Abstract:
A Pole Alarm System including an electromagnetic field sensor and collision sensors for detecting overhead power lines and physical obstructions within the intended path of a telescoping mast or utility boom device is disclosed. The present alarm system includes a mast-mounted housing containing the sensors and a microprocessor-based control unit which interprets the output signals of the sensors and provides both audible and control feedback to a safety control module in the vehicle to alert the operator of impending contact and to automatically stop the movement of the mast. The alarm housing also features a light source which provides illumination in the direction of movement of the mast to assist in positioning thereof. The light source also functions as a heating element to prevent the accumulation of ice on the housing which would detrimentally affect the performance of the system. The alarm housing also includes a plurality of Tilt sensors which monitor the orientation of the mast to prevent mast extension if the device deviates from an acceptable range of operation. A system integrated safety control module mounted in the vehicle provides self-test functions and an error code display to alert the operator to the cause of an alarm signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of application Ser. No. 09/440,071 filed Nov. 15, 1999, now U.S. Pat. No. 6,133,841, which was a continuation of application Ser. No. 09/165,380 filed Oct. 2, 1998, now U.S. Pat. No. 6,104,305. 
     This Application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Application No. 60/065,803 filed Nov. 14, 1997 by Uwe L. Beckmann and Robert U. Beckmann for Pole Alarm. 
    
    
     BACKGROUND OF INVENTION 
     FIELD OF INVENTION 
     The present invention relates generally to alarm systems and, more particularly, to a collision avoidance alarm for a telescoping mast. 
     Telescoping masts of the type including a plurality of extensible, interconnected sections operated by pneumatic, hydraulic, or mechanical power are well known to those skilled in the art. For example, such telescoping masts are used extensively in the broadcast industry to elevate antennas for remote transmission of audio and video signals. Such a telescoping mast is also utilized on utility repair trucks having elongated boom including a so called “cherry picker” that is used by public and private utility maintenance crews to reach elevated power, cable, and telephone transmission lines. Similarly, the present Pole Alarm system is also suitable for use on ladder trucks, cranes, hoists, and other related equipment. 
     Remote broadcast antennas mounted on telescoping masts or poles must often be rapidly deployed under severe weather conditions as might be encountered by a television or radio news crew while reporting on a natural disaster. Similarly, utility crews must elevate maintenance workers to reach and repair damage to power and telephone lines often during inclement weather and at night. 
     Although few problems are encountered while raising such a mast in open areas having good visibility, the maintenance workers&#39; life and equipment is subject to an extreme risk when overhead electrical transmission lines and/or physical obstructions are encountered particularly at night or during other poor visibility conditions. In a number of instances contact with electrical wires and collisions with overhead obstructions have resulted in the injury or death of personnel and extensive damage to equipment. 
     Thus, there is a need for an alarm device to warn the operator of such a telescoping mast or boom type device of an impending collision with overhead power lines or other potentially dangerous obstruction before actual contact occurs. Such a warning would significantly reduce personal injuries to the operator and damage to the equipment caused by a collision. 
     SUMMARY OF THE INVENTION 
     After much study of the above described problems, the present invention has been developed to provide a Pole Alarm System which will alert the operator of a boom truck or other telescoping mast apparatus of impending contact with an overhead power line or other potentially dangerous overhead structure before actual contact occurs. 
