Safety System for a Baggage Tractor

Abstract

A safety system for a baggage tractor is provided that addresses the problems associated with tipping over or flipping of vehicles due to excessive speed around turns. Additionally, the safety system for a baggage tractor is provided that is fully integrated to ease replacement of a combustion engine in a baggage tractors with an electric motor and automated safety control system.

Claims

1. A safety system for a baggage tractor having an electric motor connected to a battery for propelling the baggage tractor, the safety system comprising: a motor controller connected to the electric motor via a wiring harness; at least one sensor generating data relating to a magnitude of a g-force generated by the movement of the baggage tractor, the data transmitted from said at least one sensor to said motor controller; a processor in said motor controller; a storage accessible by said processor, said storage having at least one threshold value saved thereon; said processor receiving the data generated by the at least one sensor and comparing the data to the at least one threshold value, wherein when the data equals or exceeds the threshold value, said processor causes said motor controller to automatically reduce power transmitted from the battery to the electric motor to thereby cause a reduction in the speed of the baggage tractor.

2. The safety system according to claim 1, wherein said motor controller and said at least one sensor are provided as a retrofit assembly integrated with a wiring harness and adapted to be retrofit into an existing baggage tractor.

3. The safety system according to claim 2, wherein said wiring harness further comprises: a throttle pedal connected to said motor controller via the wiring harness; and a brake pedal connected to said motor controller via the wiring harness.

4. The safety system according to claim 1, wherein said at least one sensor comprises an accelerometer.

5. The safety system according to claim 4, wherein the accelerometer is provided integral with the motor controller.

6. The safety system according to claim 1, wherein the threshold value is selectable or programmable.

7. The safety system according to claim 6, wherein the threshold value comprises a first threshold value and a second threshold value, and wherein both the first and second threshold values are selectable or programmable.

8. The safety system according to claim 7, wherein if the data received does not exceed the first or second threshold values, the motor controller does not reduce the power transmitted to the electric motor based on the received data; wherein if the data received exceeds the first threshold value but does not exceed the second threshold value, the motor controller will reduce the power transmitted to the electric motor proportional to the value of the data between the first and second threshold, and wherein if the data received exceeds the second threshold value, the motor controller will reduce the power transmitted to the electric motor by a maximum selected or programmed amount.

9. The safety system according to claim 1, further comprising a second sensor selected from the group consisting of: a steering angle sensor, a speed sensor, and a tilt sensor.

10. The safety system according to claim 9, wherein when the second sensor is selected as a steering angle sensor that generates steering angle data, a second threshold value is saved in said storage and when a magnitude of the steering angle data reaches said second threshold value, said motor controller automatically reduces power transmitted from the battery to the electric motor.

11. The safety system according to claim 9, wherein when the second sensor is selected as a speed sensor that generates speed data, a second threshold value is saved in said storage and when a magnitude of the speed data reaches said second threshold value, said motor controller automatically reduces power transmitted from the battery to the electric motor.

12. The safety system according to claim 11, wherein the second threshold value comprises a range of values and the motor controller will reduce the power transmitted to the electric motor proportional to the value of the signal within the range.

13. The safety system according to claim 9, wherein when the second sensor is selected as a tilt sensor that generates inclination data, a second threshold value is saved in said storage and when a magnitude of the inclination data reaches said second threshold value, said motor controller automatically reduces power transmitted from the battery to the electric motor.

14. The safety system according to claim 13, wherein the second threshold value comprises a range of values and the motor controller will reduce the power transmitted to the electric motor proportional to the value of the signal within the range.

15. The safety system according to claim 1, further comprising a transceiver connected to said processor, said transceiver receiving wireless signals from a remote computer to remotely adjust the threshold value saved on said storage.

16. The safety system according to claim 15, wherein the threshold value is automatically adjusted based on programmed criteria selected from the group consisting of: a date, current local weather conditions, human resources information and combinations thereof.

