GB2383310A

GB2383310A - Vehicle switching system control by external sensor

Info

Publication number: GB2383310A
Application number: GB0130340A
Authority: GB
Inventors: Murry Turner; Andy Cornwell
Original assignee: BOSS Manufacturing Ltd
Current assignee: BOSS Manufacturing Ltd
Priority date: 2001-12-19
Filing date: 2001-12-19
Publication date: 2003-06-25
Also published as: DE10260771A1; DE10260771B4; GB0130340D0

Abstract

An onboard system for switching a vehicle parameter to a pre-programmed value in response to a sensed external stimulus comprises a sensor 2 and a processor 32. The sensor 2 detects remote emitters of electromagnetic radiation such as infrared zone markers (40, see fig 5) in a warehouse, and may be mounted on top of the cab 9 of a forklift truck 6. Alternatively, the vehicle 6 may have a radiation source, emitting polarised light, for example, so that reflections from the environment or from bar codes may be received by the sensor 2. On receipt of a signal from the sensor 2, the processor 32 sets a parameter affecting engine speed, acceleration, deceleration, direction, tilt speed, lift speed, steering sensitivity or a combination of performance parameters. The system may also be configured to vary the gearing of a hydrostatic transmission by controlling the angle a of a swash plate 16.

Description

VEHICLE SWITCHING SYSTEM

The present invention relates to a vehicle switching system for automatically setting one or more performance parameters of a vehicle at pre-programmed values. The invention is particularly suitable for vehicles such as forklift trucks which are used to transport materials both inside and outside of buildings such as warehouses.

It is known for such vehicles to have various modes of operation which are defined by a set of pre-programmed performance parameters. The operational mode may be set manually by the operator of the vehicle depending on the location of the vehicle or the task being undertaken. This may be beneficial for making certain tasks easier to perform. The feature is also particularly useful as a safety device when operating in a congested environment where performance parameters such as a fast acceleration rate and high speeds may be a hazard both to the driver and to surrounding people and structures. However, such systems are open to abuse as it is up to the operator to manually set the operational parameters to suite the surrounding environment. In such a situation speed may be more of a priority to the operator than safety.

It would be useful to design a system which addresses the problems of the prior art arrangements described above.

According to a first aspect of the present invention there is provided a vehicle switching system for automatically setting at least one performance parameter of a vehicle at a pre-programmed value, the vehicle switching system comprising a sensor located on the vehicle for receiving an external stimulus and producing a signal, and processing means responsive to the signal from the sensor to set the performance parameter of the vehicle to the pre-

programmed value.

Preferably the external stimulus is an emitter of electromagnetic radiation.

Preferably the electromagnetic radiation is infrared radiation.

Preferably the emitter of electromagnetic radiation is remote of the vehicle.

Alternatively the emitter and receiver are located on the vehicle.

Advantageously the emitter emits a plurality of differently directed beams.

Preferably the emitter is arranged to emit polarized light and the receiver is arranged to receive polarized.

Advantageously the sensor is located on top of a cab of the vehicle.

Advantageously the sensor is sensitive to the frequency of the radiation received from the emitter such that the signal is different for different wavelengths of radiation received by the sensor.

Alternatively the sensor reads a bar code and the processing means is programmed to respond differently to different bar codes.

Preferably there is provided a holding circuit between the sensor and the processing means, the holding circuit arranged to hold the signal for a length of time during which the processing means can interpret the signal.

Advantageously there is provided a switching means, the switching means being arranged to switch the performance parameter of the vehicle to the pre-

programmed value.

Preferably the switching means is a mechanical relay.

Advantageously the mechanical relay is a latching relay.

Preferably the performance parameters affected by the vehicle switching system include one or more of the following: engine speed; acceleration forward; acceleration reverse; deceleration forward; deceleration reverse; direction changing response time; travel speed forward; travel speed reverse; tilt speed; auxiliary hydraulic speed; lift speed; steering sensitivity.

Advantageously two or more performance parameters are changed by the vehicle switching system.