     The present Pole Alarm System includes a housing which is mounted on the uppermost portion of the-mast or boom to be monitored including as least two separate sensing devices capable of detecting an electrical field generated by an overhead power transmission line and of detecting physical obstructions within a specified proximity of the housing using an ultrasound transducer. 
     The alarm housing also includes a light source or so-called Lookup Light which illuminates the area of intended movement of the mast to enhance the operator&#39;s ability to safely control the equipment to which the alarm housing is attached. 
     In addition, the present alarm system includes a plurality of tilt sensors which monitor the orientation of the mast relative to a desired level condition which will prevent mast extension if it is tilted or leaning. 
     Upon detection of an overhead power line or physical obstruction, the Pole Alarm System provides both audible and control feedback to a control module within the vehicle to alert the operator of impending contact and to quickly stop the movement of the mast or boom. 
     The range of detection provided by the present alarm system is designed such that the audible alarm activates in sufficient time to permit the operator to manually halt the movement of the mast or boom and to provide a control signal to the mast&#39;s electrical controller to automatically stop movement into the hazardous zone. 
     In view of the above, it is an object of the present invention to provide a Pole Alarm System for use on a telescoping mast apparatus such as a utility boom truck that will warn the operator of impending contact with an overhead power line or other physical obstruction. 
     Another object of the present invention is to provide a Pole Alarm System having at least two separate sensor devices capable of detecting the presence of an electrical field and/or capable of detecting physical obstructions by the use of ultrasound or other technologies. 
     Another object of the present invention is to provide a Pole Alarm System including a light source to illuminate the area of intended movement of the mast to enhance the operator&#39;s ability to safely control the equipment. 
     Another object of the present invention is to provide a Pole Alarm System including tilt sensors capable of detecting the orientation of the mast relative to a level condition to ensure proper operation of the device. 
     Another object of the present invention is to provide a Pole Alarm System capable of providing both audible and control feedback to alert the operator of impending contact and to automatically stop movement of the mast into a hazardous zone. 
     Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a diagrammatic view of the Pole Alarm housing of the present invention mounted on a telescoping mast structure; 
     FIG. 2 is an enlarged, side elevational view of the Pole Alarm housing showing the arrangement of components therein; 
     FIG. 3 is a schematic diagram showing the circuitry interconnecting the AC detector, the Collision Detector, the Lookup Light and the tilt sensors of the present alarm system; 
     FIG. 4 is a schematic diagram showing the interconnection of the Pole Alarm system&#39;s circuitry to the external audible alarm, lamps, switches, and valves; 
     FIG. 5 is a schematic diagram showing the interconnection of the microprocessor circuit board to the components in the alarm housing; 
     FIG. 6 is a schematic diagram of the Collision Detector of the present system showing the components and circuitry thereof; 
     FIG. 7 is a schematic diagram of the AC detector of the present invention showing the components and circuitry thereof; 
     FIG. 8 is a schematic diagram of the control circuitry and components of the Lookup Light of the present alarm system; 
     FIG. 9 is a schematic diagram of the microprocessor circuit board of the present alarm system; and 
     FIG. 10 is a front elevational view of the safety control module of the present system. 
    