17. A method of safety operating a baggage tractor having an electric motor connected to a battery for propelling the baggage tractor, the method comprising the steps of: connecting a motor controller to the electric motor via a wiring harness; connecting at least one sensor to a processor; generating g-force data with the at least one sensor, the magnitude of the g-force data being related to a g-force acting on the at least one sensor due to the baggage tractor turning; transmitting the g-force data from the at least one sensor to the processor; comparing the g-force data to a threshold value saved on a storage and accessible by the processor; wherein when the data equals or exceeds the threshold value, the motor controller automatically reduces power transmitted from the battery to the electric motor to thereby cause a reduction in the speed of the baggage tractor.

18. The method according to claim 17, further comprising the steps of: selecting or programming the threshold value; and saving the selected or programmed threshold value on the storage.

19. The method according to claim 18, wherein the threshold value comprises a first threshold value and a second threshold value, and wherein both the first and second threshold values are selectable or programmable.

20. The method according to claim 18, wherein if the data received does not exceed the first or second threshold values, the motor controller does not reduce the power transmitted to the electric motor based on the received data; wherein if the data received exceeds the first threshold value but does not exceed the second threshold value, the motor controller reduces the power transmitted to the electric motor proportional to the value of the data between the first and second threshold, and wherein if the data received exceeds the second threshold value, the motor controller will reduce the power transmitted to the electric motor by a maximum selected or programmed amount.

21. The method according to claim 17, further comprising the steps of: connecting a speed sensor to the processor; generating speed data with the speed sensor; transmitting the speed data to the processor; saving a second threshold value on the storage; comparing the speed data to the second threshold value; automatically reducing power transmitted from the battery to the electric motor when the speed data reaches or exceeds the second threshold value.

22. The method according to claim 21, wherein the second threshold value comprises a range of values and the motor controller reduces the power transmitted to the electric motor based on the value of the speed data within the range.

23. The method according to claim 17, further comprising the steps of: connecting a tilt sensor to the processor; generating inclination data with the tilt sensor; transmitting the inclination data to the processor; saving a second threshold value on the storage; comparing the inclination data to the second threshold value; automatically reducing power transmitted from the battery to the electric motor when the inclination data reaches or exceeds the second threshold value.

24. The method according to claim 23, wherein the second threshold value comprises a range of values and the motor controller reduces the power transmitted to the electric motor based on the value of the inclination data within the range.

25. The method according to claim 17, further comprising the steps of: connecting the processor to a transceiver; receiving wireless signals with the transceiver from a remote computer; and adjusting the threshold value saved on said storage.

26. The method according to claim 17, wherein the threshold value is automatically adjusted based on programmed criteria selected from the group consisting of: a date, current local weather conditions, human resources information and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a diagram of the safety system for a baggage tractor system integrated into a vehicle.

[0026] FIG. 2 is a diagram of the safety system for a baggage tractor according to FIG. 1.

[0027] FIG. 3 is a diagram of the motor controller according to FIG. 1.

[0028] FIG. 4 is an illustration of a baggage tractor and baggage cart train going into a turn.

[0029] FIG. 5 is a diagram of a decision tree depicting the different decisions made by the motor controller of FIG. 3 based on input information.

[0030] FIG. 6 is a schematic diagram for the g-force sensor, the motor controller, and the battery.

DETAILED DESCRIPTION OF THE INVENTION

[0031] Referring now to the drawings, wherein like reference numbers designate corresponding structure throughout the views. The following examples are presented to further illustrate and explain the present invention and should not be taken as limiting in any regard. Likewise, the illustrations and drawings are not provided to scale and are provided to further explain and illustrate the novel features of the invention.