Preferably the system is arranged to, after a failure or after vehicle power is lost, have the performance parameter set to the pre-programmed value.

Advantageously the vehicle has a hydrostatic transmission and the switching means varies the angle of the swash plate in order to vary the gearing between a power source of the vehicle and wheels of the vehicle.

Preferably the processing means is responsive to the signal to activate a warning means of the vehicle.

Advantageously there is provided 2 sensors, one located on either side of the vehicle. Preferably there is provided a direction switch, the direction switch being arranged to be in one state when the vehicle is forwardly engaged, and a different state when the vehicle is rearwardly engaged.

The invention is particularly suitable for the operation of forklift trucks which are used to transport materials both inside and outside of factories or warehouses. In such a situation it would be advantageous for the truck to be automatically switched into an indoor mode on entering the building and switched back into a normal mode of operation when leaving the building.

Problems encountered in implementing preferred embodiments of the invention may include: how to sense when entering a building without sensing while driving parallel to a door or past the end, if the door is near the corner of a building; how to detect vehicles approaching at an angle; and how to differentiate between entering and leaving the building. Further, the problem of two vehicles passing while entering or leaving the building should not prevent sensing.

One way to address these problems is to use a polarised infrared transmitter system to generate a narrow light curtain across the entrance projected down from the top right side. This allows the vehicle to approach at an angle and two vehicles to pass side by side. Any directional system could be used, for example, a bar code reader, a radio signal or a Doppler sensor. Using a receiver on each side of the vehicle solves the problem of detecting whether the vehicle is entering or leaving the building. By this method it is possible with the input from a direction switch, according to whether the truck is going forward or is in reverse, to easily determine if the vehicle should have inside or outside driving characteristics. For example, one particular set-up results in the following combinations: right sensor + forwardly engaged = entering the building; left sensor + reverse engaged = entering the building; left sensor + forward engaged = leaving the building; right sensor + reverse engaged = leaving the building.

Further problems may occur because of the narrow transmitter width resulting in the truck not being in the beam for a sufficient period for the computer clock to guarantee detection. This may be overcome by component selection of the sensors and by use of an electric latch to retain the signal until the opposite sensor resets it. In one embodiment of the invention this gave a latching time of approximately 50% of that of the computer and the latch holds indefinitely after power off to ensure the switch state remains even if the truck is moved.

Being electrical as opposed to electronic it should have greater immunity to electrical signal spikes.

One example of the present invention as described above, is a vehicle switching system which can be switched between different modes of operation by an operator, but which may automatically be switched into a particular mode by some external stimulus, over-riding the manual control.

Such a system is designed to increase safety in the work place by removing the onus on the operator of the vehicle to select a mode of operation which is suitable for the surroundings. Further, the requirement of the driver to operate a switching device on entering a particularly hazardous environment, which may actually increase the safety risk for a brief period, is removed.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a side view of an embodiment of the present invention in which a forklift truck is fitted with a vehicle switching system.

Figure 2 is a photograph of an embodiment of the present invention showing a sensor mounted on the load guard of a forklift truck.

Figure 3 is a photograph of an embodiment of the present invention showing a switch for manually switching between different modes of operation.

Figure 4 shows a schematic diagram of an embodiment of the present invention in which a vehicle switching system is coupled to an engine and a hydrostatic transmission.

Figure 5 shows a front view of an embodiment of the present invention in which a vehicle switching system is operating in the doorway of a warehouse.

Figures 1-5 show an embodiment of a vehicle switching system in accordance with the present invention. Referring firstly to Figure 1, two infrared sensors (2) are mounted on either side of an upper portion of the load guard (4) of a forklift truck (6). A manual switch (8) for switching between operating modes

is provided within the cab (9). The operator of the forklift truck (6) may thus select a particular set of performance parameters which are preprogrammed as the 5 operating modes shown in Table 1. However, activation of the infrared sensor (2) can over-ride the manual controls (8) and automatically switch the truck (6) into one of the modes to suit a designated area. For example, in one embodiment activation of the infrared sensor (2) can over-

ride the manual controls (8) and automatically switch the truck (6) into warehouse mode. Sensors (2) can be mounted to either side of a forklift truck (6). Figures 2 and 3 show photographs of a sensor (2) mounted on an upper portion of the load guard (4) of a forklift truck (6) and a manual switch (8) located within the cab (9) of the vehicle respectively.