    
     DETAILED DESCRIPTION OF INVENTION 
     With further reference to the drawings there is shown therein a view of the pole alarm housing, indicated generally at  100 , disposed on a telescoping mast  25  of the type used on a boom truck. There is shown in FIG. 2 an enlarged view of the pole alarm housing  100  and the components contained therein including the AC (alternating current) detector antenna, indicated generally at  10 , the Collision detector unit, indicated generally at  11 , a light source or so-called Lookup Light, indicated generally at  12  and the integrated control unit, indicated generally at  13 . 
     It will be understood that the housing  100  must be disposed at the highest point of the telescoping mast  25  as shown in FIG.  1  and directed generally upwardly in its functional position. There must be no obstructions to either the AC detector  10  or the collision detector  11  for the present alarm system to function properly. 
     The AC detector antenna  45  protrudes above the housing  100 . The halogen spotlight bulb  12 ′ of the Lookup Light  12  is located within the housing  100  for protection. The Collision Detector  11  is side mounted. The Control Unit  13  is located inside the housing  100  to shield and protect the circuitry from the environmental elements. The Tilt sensors  59  are mounted in the Control Unit  13  circuit board. 
     In an alternative embodiment (not shown) multiple AC and Collision Detectors  10  and  11  as described hereinabove are positioned to provide detection of an electrical power line or a physical obstruction in any one of three axes relative to the housing. 
     Referring now to FIG. 3 there is shown therein a schematic diagram of the control circuitry for the AC detector antenna  10 , the Collision detector  11 , and the lookup light  12 . Also illustrated in FIG. 3 are the tilt sensors  59  which are located in the housing  100 . 
     Referring now to FIG. 4, the control unit  13  is connected to +12 Volts (DC) through a main power disconnect switch  14  and fuse  15 . A second power lead  16  connects to the vehicle ground  17 . 
     The audio External Alarm output  18  applies a signal to the audible device  19 , which in this case illustrated as a piezo-resonator upon the detection of a possible safety hazard. 
     The Status External Output  20  operates a lamp  21  to provide an indication of the status of the alarm. A second lamp  22  is lit by the signal from the Collision external output  43  upon detection of an object with which the mast or boom is about collide. A third lamp  23  is lit by the signal from the AC External output  51  upon detection of the presence of a high voltage line. 
     The audible device  19 , the lamps  21 ,  22 ,  23 , and external switches  24  are each connected to a common +12 Volts (DC) output Control Com.  25 . on the control unit  13 . The external switches  24  are connected to the Mast Raise input  26  and Mast Lower input  27  to control the movement of the mast or boom  26 . 
     When switches  24  are activated, the corresponding pneumatic or hydraulic valve  28  associated with the mast or boom  26  and connected to the Valve Air Output  29  and the Valve Vent Output  30  are energized as appropriate to raise or lower the mast or boom. 
     The control system as described hereinabove also permits the Control Unit  13  to override the manual operation of the mast or boom  26  and halt the movement thereof before a hazardous power line or obstruction is contacted. The Control Unit  13  connects through multiple signal conductors  31  to the AC detector  10  and the Collision detector  11 . 
     Referring now to FIG. 5 there is shown therein a more detailed diagram of the interconnection of the Control Unit  13  with the AC detector  10 , the Collision detector  11  and the Tilt sensors  59  of FIG.  3  and the valves  28  of FIG.  4 . 
     As illustrated in FIG. 5 EMI filters  33  are provided on each signal input i.e. COL signal  61 , TX  37 , TILT  60 , and AC signal  62  to the Control Unit  13  to minimize detection of the false electrical signals. 
     Also shown in FIG. 5 is a temperature sensing element  34  with its associated voltage comparator  35  which is configured to signal the Control Unit  13  when the ambient temperature of the alarm housing  10  exceeds a predetermined level. 
     The voltage comparator  35  is connected to a LAMP input  36  on the Control Unit  13 . Serial communications data are received by the Control Unit  13  on the TX input  37  and transmitted on the TxD output  38 . 
     Zener and standard diodes  39  are provided to protect the Control Unit  13  from damage resulting from excessive or reverse polarity voltages inadvertently applied to the Control Unit  13 . 
     A MOS field-effect transistor (MOSFET)  40  is utilized to interface the Control Unit  13  to the relay  41  which, in turn, provides control voltage to the external pneumatic or hydraulic valves  28 . The status of the Tilt sensors  59  is monitored through the Tilt input  60 . 
     Referring now to FIG. 6 there is shown therein a preferred embodiment of the control circuitry for the ultrasonic Collision detector  11 . The output from the Collision detector  11  is connected to the TX, TXFILT, +5V, and COL signal terminal connector indicated generally at  44 . The ultrasonic collision detector  11  detects objects that are within 1 to 8 feet of the alarm housing  100  and outputs a control signal to the vehicle&#39;s mast control device (not shown) to halt the movement of the mast. 
     Since such ultrasonic collision detectors as a separate device are well known to those skilled in the art, further detailed discussion of the same is not deemed necessary. 
