Electrical processor 26 then ascertains whether the prescribed tool activity occurred at the actual location (block 46). For example, in the case of a torque gun, it is possible to sense whether the torque which is applied to the head of the bolt reaches a predefined torque value. This information can be sent via a wired or wireless connection to electrical processor 26. The prescribed tool activity must occur, and the actual location must match with the defined location, in order for the tool activity to be verified (block 48).
At decision block 50, a determination is made as to whether an operator is to be provided with feedback in the event that the manufacturing process is not proceeding as expected. More particularly, if the tool activity does not correspond to the prescribed tool activity, and the actual location does not match with the defined location, then an operator is provided with feedback (block 52). For example, electrical processor 26 can control the manufacturing process to shut off tool 16, not allow article 12 to advance to a next workstation, trigger a warning light observable by the operator and/or generate a written report. The feedback can be positive or negative. For instance, a monitor can be placed in front of an operator with a model of the assembly that has components turning a different color when the activity is completed on that component. This gives the operator visual feedback on what is left to complete, or shows what is next in the sequence if a sequence is required. Other types of feedback are of course also possible.
On the other hand, if the tool activity does correspond to the expected tool activity, and the actual location matches with the defined location, then there is no need to provide feedback to an operator (line 54).
At decision block 56, a determination is made as to whether tool 16 should be moved to additional defined locations 14 for further tool activities. If so, then control loops to block 42 and the control logic repeats. On the other hand, if there is only a single defined location for a tool activity, or tool 16 is at the defined location corresponding to a last tool activity, then the control logic simply ends.
For an article having multiple defined locations with corresponding tool activities at each defined location, it is possible to track the actual locations and/or tool activities at each actual location for various purposes. For example, one purpose for tracking the actual locations and tool activities at each actual location is to identify the particular article 12 which is being manufactured. This allows electrical processor 26 to know the sequence of the remaining defined locations and corresponding tool activities which are to occur after the article 12 is identified. If an operator does not perform a next expected tool activity for a given article 12, then feedback may be provided to the operator at block 52.
From the foregoing description, it is apparent that the method and system of the present invention dynamically avoids mistakes during the manufacturing process by tracking the position and operation of tool 16 relative to a predetermined or dynamically identified article 12.
In the system 10 for manufacturing an article described above, a location detector detects the position of tool 16 using camera 30 and optical target 22. Optical target 22 thus in essence is a passive component, the position of which is sensed using one or more cameras 30. Cameras 30 are therefore the active components providing output signals to electrical processor 26. It is also possible to configure system 10 with a location detector having an active component on tool 16 which provides an output signal to electrical processor 26 to determine the actual location of tool 16. For example, tool 16 may include a location detector in the form of an active sensor which senses its position relative to a fixed coordinate and transmits a wireless signal to electrical processor 26.