o 2 G =, e an Is c À= (D Q) al Q) g (D CUSS.m Mode Description In <: n cat cat a:

1 Safety / Economy 75 1 1 3 3 3 65 65 3 3 1 2 Warehouse 85 3 3 3 3 3 80 80 5 1 3 3 General Purpose 100 3 3 3 3 4 100 100 5 3 3 4 Outside Operation 100 1 3 3 3 3 100 80 5 3 5 5 Shuttle 100 5 5 5 5 5 75 75 5 5 3 Rapid / Aggressive 5 À 4 Moderate 3 Gradual / Smooth 1 Table l: Example of parameters for 5-mode switch settings.

Figure 4 shows an engine (10) connected via a drive coupling to a piston group (18) internal to the hydrostatic pump (20). The engine (10) provides the rotational power to the piston group (18) causing the pistons to reciprocate providing output from the hydrostatic pump (20). The angle +/- a of the swash plate (16) determines the direction and volume of the output. The larger the angle (a) of the swash plate the greater the distance the pistons (18) are driven in and out by rotation of the piston group against the swash plate. The hydrostatic pump (20) is connected to the hydrostatic motor(s) via hydraulic connections and transfers power directly or indirectly to the wheels. A processing means (32) is connected to the engine, the hydrostatic pump and the operator's driving controls. The processing means (32) is further connected to a manually operated switch (8) which is located in the loadguard/cab (9) of the forklift truck (6) and two sensors (2) located on both sides of an upper portion of the loadguard/cab.

In the normal mode of operation the processing means (32) receives input from the manually operated switch (8) to determine which of the five modes of operation the operator has manually selected. The processing means (32) monitors and controls the engine and hydrostatic pump of the forklift truck (6) within the pre-programmed values of the particular operating mode selected by the operator of the forklift truck. The driving characteristics are derived from the engine performance and angle (a) of the swash plate. For example, the travel speed is proportional to the angle (a) of the swash plate multiplied by the engine speed, where maximum engine speed with maximum swash plate angle gives maximum travel speed. The rate of acceleration or deceleration is dependent upon the reaction times of the engine and the swash plate to obtain the maximum or minimum setting.

For normal operation outside a designated area, the operator of the forklift truck may select between the five operating modes shown in table 1.

However, on entering the designated area one of the sensors (2) receives an infrared beam (38) from the infrared emitter (40) situated in the top corner of the doorway (42) as shown in Figure 5. On receiving the infrared beam (38), the sensor (2) sends a signal to the processing means (32). The processing means (32) also receives information from the direction switch (36), which is set according to whether the truck (6) is forwardly engaged or rearwardly engaged. Having received input from one of the infrared sensors (2) and the direction switch (36), the processing means (32) is programmed to determine that the truck (6) is entering the warehouse and over-rides the manual switching controls (8), automatically setting the driving characteristics to the pre-programmed values corresponding to the desired mode. When the truck (6) leaves the designated area one of the sensors (2) again receives an infrared beam (38) and sends another signal to the processing means (32).

Using the input from the direction switch (36) and the infrared sensor (2) the processing means (32) is programmed to determine that the truck (6) is leaving the designated area and switches back into the normal mode of operation in which the operator may select any of the five operating modes.

Figure 5 shows two such trucks (6) in the entrance (42) of a warehouse for example. The infrared emitter (40) is situated in the top right hand corner of the doorway (42) and emits an array of polarised infrared beams (38) to generate a narrow light curtain across the entrance projected down from the top right side. This allows a vehicle to approach at an angle and two vehicles to pass side by side while still triggering the infrared sensors (2). if the truck (6a) is forwardly engaged and receives a signal from the right hand sensor (2) then the processing means (32) is programmed to switch into the desired mode. However, if the truck (6a) is rearwardly engaged and receives a signal from the right hand sensor then the processing means is programmed to switch into the normal mode. Similarly, if the truck (fib) is forwardly engaged and receives a signal from the left hand sensor then the processing means is programmed to switch into normal mode. However, if the truck (6b) is rearwardly engaged and receives a signal from the left hand sensor then the processing means is programmed to switch into the desired mode.

