Distributed control system for forklift

1. A distributed control system comprising:

a plurality of controllers mounted on a forklift, said controllers for controlling corresponding functions of the forklift; and

a network for providing connections among said plurality of controllers, wherein:

a first controller of said plurality of controllers is configured to control a corresponding function of the forklift in response to an interface signal received from a second controller of said plurality of controllers; and

when the interface signal is not received from said second controller within a predetermined time period, said first controller controls the corresponding function of the forklift according to data stored thereon rather than controlling the corresponding function of the forklift in response to the interface signal.

2. The distributed control system according to claim 1 , further comprising a display unit connected to said network, wherein

the forklift includes internal combustion engine,

one of said first and second controllers is an engine controller, and another of said first and second controllers is a vehicle controller,

said vehicle controller generates a plurality of forklift component control signals for controlling forklift components in response to forklift component signals received from forklift components of the forklift,

said engine controller generates a plurality of engine control signals for controlling the internal combustion engine in response to a plurality of engine signals received from engine components of the internal combustion engine, and

said display unit displays at least one of the plurality of forklift component signals, the plurality of forklift component control signals, the plurality of engine signals, and the plurality of engine control signals.

3. The distributed control system according to claim 2 , wherein

said vehicle controller outputs at least one forklift component signal, selected from the plurality of forklift component signals, to said engine controller, and outputs the plurality of forklift component control signals, and

said engine controller is configured to receive the selected forklift component signal as the interface signal, and is configured to generate at least one of the plurality of engine control signals in response to the selected forklift component signal.

4. The distributed control system according to claim 3 , wherein

said engine controller uses data stored thereon rather than the selected forklift component signal to generate a first alarm signal, when the selected forklift component signal is not received within a predetermined time period, and

said display unit displays, in response to the first alarm signal, a first alarm notification that said engine controller did not receive the selected forklift component signal.

5. The distributed control system according to claim 3 , wherein

the at least one selected forklift component signal includes a vehicle speed signal indicating a speed of the forklift includes a vehicle speed limit signal indicating a speed limit of the forklift,

the plurality of engine signals includes an accelerator sensor signal indicating a state of an accelerator pedal of the forklift,

the plurality of engine control signals includes a fuel injection rate signal indicating an injection rate of the internal combustion engine, and

said engine controller generates the fuel injection rate signal in response to the vehicle speed signal, the vehicle speed limit signal, and the fuel injection rate signal.

6. The distributed control signal according to claim 2 , wherein

said engine controller outputs an engine signal, selected from the plurality of engine signals, to said vehicle controller, and outputs the plurality of engine control signals, and

said vehicle controller is configured to receive the selected engine signal as the interfacing signal, and is configured to generate at least one of the plurality of forklift component control signals in response to the selected engine signal.

7. The distributed control system according to claim 6 , wherein

said vehicle controller uses data stored thereon rather than the selected engine signal to generate a second alarm signal, when the selected engine signal is not received within a predetermined time period, and

said display unit displays, in response to the second alarm signal, a second alarm notification that said vehicle controller did not receive the selected engine signal.

8. The distributed control system according to claim 6 , wherein

the selected engine signal includes a rotation speed signal indicating a rotation speed of the internal combustion engine,

the plurality of forklift component signals includes a sitting detection signal indicating whether an operator is seated on a driver seat of the forklift,

the plurality of forklift component control signals includes a transmission control signal for controlling a transmission of the forklift, and

said vehicle controller generates the transmission control signal in response to the rotation speed signal and the sitting detection signal.

9. The distributed control system according to claim 2 , wherein

said plurality of controllers includes a finger chip controller for controlling a finger chip control module, and

said finger chip control module is disposed beside a driver seat of the forklift and is operable to control forks and a mast of the forklift in response to an actuation of a finger-operable lever of said finger chip control module.

10. The distributed control system according to claim 2 , wherein

said engine controller is disposed beside the internal combustion engine, and

said vehicle controller is positioned immediately inside a pivotable hatch of a body of the forklift.

11. A forklift comprising:

a forklift body; and

a distributed control system including:

a plurality of controllers mounted on said forklift body, said controllers for controlling corresponding functions of said forklift; and

a network for providing connections among said plurality of controllers, wherein:

a first controller of said plurality of controllers is configured to control a corresponding function of said forklift in response to an interface signal received from a second controller of said plurality of controllers; and

when the interface signal is not received from said second controller within a predetermined time period, said first controller controls the corresponding function of said forklift according to data stored thereon rather than controlling the corresponding function of said forklift in response to the interface signal.