     Referring now to FIG. 7 there is shown therein a schematic diagram of the AC detector  10  of the present alarm system. The AC detector  10  detects the presence of AC (alternating current) voltage through its associated antenna  45 . Such electrostatically induced signal is amplified by a force-effect transistor (FET)  46  and filtered by multiple stages of filtering circuitry, indicated generally at  47 . 
     In the preferred embodiment the AC detector  10  is capable of sensing the presence of a 7200 Volt 60 Hertz electrical transmission line at a minimum distance of 8 feet. This distance is sufficient to provide ample warning for the operator of the mast or boom to halt the travel thereof towards the power line or to provide an electrical signal to the mast positioning control device (not shown) of the vehicle to automatically stop the movement of the mast thereby avoiding a collision. The output from the AC detector  10  is interconnected to the Control Unit  13  through the AC signal terminal  48 . 
     Control of the Lookup Light  12  is accomplished with the circuitry illustrated in FIG. 8. A negative temperature coefficient (NTC) device  49  responds to the ambient temperature within the alarm housing  100 . The voltage resulting from voltage division between a thermally stable resistor  50  and the NTC device  49  is monitored with a pair of voltage comparators  35  in a window configuration. 
     If the ambient temperature drops below a predetermined threshold level, as would occur with icing of the alarm housing  100 , the Lookup Light  12  illuminates and serves as a heater element thereby melting the ice and keeping the present system operational. Should the ambient temperature rise above a second predetermined threshold level, as would occur with prolonged operation of the halogen light, the Lookup Light  12  extinguishes to permit the housing  100  to cool before being damaged by excessive heat. 
     Upon detection of an electrical or physical obstruction within the range of either sensor, audible and visible alarms are activated to alert the person operating the mast positioning system of the imminent collision. The Lookup Light  12  functions to provide illumination to assist the operator in guiding the mast to a safe position. 
     Referring now to FIG. 9, a microprocessor circuit board, indicated generally at  52 , provides interpretation of and response to signals generated by the AC detector  10  and the collision detector  11 . In the preferred embodiment, this conventional microprocessor configuration includes an 8031-type microprocessor  53 , an external CMOS latch  54 , and an erasable programmable read-only memory- 55 . 
     Because the microprocessor  53  and its associated circuitry are low voltage, low current devices, they are unable to directly drive external relays, valves, or other higher current devices. Interconnection and proper drive levels are achieved with an array of additional transistors, indicated generally at  57 , as shown. 
     Visual status indications i.e. (AC, STATUS, COLLISION, TILT) are provided by light emitting diodes  56 . 
     Power-on reset for the microprocessor  53  is provided by a watchdog circuit  58  specifically designed to monitor the operating voltage of the microprocessor circuit board  52  and reset the microprocessor  53  as necessary to start and maintain reliable operation. 
     The basic operation of the Pole Alarm System and the operating relationships of the respective sensors will now be described. In order to operate the present alarm system, the housing  100  containing the sensors is installed at the highest point of the mast or boom using suitable attaching hardware such that the AC detector  10  projects upwardly as shown in FIG.  1 . It is critical to the operation of the present system that there be no obstructions to either the AC detector antenna  45  or the Collision detector  11  which projects from the side of the housing  100 . 
     A 6-conductor shielded cable  65  not to exceed 100 feet in length and a wire gauge no smaller than 16 gauge is utilized to connect the Pole Alarm housing  100  to the safety control module, indicated generally at  66  as shown in FIG. 10, which is mounted inside the vehicle. The safety control module  66  should be mounted to allow the operator an unobstructed view of the warning indicators  68 - 71  while operating the mast. 
     Of course, the switches for extension and retraction of the mast for movement of the boom as well as the control valves should be wired as specified in the vehicle wiring schematic. 
     The Pole Alarm System requires 12.6 Volts DC nominal (actual 10.6 Volts to 20 Volts) at a maximum current not to exceed S amperes. A fuse-protected circuit of 8 amperes should be provided. 
     Even though the Pole Alarm has robust noise filtering on its power input circuitry, some installations with extreme electrical noise from other devices may necessitate additional filtering of the power input. Since installations vary considerably from vehicle to vehicles it is the installer who must verify proper operation of the safety control module  66  under all conditions. 
     After installation of the Pole Alarm System is completed, power is turned on using the main power switch  67  on the safety control module  66 . The present system is designed to perform a comprehensive system self-test requiring approximately 8 seconds. When the self-test is complete and passes, the Ready Status indicator  68  will glow “green” continuously. This visual indicator signifies that the system appears to be working properly and that extension of the mast or boom may proceed. 
     If the self-test fails, an error indicating code will be displayed by the System Ready indicator  68 . The failure codes are as follows: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 1 blink every 10 seconds 
                 AC detector failure 
               
