Wireless foot control system with optical transmitter and transceiver

• US 7,428,439 B1
• Filed: 01/13/2005
• Issued: 09/23/2008
• Est. Priority Date: 01/13/2005
• Status: Expired due to Fees

• Current Assignee: Linemaster Switch Corporation
• Original Assignee: Linemaster Switch Corporation
• Inventors: Reynolds, Charles A., Argraves, Gary L.
• Primary Examiner(s): HARTMAN JR, RONALD D
• Application Number:
  US11/035,203
• Time in Patent Office: 1,349 Days
• Field of Search: 700/17, 700/83, 318/400.18, 318/551
• US Class Current: 700/17
• CPC Class Codes: G06F 3/0334 Foot operated pointing devices
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device

Abstract

A wireless foot control system includes a receiver and at least one transmitter. The transmitter includes a medium generator for emitting a communication medium, a power supply and at least one foot pedal. The power supply includes a power source, a capacitor bank having a discharge current capacity sufficient to power the medium generator, and a current limiter. The current limiter connects the power source to the capacitor bank, charging the capacitor bank from the power source over a period of time. The foot pedal selectively energizes the medium generator from the capacitor bank. The receiver includes a medium collector for collecting the emitted medium and an electronic circuit. The electronic circuit includes a converter for converting the collected medium to an input control signal and a microprocessor in communication with the converter, the microprocessor having an operating system for generating an output control signal commensurate with the input control signal.

Claims

1. A wireless foot control system comprising:

at least one transmitter including

a medium generator for emitting a communication medium;

a power supply having

a power source,

a capacitor bank having a discharge current capacity sufficient to power the medium generator, and

a current limiter, connecting the power source to the capacitor bank, the current limiter charging the capacitor bank from the power source over a period of time; and

at least one foot pedal for selectively energizing the medium generator from the capacitor bank and

a receiver including

a medium collector for collecting the emitted medium; and

an electronic circuit including

a converter for converting the collected medium to an input control signal and

a microprocessor in communication with the converter, the microprocessor having an operating system for generating an output control signal commensurate with the input control signal.

2. The wireless foot control system of claim 1 wherein the medium generator is a plurality of infrared light-emitting diodes arranged to emit an evenly distributed infrared light wave pattern and the medium collector is a plurality photodiodes that are active in the infrared wavelength.

3. The wireless foot control system of claim 2 wherein the medium generator is composed of ten infrared light-emitting diodes arranged in a circular pattern and the medium collector is composed of six photodiodes arranged in a circular pattern.

4. The wireless foot control system of claim 1 wherein the system includes four or less transmitters.

5. A method for controlling a piece of equipment with a wireless foot control system, the foot control system comprising a receiver and at least one transmitter;

the transmitter including a medium generator, a microprocessor having an operating system, and at least one foot pedal;

the receiver including a medium collector and a microprocessor having an operating system, the method comprising the steps of;

transmitting bounded randomized data packets indicative of actuation of the transmitter by

depressing the at least one foot pedal to actuate the transmitter microprocessor,

the transmitter operating system generating a control signal for the medium generator,

the control signal energizing the medium generator to emit a communication medium defining the data packets;

generating an output control signal for controlling the piece of equipment by

collecting the emitted communication medium with the medium collector,

examining the data packets for errors and

generating an output control signal for valid data packets.

6. The method of claim 5 wherein the step of generating a control signal for the medium generator comprises dividing a 2000 ms cycle time into 32 hop slots by

assigning a period base to each hop slot based on a setting of a microprocessor dip switch;

generating a random delay for each hop slot, the delay being bounded in a range of the assigned period base; and

normalizing the delay.

7. The method of claim 6 wherein the step of generating a random delay includes seeding the random generator with a customer code and the assigned station number.

8. The method of claim 6 wherein the normalized delay is equal to period base of the previous hop slot minus the selected delay period of the previous hop slot plus the selected delay period of the current hop slot.

9. The method of claim 5 wherein the step of examining the data packets for errors comprises:

examining each data packet for collisions and

examining each data packet for validity.

10. The method of claim 9 wherein each data packet has a bit period including an active high state followed by a low state gap, the high state and the low state each having a length, and the step of examining a data packet for collisions comprises comparing the high state length to a predetermined length.

11. The method of claim 10 wherein the transmitter operating system separates each prior data packet from each subsequent data packet with a trailing guard period having a predetermined length, and the step of examining a data packet for collisions also comprises comparing the trailing guard period between each prior data packet and each subsequent data packet with the predetermined trailing guard period length.

12. The method of claim 5 wherein the transmitter operating system includes:

an initialization routine for resetting the transmitter on initial energization;

a transmit wait routine for maintaining the transmitter in a wait state until a change in the pedal state is detected;

a transmit bit frame routine for transmitting the control signal when the transmit wait routine detects a change in the pedal state;

a test for off routine and a first packet test routine for returning the transmitter to the wait state on completion of transmission of the control signal.