[0032] FIG. 1. is a diagram of the safety system for a baggage tractor integrated into a vehicle safety system such as, a baggage tractor. The integrated vehicle system 100 includes a power source 102 that could comprise a lithium-ion battery, and a battery management system 104 that could also include a DC to AC power inverter. Power is transmitted from battery management system 104 to the motor 106. The motor 106 drives a load 108, in this instance, the wheels of a baggage tractor. Feedback information is read by a motor encoder feedback 110, which may comprise an encoder with a variable voltage output. Signals from the motor encoder feedback 110 are then transmitted to a motor controller 112. The motor controller 112 also accepts input signals 114 from other sources, which provide additional information for adjustment of the power transmitted from the battery management system 104 to the motor 106. The input signals 114 may include a voltage output from a sensor, such as an accelerometer (e.g., a 0-5V analog signal), but could also include an array of other types of signals from various sensors.

[0033] In one embodiment, the motor controller 112 comprises a Programmable Logic Circuit (PLC) where software is added to achieve the functionality described herein. In another configuration, it is contemplated that an accelerometer and/or an inclinometer may be provided integral with the motor controller 112.

[0034] Referring to FIG. 2, the safety system for a baggage tractor is shown in greater detail. The motor controller 112 is provided with input signals from an accelerometer 202, measuring g-forces acting upon the baggage tractor when the vehicle turns while being propelled. The motor controller 112 is also adapted to receive additional sensor signals, such as a steering radius measurement 204 or other sensor readings 206. The other sensor readings 206 may include, for example, a tilt sensor providing information on the inclination of the baggage tractor, or a speed sensor that could measure the rotational speed of the wheels, and the like.

[0035] The motor controller is powered by a power source 208, which could comprise a DC power source such as a dedicated power supply. The motor controller 112 when comparing the various measured values (e.g., g-force, tilt, speed, etc.) may provide an altered throttle signal 210 to affect a change in speed of the vehicle. Other signals may include a braking system signal 212 that could automatically apply the brakes if the sensor inputs exceed a threshold. Additionally, the motor controller 112 may send out additional signals for interaction with other various control mechanisms 214.

[0036] Now referring to FIG. 3, the motor controller 112 is shown in greater detail. The program memory 302 contains a looping program that, in one configuration, may only be changed through an external update. The clock 304 controls the speed at which the CPU 308 (e.g., processor) executes instructions and performs certain operations. The input signals 306 may include any or all signals coming from peripheral devices. The data memory 310 allows for temporary variables from which the CPU can read or write. The data memory may further include an array of threshold values related to various measured signals including, for example, a threshold g-force, a threshold inclination, a threshold speed and the like. It is understood that the CPU 308 may compare any of the input data from such sensors to the corresponding threshold values to alter the power being transmitted to the motor. It is further understood that the combination of measured values may impact how the motor controller 112 alters the power. For example, if the inclination of the baggage tractor is read as 6 degrees to the right had side of the baggage tractor, this may function to the lower the g-force threshold when the baggage tractor is turning to the left, but increase the threshold when the baggage tractor is turning to the right according to the programming. The same may be true of the speed sensor and any additional sensors that may be used. The output signals 312 may include any or all signals coming from the motor controller 300 to peripheral devices.

[0037] A user interface 314 is also provided such that an authorized individual can make appropriate changes to the program. It is contemplated that the various thresholds the system may check the various input signals against may be changed depending on the application. For example, for a baggage tractor that is going to be used by part time seasonal workers, the g-force threshold at which a baggage tractor may achieve prior to the system automatically cutting power to the motor may be set lower than that for baggage tractors operated by very experienced drivers. Additionally, the congestion at the facility / tarmac, or the distance the baggage tractor may need to travel to bring a load to an airplane, or the condition of the surfaces the baggage tractor may be traveling over may all be factors that can be considered in setting thresholds. It is further contemplated that weather conditions could also be considered. As such, these thresholds may be dynamically altered via a wireless connection as programmed. While it is contemplated that the user interface 314 may comprise a manual device to set the threshold values, it is contemplated that it may be desirable to have automatic wireless communication with a computer via a network connection that can automatically adjust these thresholds based on certain conditions, such as high winds or other conditions that may impact the baggage tractor in operation. For example, it is contemplated that multiple baggage tractors at an airport could have threshold values automatically adjusted airport wide when weather conditions change including snow and ice conditions. It is further contemplated that the load the baggage tractor is towing may also be taken into consideration when setting the threshold values. While a single threshold has been described, it should be noted that each threshold associated with each type of sensor could comprise multiple thresholds as which various actions are taken, or may include a range of values within which various actions are taken from the bottom of the range to the top of the range all of which can be programmable or selectable including being automatically adjusted wirelessly.