12. A method of operating a distributed control system within a forklift, the method comprising:

transmitting an interface signal to a first controller of a plurality of controllers from a second controller of the plurality of controllers, the plurality of controllers being connected through a network and being configured to control corresponding functions of the forklift;

first controlling a first function of the forklift using the first controller in response to the interface signal; and

when the interface signal is not received from the second controller within a predetermined time period, second controlling the first function of the forklift using the first controller according to data stored thereon rather than controlling the corresponding function of the forklift in response to the interface signal.

13. The method according to claim 12 , further comprising:

displaying an alarm on a display screen of a display unit connected to the network when the first controller does not receive the interface signal within the predetermined time period, wherein

one of the first and second controllers is an engine controller, and another of the first and second controllers is a vehicle controller, and

the method further comprises:

using the vehicle controller to generate a plurality of forklift component control signals for controlling forklift components of the forklift; and

using the engine controller to generate a plurality of engine control signals for controlling an engine of the forklift in response to a plurality of engine signals received from engine components of the engine.

14. The method according to claim 13 , wherein

said transmitting of the interface signal includes

using the vehicle controller to output at least one forklift component signal, selected from the plurality of forklift component signals, to the engine controller, and to output the plurality of forklift component control signals, and

said first controlling of the first function includes

generating at least one of the engine control signals in response to the selected forklift component signal output from the engine controller.

15. The method according to claim 14 , wherein

said second controlling of the first function includes

using the data stored on the first controller rather than the selected forklift component signal when the selected forklift component signal is not received within the predetermined time period, and

said displaying of the alarm includes:

outputting a first alarm signal to the display unit from the vehicle controller; and

displaying a first alarm for providing notification that the engine controller did not receives the selected forklift component signal in response to the first alarm signal.

16. The method according to claim 14 , further comprising:

indicating a speed of the forklift according to a vehicle speed signal of the at least one selected forklift component signal;

indicating a speed limit of the forklift according to a vehicle speed limit signal of the at least one selected forklift component signal;

indicating a state of an accelerator pedal of the forklift according to an accelerator sensor signal of the plurality of engine signals;

indicating an injection rate of the engine according to a fuel injection rate signal of the plurality of engine control signals; and

generating the fuel injection rate signal using the engine controller and in response to the vehicle speed signal, the vehicle speed limit signal, and the fuel injection rate signal.

17. The method according to claim 13 , wherein

said transmitting of the interface signal includes

using the engine controller to output an engine signal, selected from the plurality of engine signals, to the vehicle controller, and to output the plurality of engine control signals, and

said first controlling of the first function includes

generating at least one of the plurality of forklift component control signals in response to the selected engine signal output from the vehicle controller.

18. The method according to claim 17 , wherein

said second controlling of the first function includes

using the data stored on the first controller rather than the selected engine signal when the selected engine signal is not received within the predetermined time period, and

said displaying of the alarm includes:

generating a second alarm signal when the vehicle controller does not receive the selected engine signal within the predetermined time period; and

displaying a second alarm for providing a notification that the vehicle controller did not received the selected engine signal in response to the second alarm signal.

19. The method according to claim 17 , further comprising:

indicating a rotation speed of the engine according to a rotation speed signal of the selected engine signal;

indicating whether an operator is seated on a driver seat of the forklift according to a sitting detection signal of the plurality of forklift component signals;

controlling a transmission of the forklift according to a transmission control signal of the plurality of forklift component control signals; and

using the vehicle controller to generate the transmission control signal in response to the rotation speed signal and the sitting detection signal.

20. A computer program stored on a computer-readable storage medium, the computer program for operating a distributed control system including a plurality of controllers connected through a network, the computer program causing a computer to execute a method comprising:

transmitting an interface signal to a first controller of the plurality of controllers from a second controller of the plurality of controllers;

first controlling a first function of the forklift using the first controller in response to the interface signal; and

when the interface signal is not received from the second controller within a predetermined time period, second controlling the first function of the forklift using the first controller according to data stored thereon rather than controlling the corresponding function of the forklift in response to the interface signal.

21. The computer program according to claim 20 , wherein the method further comprises:

displaying an alarm on a display screen of a display unit connected to the network when the first controller does not receive the interface signal within the predetermined time period.