Computer implemented method, and apparatus for controlling a hand-held tool

• US 5,903,462 A
• Filed: 10/17/1997
• Issued: 05/11/1999
• Est. Priority Date: 10/17/1996
• Status: Expired due to Fees

• Current Assignee: National Aeronautics and Space Administration US Government As Represented By The Administrator of The
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Wagner, Kenneth William, Taylor, James Clayton
• Primary Examiner(s): Gordon, Paul P.
• Assistant Examiner(s): Rao, Sheela S.
• Application Number:
  US08/954,055
• Time in Patent Office: 571 Days
• Field of Search: 364/474.1, 318/490, 318/434, 318/571, 340/680, 433/114, 81/487, 144/48.5, 144/104, 254/209, 254/248, 381/31, 137/557
• US Class Current: 700/168
• CPC Class Codes: B25B 21/00 Portable power-driven screw or nut setting or loosening tools; details or components, e.g. casings, bodies, of portable power-driven tools not particularly related to the operation performed B25F5/00; for mounting or dismounting wheels B60B29/006; Attachments for drilling apparatus serving the same purpose machines B23P19/06
• CPC Class Codes: B25B 23/147 specially adapted for electrically operated wrenches or screwdrivers
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: B64G 4/00 Tools specially adapted for use in space
• CPC Class Codes: G05D 17/02 characterised by the use of electric means

Abstract

The invention described here in is a computer-implemented method and apparatus for controlling a hand-held tool. In particular, the control of a hand held tool is for the purpose of controlling the speed of a fastener interface mechanism and the torque applied to fasteners by the fastener interface mechanism of the hand-held tool and monitoring the operating parameters of the tool. The control is embodied in intool software embedded on a processor within the tool which also communicates with remote software. An operator can run the tool, or through the interaction of both software, operate the tool from a remote location, analyze data from a performance history recorded by the tool, and select various torque and speed parameters for each fastener.

Claims

1. An apparatus for controlling and diagnosing torque and speed applied to fasteners by a hand-held tool comprising:

a housing having a hand-grip portion;

contained within said housing, an electric motor having a shaft, said motor being operable in current mode to control a force to be applied to a fastener interface mechanism connected to the shaft by varying current through the windings;

a processor contained within said housing having a clock for providing timing pulses, wherein said processor controls an interrupt driven state machine for monitoring operating parameters of the hand-held tool, keeping a performance history of the tool'"'"'s operation comprising performance records, communicating with a remote computer and controlling the torque and speed applied to fasteners;

a nonvolatile, writable memory for storing performance history;

two random access memory locations for storing data points;

a separate memory location for storing said data points into performance records from which the performance history will be selected;

a first communications port located the housing capable of being accessed from exterior portion of the housing by the remote computer for linking said processor with the remote computer;

a torque transducer responsive to the force being applied to the fastener interface mechanism by the shaft of the electric motor having an output capable of being transferred as a digital value to the processor;

temperature transducers located within said housing having outputs capable of being transferred as digital values to the processor;

said remote computer comprising a second communications port for uploading and downloading data to the hand-held tool and a graphical user interface for allowing an operator to manipulate the data and remotely control the tool;

a circuit breaker connected to said motor for controlling current to the motor;

display indicators located on the exterior of the housing for communicating information to the operator in response to messages generated by the processor;

a trigger located on the exterior of the housing for switching the tool between a running state and an idling state and for sending a signal to the processor for the purpose of alerting the processor as to whether the tool is in a running or idling state; and

selection controls located on the exterior of the housing for an operator to select torque and speed parameters.

2. The apparatus of claim 1 wherein each of said performance records contains calculated torque, calculated turns count, and time for calculated torques that exceed the torque threshold for the fastener.

3. The apparatus of claim 2 wherein said nonvolatile, writable memory for storing said performance history is a radiation tolerant EEPROM capable of being spaceflight qualified.

4. The apparatus of claim 3 wherein said selection controls comprise controls for selecting between ratchet and motorized operation of the tool, selecting a speed direction and revolution per minute value for operation of the tool;

and for selecting several combinations of torque and a number of revolutions to be applied or degree angle not to be exceeded.

5. The apparatus of claim 4 wherein said display indicators comprise

an alphnumeric display located externally on said housing for displaying various parameter values and messages to the operator;

and

indicator lights located on the exterior of the housing to alert the operator to various conditions of the tool'"'"'s operation.

6. A computer-implemented method for controlling and diagnosing torque and speed applied to fasteners by a hand-held tool and for monitoring operating parameters of the tool, comprising the steps of:

(a) monitoring the operating parameters of the hand-held tool comprising a housing with a hand-grip portion, an electric motor contained within said housing having a shaft, said motor being operable in current mode to control a force to be applied to a fastener interface mechanism connected to the shaft by varying current through the windings, a power supply for driving said motor and a circuit breaker for controlling the current to the motor;

(b) creating a performance history of the tool'"'"'s operation comprising performance records to be stored in a nonvolatile, writable memory;

(c) controlling the torque and speed applied to fasteners by a program controlled processor having a clock for generating timing pulses and a first communications port for linking to a remote computer;

(d) providing a remote computer with a graphical user interface for analyzing at the remote computer torque, speed and parameter information;

(e) remotely directing the torque and speed to be applied to each of said fasteners by the hand held tool under the control of the remote computer.