If the truck approaches the light beam quickly then the period during which the sensor (2) senses the light beam will be short. To ensure that the processor (32) receives a signal as the light beam is sensed there is preferably a hold circuit between each sensor and the processor (32) which holds the received signal for a period. The period may suitably be around 4 clock cycles of the processor. If there is more than one entrance to the warehouse then the emitters (40) should be set at the same side of each entrance with respect to inward/outward movement of trucks.

It is advantageous for the emitter to be positioned in an upper corner of the entrance and to emit a curtain of radiation projected down and across the entrance. Such an arrangement can allow two trucks to pass in the throughway and both receive a signal from the emitter.

It is advantageous for the sensors to be positioned on the truck so that an operator, positioned in a normal operating position, cannot reach the sensors.

Such an arrangement inhibits the operator of the truck from covering the sensors when entering the warehouse. For this purpose the sensors could be located on the lifting mechanism of the truck, preferably at the top of it.

Other systems to detect zones of operation could be used. For example, the truck could carry light emitters and the sensors (2) could then sense light reflected back to the truck off characteristic signs set at the entrances to the warehouse. The signs could, for example, carry bar codes and a bar code reader on the truck could read the code and determine the location of the truck. Another system would be to replace light emitters (40) with ultrasound emitters and to replace the sensors (2) with ultrasound sensors.

Different frequencies of radiation could be used to detect different zones of operation. For example, the truck could carry infrared sensors that are sensitive to different frequencies, and emitters of infrared radiation of different

frequencies could be set at the entrances to the warehouse. In one arrangement a first emitter, with a first frequency, is positioned on one side of the entrance, and a second emitter, with a second frequency, is positioned on the other side of the entrance. One particular set-up according to this arrangement results in the following combinations: [right sensor (first frequency) and/or left sensor (second frequency)] + forwardly engaged = entering the building; [right sensor (first frequency) and/or left sensor (second frequency)] + reverse engaged = leaving the building; [right sensor (second frequency) anchor left sensor (first frequency)] + forwardly engaged = leaving the building; [right sensor (second frequency) and/or left sensor First frequency)] + reverse engaged = entering the building. Such an arrangement has the advantage that even if one of the signals is blocked the switching system still functions.

A pole could be positioned in the middle of the entrance to provide two lanes for entering and leaving the warehouse. Such an arrangement prevents vehicles passing the throughway at a steep angle, which may result in the sensors not receiving the emissions from the emitter in particular arrangements. Other embodiments of the present invention are also envisaged. For example, within the warehouse there may be provided various zones of operation and different operating modes may be automatically selected on entering the different zones. There may be three or more such zones. Such zones may be signalled by different emitter frequencies for emitters (40) or by different bar codes, which could be detected on the truck.

Although the detailed description above relates to the selection of

performance parameters by altering the engine speed and the swash plate angle in a hydraulic transmission, the invention is suitable for selecting performance parameters by other switching means. For example, in the present embodiment, a switching means is provided to vary the tilt speed of the forks of the truck according to the mode of operation. In the present

embodiment values of 11 performance parameters are grouped into 5 operating modes as shown in Table 1. However, further performance parameters may also be envisaged with suitable switching means for varying said parameters. Embodiments with more or fewer than five pre- programmed operating modes are also envisaged.

The arrangement of the vehicle switching system with a hydraulic transmission is advantageous as there is a certain amount of free-play between the switching means and the performance parameter thus resulting in a smooth transition on switching from one mode to another. For example, if the engine speed and angle of the swash plate are suddenly altered from the settings in mode 5, to those in mode 1, then the motion of the fluid in the hydraulic pumps will slow and transmit the change in speed of flow to the wheels more smoothly than a transmission system which does not have such a hydraulic buffering effect. However, it is noted that this is one preferred embodiment, and other embodiments using different transmission systems are also envisaged.