               
                   
                 2 blinks every 10 seconds 
                 AC detector failed to clear 
               
               
                   
                 3 blinks every 10 seconds 
                 collision detector failure 
               
               
                   
                 4 blinks every 10 seconds 
                 collision detector failed to clear 
               
               
                   
                 5 blinks every 10 seconds 
                 extend switch failure 
               
               
                   
                   
               
             
          
         
       
     
     Assuming the self-test passes, the Pole Alarm System is in a monitoring status. The mast-mounted Lookup Light  12  will be illuminated and there may be an occasional flash of the AC power indicator  69  on the control unit. The rate at which the AC power indicator  69  flashes is a measure of the signal strength of a nearby AC power source. After making a thorough inspection of the overhead and surrounding area, the mast or boom  26  may be extended using the vehicle&#39;s mast controls (not shown). 
     If during the monitoring state the present Pole Alarm senses a possible collision or a dangerous AC electric field, an alarm condition is triggered. The safety control module  66  will sound an audible alarm via speaker  72  and will show the operator the cause of the alarm condition. A rapidly flashing AC power indicator  69  signifies the presence of a strong AC electric field. A flashing Collision indicator  70  signifies a possible collision with a power line or other physical obstruction. A flashing Tilt indicator  71  indicates an unbalanced condition of the mast or an unlevel condition of the vehicle or both. 
     During either alarm condition a further extension of the mast or boom is automatically blocked, and the System Ready indicator  68  goes dark. If after 5 seconds the offending alarm condition is removed, extension of the mast is again allowed. Of course, it is possible to retract the mast or boom at any time during operation. 
     If no alarms occur and if no further attempt to raise the mast or boom for approximately 15 minutes, the present alarm system will enter a resting state. AC monitoring will continue; however, the Lookup Light  12  will turn off and the operation of the Collision detector  11  will cease. 
     During situations of extreme cold, the mast-mounted Lookup Light  12  may illuminate whenever the main power switch is in the “on” position. This illumination will help to minimize ice or snow buildup on the alarm housing  100  by raising the temperature thereof The AC detector  10  and the Collision detector  11  must be kept free of ice and snow for proper operation. 
     Conversely, prolonged operation of the mast-mounted Lookup Light  12  may cause the alarm housing  100  to become overheated, in which case the Lookup Light  12  will be automatically disabled. The light  12  will again be eliminated when the alarm housing&#39;s temperature returns to a predetermined normal operating temperature. However, at no time should the AC power or Collision warnings be affected. 
     From the above it can be seen that the Pole Alarm System of the present invention provides an improved measure of safety for the operator of a telescoping mast or boom truck or other related equipment by providing both audible and control feedback to alert the operator of impending contact with dangerous overhead power lines or physical obstructions. 
     The range of detection provided by the alarm system is designed such that the audible alarm activates in sufficient time to cause the operator to manually halt the movement of the mast or boom and to provide a control signal to automatically stop the movement of the mast into the hazardous zone. 
     The terms “upper”, “lower”, “side” and so forth have been used herein merely for convenience to describe the present invention and its parts as oriented in the drawings. It is to be understood, however, that these terms are in no way limiting to the invention since such invention may obviously be disposed in different orientations when in use. 
     The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of such invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.