Description:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the field of anti collision systems, more particularly to a laser based anti collision system for twin boom stacker machines in raw material handling plant.
BACKGROUND OF THE INVENTION
In RMHP (Raw material handling plant, raw materials are stacked according to their type & grade by giant machines called stacker-reclaimers. These machines pick up the raw materials and deposit them on conveyor belts using continually rotating 'buckets'. The conveyors then deposit the material according to grade.

The prior art that discloses works on anti-collision system are:
CN112850501Bdiscloses an automatic anti-collision method and system for a tower crane, wherein the method comprises the following steps: building a three-dimensional model of a construction site according to a preset model building strategy; updating the three-dimensional model of the construction site with fixed frequency and the grid coordinates of the external outline of the existing site at the current moment; when the tower crane starts to lift, acquiring coordinates of lifting points of objects and coordinates of preset reaching points; planning an operation path for the tower crane according to a preset path planning strategy and a construction site three-dimensional model, and generating corresponding operation parameters.
CN107285206Bdisclosesa kind of collision-proof methods based on derrick crane collision prevention early warning system, the construction site of derrick crane is invented into the image spot of controllable operation and is integrated in the anticollision automatic control module of correspondence system to realize anticollision, specifically: by include in construction site opposite barrier, target boom, relevant environment parameter attribute map to image spot one by one；After the anti-collision algorithm for moving across image spot occurred in construction site calculates, the control instruction for executing construction site movement is issued.
US9738494B2disclosesa safety lighting system for an overhead crane comprising a laser generator capable of generating a laser signal; and a crane control system having a programmable logic circuit; wherein the laser generator is integrated with the crane control system; and wherein the laser generator is operable to project a laser signal onto a surface corresponding to the position of the crane or crane components and a method of using the safety lighting system to determine when an object has crossed into a designated safety zone.
CN105253635Bdisclosesan automatic unstacking, package stacking and loading all-in-one machine and a working method thereof. The automatic unstacking, package stacking and loading all-in-one machine comprises an unstacking unit, a conveying unit and a conveying and a package stacking unit. The unstacking unit is used for lifting a whole package stack, making the whole package stack incline and sequentially distributing all layers of packages in the whole package stack to the conveying unit layer by layer from the top layer. The conveying unit conveys all the packages to the conveying and package stacking unit. The conveying and package stacking unit conducts package stacking and loading on all the packages. The slope slipping control type automatic unstacking technology is adopted for the unstacking part.
CN107879260Bdiscloses a kind of tower crane collision avoidance system based on BIM, including monitor terminal, is arranged at control and command center；Several panorama camera devices carry out information exchange with the monitor terminal, and each described panorama camera device correspondence is mounted on a tower crane near target construction, to the carry out panoramic shooting of the target construction；Wherein, the cockpit of the tower crane is provided at least such as lower unit: tower crane communication unit carries out information exchange with the monitor terminal, for the photo of the movement position information of the tower crane, shooting and corresponding identity identification information to be transmitted to the monitor terminal.
Stackers normally travel on a rail between stockpiles in the material yard. A stacker can usually move in at least two directions: horizontally along the rail and vertically by luffing (raising and lowering), its boom. Luffing of the boom minimizes dust by reducing the distance that material needs to fall to the top of the stockpile. The boom is luffed upwards as the height of the stockpile increases while the stacker traverses the yard horizontally to make the material bed.

Stacker machines are used in bulk material handling. Its function is to pile bulk material such as iron ore, limestone, sinter and dolomite on to a stockpile. A reclaimer can be used later to recover the material.

Stackers are used to stack in different patterns, in most cases, the stacker travels along the length of the stockpile adding layer upon layer of material. The stacker moves on a rail track, enabling it to move around the material yard as required. For this purpose, traction motors controlled by VFD(Variable frequency drive) are used. Stackers are electrically powered by way of a trailing cable. There are basically two types of cable trailing: power cord rotating drum (PCRD) and control cable rotating drum (CCRD). Pendulum adjustments are made to ensure the proper alignment of these cables while the stacker is travelling. All the controls are in a controller/operator cabin above the boom conveyor or boom.

