Title of Invention

"AN IMPROVED REMOTE CONTROL SYSTEM FOR OPERATING AN OVERHEAD CRANE IN STEEL PLANTS "

Abstract

An improved remote control system for operating an overhead crane in steel plants, characterised in that, the system comprises : (i) a palm-held operators console having twelve switches and an antenna for generating digital switch signals and transmitting the same over a VHP carrier wave; (ii) a VHP radio receiver located in the cabin attached to the crane structure for receiving the signals transmitted by the operator's console; and (iii) a programmable controller located in the cabin, having an input module for storing the digital switch signals received from the output of receiver in a processor module, a software,programmed in the logic, such as herein described, programmed by an IBM-PC personal computer as programming terminal with printer for documentation, an output module acting as an electrical interface for controlling the direction of and speed of motion of each of the four motor drives of the crane, respectively for long travel, cross travel, hoist travel and auxiliary travel thereof, and at least one display and alarm unit located in the cabin for visually displaying the direction and speed of motion of each of the four motor drives of the crane, and raising alarm signals in case of non-functioning or mal-functioning of the control system, the said components being arranged to operate in an inter-dependent manner.

Full Text

The present invention relates to an improved remote control system for operating an overhead crane in steel plants. The existing control system of an overhead EOT crane requires one person to be stationed in a cabin attached to the crane structure to operate the crane and another person stationed on the shop floor to hook the sling connected to the material to be handled with the crane and to provide a signal for the person in the cabin for operating the crane, the cabin being located at a height of about 10 m above the shop floor, There are four motor drives powered by 3-phase, 415 V AC supply, speed of which are controlled by 'Joy Sticks' i.e. master controllers provided in the cabin and electrically connected with the motor drives through cables. The drawbacks of the existing system are : (a) in the absence of correct understanding between the person stationed on the shop floor for sending the signal for operation, and the person stationed in the cabin for operating the crane, serious accident may take place, (b) both the said persons are required to work continuously in inconvenient environment of the shop over a prolonged period and (c) two persons are required to be engaged for operation of the crane with resultant increase in the cost of operation. The objective of the present invention is to provide a control system for operating an overhead crane in steel plants operable from a distance of upto about 100 m from the crane structure without having any cable connection between the operator and the equipment in the cabin for controlling the motor drives of the crane. - 2 - The other objective is to reduce the operating cost of the crane. The invented remote control system comprises a palm-held operator's console containing a transmitter for transmitting digital switch signals on a very high frequency (VHF) carrier wave, a receiver to receive the transmitted digital switch signals, a programmable controller to accept the digital switch signals from the receiver and store the same in a random access memory (RAM), programmable read only memory (EEPROM) containing control program for crane operation and an electrical interface to transfer the digital switch signals from the programmable controller to the joysticks or master controllers in the cabin through relays, contactors and switches, and at two display and alarm units located one in either side of the cabin to display visually the operational status of the motions, which can be seen from a distance of about 100 m and generate alarms in case of failure or malfunctioning of the crane in remote operation. Thus the invention provides an improved remote control system for operating an overhead crane in steel plants, characterised in that the system comprises : (i) a palm-held operator's console having twelve switches and an antenna for generating digital switch signals and transmitting the same over a VHF carrier wave; (ii) a VHF radio receiver located in the cabin attached to the crane structure for receiving the signals transmitted by the operator's console; and (iii) a programmable controller located in the cabin, having an input module for storing the digital switch signals received from the output of receiver in a processor module, a software,programmed in the logic, such as herein described, programmed by an IBM-PC personal computer as programming terminal - 3 - with printer for documentation, an output module acting as an electrical interface lor controlling the direction of and speed of motion of each of the four motor drives of the crane, respectively for long travel, cross travel, hoist travel and auxiliary travel thereof, and at least one display and alarm unit located in the cabin for visually displaying the direction and speed of motion of each of the four motor drives of the crane, and raising alarm signals in case of non-functioning or mal-functioning of the control system, the said components being arranged to operatre in an inter-dependent manner. The invented control system is described fully and particularly without restricting the scope of the invention in any manner with reference to accompanying drawings in which - Figure 1 is a schematic diagram showing the interconnection between the main functional units of the system. Referring to Fig. 1, the invented control system comprises (i) a palm-held operator's console (1) containing twelve push-button sv/itches (2), the operation of which produces digital signals which are transmitted as modulated VHF signals through antenna (3) at a carrier frequency of 335.7125 MHZ; (ii) a VHF radio receiver (4) tuned to receive the modulated VHF signals, free from any noise signals, and to reproduce the digital switch signals in the cabin attached to the crane structure, where the receiver is located; (iii) a programmable controller (5), located in the cabin and connected to the output of the receiver through input module, to store the digital switch signals in a processor module, consisting of a random access memory (RAM) and a programmable read only memory (EBPROM) acting - 4 - as a back-up memory for the software grogram and data table in the processor module; (iv) an output module acting as electrical interface (6) of the programmable controller for supplying open collector outputs to