Expandable, mobile, modular microcomputer system for an off-road vehicle

• US 5,305,215 A
• Filed: 05/15/1991
• Issued: 04/19/1994
• Est. Priority Date: 05/15/1991
• Status: Expired due to Term

• Current Assignee: John Deere Electronic Solutions, Inc. (Deere & Company)
• Original Assignee: Phoenix International Corp (Deere & Company)
• Inventors: Batcheller, Barry D., Kallis, Adrian G., Brekkestran, Kevin L., Needham, Charles D.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US07/700,629
• Time in Patent Office: 1,070 Days
• Field of Search: 364/424.1, 364/424.03, 364/424.04, 74/866, 74/869, 74/335, 318/809, 395/275
• US Class Current: 701/51
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 2050/0045 using databus protocols
• CPC Class Codes: B60W 2050/021 Means for detecting failure or malfunction
• CPC Class Codes: B60W 30/18 Propelling the vehicle
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60Y 2200/14 Trucks; Load vehicles, Busses
• CPC Class Codes: F16H 2059/006 Overriding automatic control
• CPC Class Codes: F16H 2059/084 Economy mode
• CPC Class Codes: F16H 2059/085 Power mode
• CPC Class Codes: F16H 2059/743 using engine performance or power for control of gearing transmission input torque F16H2059/147
• CPC Class Codes: F16H 2061/0012 Transmission control for optimising power output of driveline
• CPC Class Codes: F16H 2061/0015 Transmission control for optimising fuel consumptions
• CPC Class Codes: F16H 2061/0255 Solenoid valve using PWM or duty-cycle control
• CPC Class Codes: F16H 2061/1208 with diagnostic check cycles; Monitoring of failures
• CPC Class Codes: F16H 2061/122 Avoiding failures by using redundant parts
• CPC Class Codes: F16H 2061/1228 Fixing failures by repairing failed parts, e.g. loosening a sticking valve
• CPC Class Codes: F16H 2061/1232 Bringing the control into a predefined state, e.g. giving priority to particular actuators or gear ratios
• CPC Class Codes: F16H 2061/1268 : Electric parts of the controller, e.g. a defect solenoid, wiring or microprocessor
• CPC Class Codes: F16H 2061/1292 : the failing part is the power supply, e.g. the electric power supply
• CPC Class Codes: F16H 59/40 : Output shaft speed
• CPC Class Codes: F16H 59/44 : dependent on machine speed of the machine, e.g. the vehicle
• CPC Class Codes: F16H 61/0213 : characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/08 : Timing control
• CPC Class Codes: F16H 61/12 : Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures
• CPC Class Codes: F16H 61/684 : without interruption of drive
• CPC Class Codes: F16H 61/70 : specially adapted for change-speed gearing in group arrangement, i.e. with separate change-speed gear trains arranged in series, e.g. range or overdrive-type gearing arrangements
• CPC Class Codes: F16H 63/36 : Interlocking devices

Abstract

An expandable, modular microcomputer system for an off-road vehicle having a controller which is operable to generate a plurality of independent pulse-width modulated control signals and a plurality of independent on/off control signals to a corresponding plurality of metal oxide silicone field effect transistors (MOSFETS). An RS-485 bi-directional serial communications interface enables the system to communicate with at least one other ingredient, external, controller. Thus, the control system can be modularly expanded to handle the needs of increasingly complex powershift transmissions. A watchdog circuit monitors operation of the controller and is supplied with a regulated voltage independent of the regulated voltage used to power the microcomputer. The watchdog can provide a reset signal to the microcomputer when spurious operation of the microcomputer is detected, as well as initiate operation of a back-up voltage supply circuit. The back-up voltage supply circuit is responsive to at least one analog input and operable to pulse-width modulate at least one of the MOSFETs to thereby control a clutch of a powershift transmission while operating in a "limp-home" mode. The system is particularly well-suited for controlling transmissions of heavy-duty off-road vehicles such as earth moving and other like vehicles, but can be readily adapted for use with transmissions of vehicles to be used to widely varying applications.