7. The method of claim 6 wherein said operating parameters comprise temperatures, a motor current level, a power supply voltage level, and integrity of the nonvolatile memory containing a computer program and data.

8. The method of claim 7 wherein monitoring the operating parameters comprising temperatures, a motor current level, and a power supply voltage level comprises the following substeps of step (a):

(a1) upon a periodic timing pulse from said clock, said processor receiving digital values of the operating parameters that have been stored in a memory location of a random access memory;

(a2) determining whether the digital value is within an accepted tolerance range stored in a nonvolatile memory;

(a3) obtaining an indication of the integrity of the computer code and data stored in the nonvolatile, writable memory; and

(a4) storing the digital value and the indication of substep (a3) in a performance record stored in the random access memory.

9. The method of claim 8 wherein said digital value is not within the accepted tolerance range so that step (a) further comprises the following substeps:

(a5) illuminating a fault indicator light located on the exterior of the housing;

(a6) displaying a message on an alphanumeric display located on the exterior of the housing for alerting the operator one of the operating parameters is not within its accepted tolerance range; and

(a7) putting the tool in an appropriate safe state.

10. The method of claim 9 further comprising the following substeps:

(a8) upon a periodic timing pulse from said clock, said processor receiving digital values of the operating parameters that have been stored in a memory location of a random access memory;

(a9) determining whether the digital value is within an accepted tolerance range stored in a nonvolatile memory; and

(a10) removing the tool from the appropriate safe state.

11. The method of claim 7 wherein monitoring the operating parameter of the integrity of the nonvolatile memory containing a computer program and data comprises the following substeps of step (a):

repeatedly performing a checksum calculation test on the nonvolatile memory; and

resetting unused memory with single-byte opcodes.

12. The method of claim 11 wherein substep (a3) further comprises the substep of:

entering a self test fail state upon failure of the checksum test which may only be exited upon cycling power to the tool.

13. The method of claim 11 wherein substep (a3) further comprises the substep of:

returning to an idling state upon success of the checksum test.

14. The method of claim 6 wherein step (c) comprises the following substeps:

(c1) sending a communication signal from second communications port of the remote computer to the first communications port of the processor signifying that the remote computer seeks to download data to the nonvolatile, writable memory of the hand-held tool;

(c2) sending a ready signal from the first communications port of the processor to the second communications port of the remote computer;

(c3) upon receipt of the ready signal, transmitting from a permanent memory of the remote computer to the nonvolatile, writable memory of the hand-held tool programmed torque, the torque threshold, torque angle, turns count and turns count direction for each fastener.

15. The method of claim 14 further comprising the following substeps:

(c4) said processor receiving a signal that the tool is in a running state from a trigger located on the exterior of the housing for switching the tool between a running state and an idling state;

(c5) receiving a digital value representing a torque value sensed by a torque transducer responsive to the force being applied to a fastener interface mechanism by the shaft of the electric motor having an output capable of being transferred as a digital value to the processor;

(c6) said processor calculating an actual torque using the digital value;

(c7) said processor calculating the turns count achieved since the tool entered a running state based on a boxcar averaging algorithm of a number of motor shaft turns represented by a finite number of digital electronic pulses generated by electronics connected to the motor'"'"'s shaft;

(c7a) said processor incrementing a total turns count since the tool was assembled;

(c8) comparing calculated torque to the programmed torque;

(c9) saving to next empty performance record in the random access memory the calculated torque, calculated turns count, and time for calculated torques that exceed a torque threshold stored in the nonvolatile, writable memory of the tool for the fastener;

(c10) verifying that motor current corresponds with the torque being generated;

(c11) stalling the motor upon achieving programmed torque until said trigger switches the tool to an idling state;

(c12) displaying on the alphanumeric display the programmed torque, a programmed speed, a maximum number of turns, and a number of output revolutions during the tool'"'"'s operation in the running state.

16. The method of claim 15 wherein the substeps of step (c) are repeated on a periodic basis.

17. The method claim 6 wherein step (b) comprises the following substeps:

(b1) copying performance records stored in one of at least two random access memory locations to a separate memory location contained within the housing of the tool and connected to the processor while continuing to save performance records to another random access memory location to prevent the loss of any data performance records;

(b2) upon the tool exiting a running state, selecting a number of performance records containing torque, turns count and time data for a finite set from all such records stored in the separate memory wherein for a previous running state of the tool, said finite set includes a record with the data for the first time the torque threshold was achieved, a record containing a peak torque achieved, and additional records containing predetermined turns count ratios based on the turns count between the time the torque threshold was achieved and the peak torque achieved; and

(b3) storing the finite set in the performance history in nonvolatile memory.

18. The method of claim 15 wherein the finite set contains five performance records having the record containing the data for the first time the torque threshold was achieved, the record containing the peak torque achieved, a record containing the data whose turns count value is one-quarter the turns count difference between the first and fifth data points, a record containing the data whose turns count value is one-half the turns count difference between the first and fifth data points, and a record containing the data whose turns count value is three-quarters the turns count difference between the first and fifth data points.

19. The method of claim 17 wherein the substeps (b1) and (b2) are performed on a periodic basis and the substep of (b3) is performed in part over several periods to prevent loss of data.

20. The method of claim 18 wherein the substeps (b1) and (b2) are performed on a periodic basis of five milliseconds period and the substep of (b3) is performed in part over several periods to prevent loss of data.