Although the embodiment of the vehicle switching system described in detail above is fitted to a forklift truck, the invention is suitable for fitting to any type of vehicle. For example, another embodiment would provide emitters on the side of the road at the entrance to reduced speed zones such that any vehicle fitted with an embodiment of the invention would automatically slow to the required speed. Different vehicles may have different performance parameters with correspondingly different switching means.

While this invention has been particularly shown and described with reference to preferred embodiments and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims

Claims:

1. A vehicle switching system for automatically setting at least one performance parameter of a vehicle at a pre-programmed value, the vehicle switching system comprising a sensor located on the vehicle for receiving an external stimulus and producing a signal, processing means responsive to the signal from the sensor to set the performance parameter of the vehicle to the pre-programmed value.

2. A vehicle switching system as claimed in claim 1, wherein the external stimulus is an emitter of electromagnetic radiation.

3. A vehicle switching system as claimed in claim 2, wherein the electromagnetic radiation is infrared radiation.

4. A vehicle switching system as claimed in any previous claim, wherein the emitter of electromagnetic radiation is remote of the vehicle.

5. A vehicle switching system as claimed in any of claims 1 to 3, wherein the emitter and receiver are located on the vehicle.

6. A vehicle switching Stem as claimed in any previous claim, wherein the emitter emits a plurality of differently directed beams.

7. A vehicle switching system as claimed in any previous claim, wherein the emitter is arranged to emit polarized light and the receiver is arranged to receive polarized.

8. A vehicle switching system as claimed in any previous claim, wherein the sensor is located on top of a cab of the vehicle.

9. A vehicle switching system as claimed in any previous claim, wherein the sensor is sensitive to the frequency of the radiation received from the emitter such that the signal is different for different wavelengths of radiation received by the sensor.

10. A vehicle switching system as claimed in any previous claim, wherein the sensor reads a bar code and the processing means is programmed to respond differently to different bar codes.

11. A vehicle switching system as claimed in any previous claim, wherein there is provided a holding circuit between the sensor and the processing means, the holding circuit arranged to hold the signal for a length of time during which the processing means can interpret the signal.

12. A vehicle switching system as claimed in any previous claim, wherein there is provided a switching means, the switching means being arranged to switch the performance parameter of the vehicle to the pre-programmed value.

13. A vehicle switching system as claimed in claim 12, wherein the switching means is a mechanical relay.

14. A vehicle switching system as claimed in claim 13, wherein the mechanical relay is a latching relay.

15. A vehicle switching system as claimed in any previous claim, wherein the performance parameters affected by the vehicle switching system include one or more of the following: engine speed; acceleration forward; acceleration reverse; deceleration forward; deceleration reverse; direction changing response time; travel speed forward; travel speed reverse; tilt speed; auxiliary hydraulic speed; lift speed; steering sensitivity.

16. A vehicle switching system as claimed in any previous claim, wherein 2 or more performance parameters are changed.

17. A vehicle switching system as claimed in any previous claim, wherein the system is arranged to, after a failure or after vehicle power is lost, have the performance parameter set to the pre-programmed value.

18. A vehicle switching system as claimed in any previous claim, wherein the vehicle has a hydrostatic transmission and the switching means varies the angle of the swash plate in order to vary the gearing between a power source of the vehicle and wheels of the vehicle.

19. A vehicle switching system as claimed in any previous claim, wherein the processing means is responsive to the signal to activate a warning means of the vehicle.

20. A vehicle switching system as claimed in any previous claim, wherein there is provided 2 sensors, one located on either side of the vehicle.

21. A vehicle switching system as claimed in any previous claim, wherein there is provided a direction switch, the direction switch being arranged to be in one state when the vehicle is forwardly engaged, and a different state when the vehicle is rearwardly engaged.

22. A vehicle switching system substantially as described herein with reference to Figures 1-5 of the accompanying drawings.