Claims

1. An expandable, mobile, field reprogrammable modular microcomputer system for controlling a powershift transmission of an off-road vehicle, said system comprising:

a microcomputer for receiving a plurality of analog input signals and a plurality of digital input signals and generating in response thereto a plurality of pulse-width modulated control signals and a plurality of on/off control signals;

a first voltage regulator for supplying a regulated supply voltage to said microcomputer to thereby power said microcomputer;

a second voltage regulator for supplying current to a controller coupled to at least one of said analog or digital inputs of said microcomputer;

means for providing communication between said microcomputer and said controller;

a first plurality of switching circuits responsive to said pulse-width modulated control signals of said microcomputer and operable to generate a plurality of independent, pulse-width modulated drive signals;

a watchdog circuit for monitoring said microcomputer and resetting said microcomputer when spurious operation of said microcomputer is detected;

an independent back-up voltage supply circuit for powering at least one of said first switching circuits in the event of spurious operation of said first voltage regulator;

a bi-directional serial communications interface in communication with said microcomputer for enabling serial communication between said microcomputer and a reprogramming device such that reprogramming device can reprogram said microprogram while said off-road vehicle is at a work site; and

display means responsive to said microcomputer for displaying information associated with the operation of said system.

2. The system of claim 1, wherein said bi-directional serial communications interface comprises an RS-485 bi-directional serial communications interface.

3. The apparatus of claim 1, further comprising a read-only memory associated with said microcomputer for storing program information for operating said microcomputer.

4. The system of claim 1, further comprising a low-voltage reset circuit responsive to said first voltage regulator for causing said watchdog circuit to reset said microcomputer when an output of said first voltage regulator drops below a predetermined voltage level.

5. The system of claim 1, wherein said back-up voltage supply circuit includes comparator means for comparing a fixed reference voltage with a varying control voltage from an external sensing device and generating an auxiliary pulse-width modulated control signal for pulse-width modulating at least one of said first switching circuits when said watchdog circuit has detected spurious operation of said microcomputer.

6. An expandable, mobile, field reprogrammable modular microcomputer system for controlling a powershift transmission of an off-road vehicle, said system comprising:

controller means for receiving at least one input from an external information generating device and for generating at least one pulse-width modulated output control signal and at least one on/off output control signal;

interface means coupled to said controller means for enabling bi-directional communication between said controller means and a reprogramming device such that said reprogramming device can be utilized to reprogram said controller means while said off-road vehicle is still at a work site and without removing said controller means from said off-road vehicle;

watchdog means for monitoring operation of said controller means and for generating a reset signal operable to reset said controller means when said watchdog means detects improper operation of said controller means;

means for independently powering said watchdog means;

means for monitoring said watchdog means and overriding operation of said watchdog means when said independent power means powering said watchdog means fails to supply a predetermined minimum power to said watchdog means;

at least one first switch means responsive to said pulse-width modulated control signal of said controller means for generating a pulse-width modulated drive signal; and

at least one second switch means responsive to said on/off control signal of said controller means for generating an on/off drive signal.

7. The system of claim 6, further comprising back-up power supply means for providing power to one of said first and second switch means.

8. The system of claim 6, further comprising memory means associated with said controller means for storing program information to control said controller means.

9. The system of claim 6, wherein said first and second switch means each comprise a metal oxide silicone field effect transistor.

10. An expandable, mobile, field reprogrammable modular microcomputer system for controlling a powershift transmission of a heavy-duty, off-road vehicle, said system comprising:

a plurality of current sourcing digital inputs;

a plurality of current sinking analog inputs;

a plurality of current sinking digital inputs;

a microcomputer responsive to said current sourcing digital inputs, said current sinking digital inputs, and said current sourcing analog inputs for generating a first plurality of independent, pulse-width modulated control signals and a second plurality of independent, on/off control signals;

circuit means for permitting and managing communication between said microcomputer and at least one additional controller system modularly and removably interfaced to said microcomputer;

a power supply;

a first voltage regulator responsive to said power supply for generating a first regulated voltage, said first regulated voltage being operable to power said microcomputer;

a second voltage regulator responsive to said power supply for generating a second regulated voltage, said second regulated voltage being operable to supply a current to said current sourcing digital inputs;

a watchdog circuit for monitoring operation of said microcomputer and generating a reset signal for resetting said microcomputer when said watchdog detects a condition of spurious operation of said microcomputer, and for generating a back-up voltage enabling signal when a malfunction of the microcomputer is detected;

a back-up voltage regulator circuit responsive to said back-up voltage enabling signal and at least one of said analog current sinking inputs for generating an auxiliary, pulse-width modulated control signal to control at least one of said first switching circuits;

a bi-directional serial communications interface circuit for enabling said microcomputer to communicate with a reprogramming device for reprogramming said microcomputer while said off-road vehicle is at a field work site; and

a multiplexer responsive to a plurality of said current sourcing analog inputs and said microcomputer for selectively coupling said plurality of current sourcing analog inputs with said microcomputer.