relays; contactors and switches used in the cabin to control the operation of the four motor drives (7, 8, 9 and 10) of the crane respectively for long travel, cross travel, hoist travel and auxiliary travel; (v) an IBM-PC personal computer as programming terminal (11) with a printer for hard copy •» documentation (12) for programming the software in the programmable controller, having mainly four modules one each for safety check, motion direction selection, motion speed selection and motion speed monitoring; and (vi) at least one display and alarm unit (13) located in the cabin and connected to the programmable controller to display visually the motion direction and motion speed of the four motor drives of the crane and to raise alarm signals in case of the failure or mal-functioning of the control system. The logic followed for programming the four modules of the software is described below. The module for safety check receives the digital switch signals from the receiver under two types of safety constraints, namely, the integrity rules for 'safe start up' and the diagnostic rules for 'continuous evaluation' of safe operation, and stores the signals in two sub modules, termed respectively as 'interlock' and 'diagnostic' submodules. After the digital switch signals have been checked for safety and logical requirements in the module for safety check, these are accepted by the module for motion direction selection - 5 - for selecting one of the two directions of motion, termed 'positive1 and 'negative', as needed, and locking the selected direction once the motion begins, which can be changed only when the motion stops. After the motion direction has been selected in the module for direction selection, any of the four different speeds of motion, are selected either in steps or directly, by the module for motion speed selection and kept 'locked', if required, along with the selection of the deceleration and braking operations required. After selection of the direction and speed of motion by the modules for direction and speed selections, the module for motion speed monitoring receives the output signals of both the said two modules for direction and speed selection, keeps the output signals of direction selection module locked and monitors the output signals of the speed selection module continuously as long as the crane is in motion. The crane can be operated by a single person carrying the palm-held console and moving from one place to another on the shop floor upto a distance of about 100 m from the crane structure and hence at a reduced cost of operation and without the need for stationing another person continuously in the inconvenient environment near the crane structure, and with reduction in the chances of accidents caused by lack of correct understanding between one person stationed in the cabin for operating the system and another person stationed on the shop floor for hooking the sling connected with the material to be handled, as in the existing control system. - 6 - We Claim ;- 1. An improved remote control system for operating an overhead crane in steel plants, characterised in that the system comprises : (4) a palm-held operator's console (1) having twelve sv/itches (2) and an antenna (3) for generating digital switch signals and transmitting the same over a VHF carrier wave; (ii) a j VHP radio receiver (4) located in the cabin attached to the crane structure for receiving the signals transmitted by the operator's console; and (iii) a programmable controller (5) located in the cabin, having an input module for storing the digital switch signals received from the output of receiver (4) in a processor module, a software,prograramed in the logic, such as herein described, programmed by an IBM-PC personal computer as programming terminal (11) with printer for documentation (12), an output module acting as an electrical interface (6) for controlling the direction of and speed of motion of each of the four motor drives (7, 8, 9 and 10) of the crane, respectively for long travel, cross travel, hoist travel and auxiliary travel thereof, and at least one display and alarm unit (13) located in the cabin-for visually displaying the direction and speed of motion of each of the four motor drives of the crane, and raising alarm signals in case of non-functioning or mal-functioning of the control system, the said components being arranged to operate in an inter-dependent manner, 2. The system as claimed in claim 1, wherein both the operator's console and the VHF radio receivers are tuned to the VHF carrier wave of frequency 335.7125 MHZ. - 7 - 3. The system as claimed in claim 1 or 2, wherein the programmable controller is provided with a processor module having random access memory (RAM) and a programmable read only memory (EEPROM) acting as a back up memory for the software program and data table. - 8 - A. An improved remote control system for operating an overhead crane, substantially as herein described and illustrated in the accompanying drawings. An improved remote control system for operating an overhead crane in steel plants, characterised in that, the system comprises : (i) a palm-held operators console having twelve switches and an antenna for generating digital switch signals and transmitting the same over a VHP carrier wave; (ii) a VHP radio receiver located in the cabin attached to the crane structure for receiving the signals transmitted by the operator's console; and (iii) a programmable controller located in the cabin, having an input module for storing the digital switch signals received from the output of receiver in a processor module, a software,programmed in the logic, such as herein described, programmed by an IBM-PC personal computer as programming terminal with printer for documentation, an output module acting as an electrical interface for controlling the direction of and speed of motion of each of the four motor drives of the crane, respectively for long travel, cross travel, hoist travel and auxiliary travel thereof, and at least one display and alarm unit located in the cabin for visually displaying the direction and speed of motion of each of the four motor drives of the crane, and raising alarm signals in case of non-functioning or mal-functioning of the control system, the said components being arranged to operate in an inter-dependent manner.

Documents:

00086-cal-1999 abstract.pdf

00086-cal-1999 assignment.pdf

00086-cal-1999 claims.pdf

00086-cal-1999 correspondence.pdf

00086-cal-1999 description (complete).pdf

00086-cal-1999 drawings.pdf

00086-cal-1999 form-1.pdf

00086-cal-1999 form-2.pdf

00086-cal-1999 form-3.pdf

00086-cal-1999 form-5.pdf

00086-cal-1999 letters patent.pdf

00086-cal-1999 p.a.pdf