13. The method of claim 12 wherein the transmit bit frame routine:

initially obtains a bit value

then queries whether the bit value is high;

if the bit value is high, the microprocessor transmits a HIGH bit to the medium generator;

if the bit value is not high, the microprocessor sends a LOW bit to the medium generator;

delays the gap period;

decrements bitCount;

queries whether all bits have been sent

if all of the bits have not been sent, the microprocessor loops back to obtains the bit value,

if all of the bits have been sent, the microprocessor exits the transmit 32 bit frame routine and initiates the test for off routine.

14. The method of claim 5 wherein the receiver operating system includes:

an initialization routine for resetting the transmitter on initial energization;

a receiver idle routine for maintaining the receiver in a wait state until a “

start bit”

(low to high transition) is received;

a start bit receipt routine;

a verification routine;

a main receiver routine;

an error check routine; and

a return to receiver idle routine.

15. The method of claim 14 wherein the start bit receipt routine:

determines whether the a failsafe timer has timed-out;

if the failsafe timer has timed-out, the micro-controller queries whether the idle period has been met;

if the idle period has not been met, the micro-controller exits the start bit receipt routine and restarts the receiver idle routine,

if the idle period has been met, the micro-controller queries whether a high state has been encountered,

if the failsafe timer has not timed-out, the micro-controller queries whether a high state has been encountered;

if a high state has not been encountered, the micro-controller loops back to the beginning of the start bit receipt routine;

if a high state has been encountered

the micro-controller initializes the timer count at the “

start bit”

leading edge, and

seeks the end of the start bit;

if the end of the start bit has been encountered

the micro-controller saves the timer tick count when the low state was detected,

exits the start bit receipt routine, and

initializes the start bit verification routine;

if the end of the start bit has not been encountered the micro-controller saves “

0”

to Frame error, exits the start bit receipt routine, and returns to the receiver idle routine.

16. The method of claim 14 wherein the start bit verification routine:

tests the start bit width;

if the start bit width is too short

the micro-controller saves “

1”

to IR Glitch Error,

exits the start bit verification routine, and

returns to the receiver idle routine;

if the start bit width is not too short

the micro-controller sets the received bit count to 1,

counts the start bit in the frame bit counter,

exits the start bit verification routine, and

initiates the main receiver routine.

17. The method of claim 14 wherein the main receiver routine samples the control signal received by the receiver and

queries whether the bit state is high;

if the bit state is not high, the micro-controller queries whether the timeout period has been reached,

if the timeout period has been reached, the micro-controller exits to the receiver idle routine,

if the timeout period has not been reached the micro-controller resamples the signal;

if the bit state is high, the micro-controller tests the tick count;

if the tick count is less than a predetermined value, the micro-controller exits to the receiver idle routine;

if the tick count is not less than the predetermined value, the micro-controller tests the ticks zero span;

if the ticks zero span is greater than a predetermined value, the micro-controller exits to the receiver idle routine;

if the ticks zero span is not greater than the predetermined value, the micro-controller tests the bit count;

if the bit count is greater than a predetermined value, the micro-controller exits to the receiver idle routine;

if the bit count is not greater than the predetermined value, the micro-controller

rolls the received bits,

saves the bit values,

saves the high bit value and the stop bit,

slides the last timer value, and

tests for Low bit state;

if a Low state is not detected, the micro-controller tests whether it has timed out while seeking the Low state,

if the timeout period has been reached, the micro-controller exits to the receiver idle routine,

if the timeout period has not been reached the micro-controller resamples the signal;

if a Low state is detected, the micro-controller queries whether all bits have been received;

if all bits have not been received, the micro-controller resamples the signal; and

if all bits have been received, the micro-controller exits the main receiver routine and initiates the error check routine.

18. The method of claim 14 wherein the error check routine queries whether the last bit was the high “

stop bit”

;

if the last bit was the high stop bit, the micro-controller exits the error check routine and returns to the receiver idle routine

if the last bit was not the high stop bit, the micro-controller queries whether the data is collision data;

if the data is collision data, the micro-controller exits the error check routine and returns to the receiver idle routine;

if the data is not collision data, the micro-controller

records all of the bits in the frame and

conducts internal collision bit checking

if an internal collision bit is detected, the micro-controller exits the error check routine and returns to the receiver idle routine;

if an internal collision bit is not detected, the micro-controller checks other internal collision test bit couplets;

if both “

High-Low” and

“

Low-High”

couplets are not detected, the micro-controller exits the error check routine and returns to the receiver idle routine;

if both “

High-Low” and

“

Low-High”

couplets are detected, the micro-controller checks the processed serial data that has been received

if the values do not match, the micro-controller exits the error check routine and returns to the receiver idle routine

if the values match, the micro-controller tests that the transmitter station ID matches the receiver station ID set in the receiver dipswitches

if the station IDs do not match, the micro-controller exits the error check routine and returns to the receiver idle routine

if the station IDs match, the micro-controller tests whether the pedal combinations are valid

if the pedal combinations are not valid, then the micro-controller exits the error check routine and returns to the receiver idle routine

if the pedal combinations are valid, the micro-controller exits the error check routine and initiates the return to receiver idle routine.