[0038] While a CPU 308 is illustrated in FIG. 3, it is contemplated that the described above program may run on a computer, a digital signal processor, a field-programmable gate array, an application-specific integrated circuit, a micro-processor, a micro-controller, or any other form of programmable hardware.

[0039] FIG. 4 depicts a view from above of a baggage tractor 404 connected to a number of baggage carts 406, 406′. The turning radius 402 is illustrated as a 90° turning angle, which results in the generation of g-forces 408 shown. The magnitude of the g-forces created will depend on the speed of the baggage tractor 404.

[0040] Referring to FIG. 5, the decision-making process of the motor controller 112 is illustrated in greater detail. As shown, accelerometer data 502 is transmitted from a peripheral device to the motor controller for decision 504 process. A negative value g-force 510 or a neutral or zero value g-force 508 will not result in an actionable decision by the safety system. A positive value g-force 506 indicates that an acceleration to a new direction is taking place. If a positive value g-force 506 is present, and the value of the g-force 516 is less than a manufacturer or installer (hereinafter “user”) defined value y (e.g., a lower threshold value), the motor controller decision 504 process ends with no change to the power being transmitted to the motor. If a positive value g-force 506 is present, and the value of the g-force 514 is between a user defined value y and a user defined value x (e.g., between the lower threshold and an upper threshold), the system will cut the power transmitted to the motor to lower the speed of the baggage tractor in a manner that is proportional to the increase in g-force. It is contemplated that this proportionality may also defined and programmed by the user. If a positive value g-force 506 is present, but outside the user defined upper bound x (e.g., over the upper threshold), the system will cut the power transmitted to the motor by a maximum amount to lower the speed of the baggage tractor.

[0041] FIG. 6 includes a schematic diagram of the accelerometer, which may comprise Measurement Specialties MEAS 4030-002-120. Also shown in FIG. 6 is the motor controller, which may comprise Curtis 1238 Model 1238-7971. The accelerometer may further be provided integral with the motor controller,

[0042] As was discussed in connection with FIG. 3, a transceiver 113 may be provided to wirelessly couple to a remote computer (not shown) to receive information relating to the threshold values saved on the storage 310 for use by the processor 308. In this manner, the thresholds may be dynamically updated even while the baggage tractor is in use. Alternatively, the system may schedule updates to the thresholds based on a date or a human resources information, such as the season or that seasonal workers may be driving the baggage tractor. In any event, the system will be completely programmable or selectable such that the safety system can be adjusted to meet changing circumstances and conditions.

[0043] In one configuration of the system, the accelerometer 202 and the motor controller 112 may be provided as a retrofit assembly that is provided as a wiring harness as illustrated in FIG. 6. Likewise, a brake pedal and a throttle pedal may be provided on the wiring harness such that a combustion engine baggage tractor may be retrofit with an electric motor and wiring harness that is directly connectable to the electric motor and the battery.

[0044] Additionally, with respect to the accelerometer, while the Measurement Specialties MEAS 4030-002-120 can effectively be used in connection with the invention, it will be understood by those of skill in the art that various other types of accelerometers may used including, for example, but not limited to a piezoelectric accelerometer (physical stress produces voltage difference, usually from vibration or fast movement), a piezoresistance accelerometer (pressure applied to sensor increases resistance), a capacitive accelerometer (change in capacitance due to acceleration, allows minute measurement of changes in accel).

[0045] Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.