As the stacker moves continuously dumping the material, a pile is built up, but due to uneven material deposition the top layer of the pile becomes uneven. Due to which while traversing, the boom of the stacker is required to be manoeuvered very carefully by the operator in order to avoid collision with the material pile. For this the operator has to constantly look out of his cabin window or keep someone else near the edge of the railing to keep track of the boom movement. Sometimes inadvertently owing to fatigue or carelessness, the operator is unable to do the required boom adjustments and the structure collides with the material pile leading to breakdowns and damage to the stacker boom.

Every instance of this collision gives rise to a major breakdown causing loss of production hours, engagement of lots of manpower in repair work and, progressive weakening of the boom structure itself.

There has thus been a need to devise some system to automatically avert such collisions and nullify the aspect of human error in a reliable manner so that the machine could be operated safely without breakdowns arising out of collision with material.
OBJECT OF THE INVENTION
It is an object of the present invention to overcome the shortcomings of the prior art.

It is an object of the present invention to provide a laser based anti collision system by which collision of moving/traversing structures such as stackers and reclaimers with raw materials can be avoided automatically in a reliable manner,so as to nullify the chances of any collision occurring due to human error or careless operation.

Yet another object of the present invention is to provide safety of operation to the cabin operator in the stacker machine by avoiding collisions that can cause excessive vibrations or machine derailment.

Another objective of the invention is to protect the movable boom structure against structural damages owing to collisions with the material thereby prolonging its usable life.

Yet another object of the present invention is to prevent loss of production hours that occur due to various major or minor instances of collision of stacker booms with raw materials. There by enhancing productivity of the machine and the plant.
Yet another object of the present invention is to avoid unnecessary engagement of manpower in repair and maintenance work which is unproductive and that could be avoidable by avoiding damages to the structure happening due to collisions in the first place.

Still another object of the present invention is to provide low cost yet reliable and effective means of avoiding collisions of the stacker boom with materials thereby providing a cost effective means of enhancing productivity of the machine.

These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION
The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

In one aspect of the present invention there is provided an anti-collision system for twin boom stacker machines, the system comprising:
a laser-based distance sensor configured to be mounted on a moving structure, wherein the moving structure is selected from the group consisting of a boom of a crane and a stacker machine; and
an auxiliary relay circuit configured to automatically control a main traverse motor circuit of the stacker machine based on triggers received from the laser-based distance sensor.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 depicts twin boom stacker used to make material bed of an anti-collision system for twin boom stacker machines in accordance with an embodiment of the present invention.

Figure 2 depicts schematic representation of the dimensions of laser sensor of an anti-collision system for twin boom stacker machines in accordance with an embodiment of the present invention.

Figure 3 depicts schematic representation of time of flight based pulse ranging technology method for determining distance of an anti-collision system for twin boom stacker machines in accordance with an embodiment of the present invention.

Figure 4 depicts schematic representation of electrical connection diagram of an anti-collision system for twin boom stacker machines in accordance with an embodiment of the present invention.

Figure 5 depicts schematic representation of wiring diagram of an anti-collision systemfor twin boom stacker machines in accordance with an embodiment of the present invention.

Figure 6 depicts schematic representation of biasing circuit for auxiliary relay R1 of an anti-collision system for twin boom stacker machines in accordance with an embodiment of the present invention.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may not have been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding, but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments belong. Further, the meaning of terms or words used in the specification and the claims should not be limited to the literal or commonly employed sense but should be construed in accordance with the spirit of the disclosure to most properly describe the present disclosure.

The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof.

The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown.

In one embodiment present invention describes an anti-collision system for twin boom stacker machines, the system comprising:
a laser-based distance sensor configured to be mounted on a moving structure, wherein the moving structure is selected from the group consisting of a boom of a crane and a stacker machine; and
an auxiliary relay circuit configured to automatically control a main traverse motor circuit of the stacker machine based on triggers received from the laser-based distance sensor.

In an another embodiment the present invention describes the sensor is able to detect any obstructions, in this case pile of raw material,that comes in its proximity in turn triggering the control circuit to break the supply to the main traverse motor, thus halting the advance of the stacker boom before it collides with the material. Thus enabling safe operation of the equipment and eliminating long, unplanned maintenance work that was required to be done whenever the stacker boom sustained damage due to collisions with the pile of material.

Figure 1 shows a stacker machine that traverses throughout the length of a material bed to convey and deposit material forming a continuous bed of the material.The main objective of a material handling system is to stack iron ore, sinter, limestone and other bulk materials in piles, or to reclaim and move them from storage to another location. The operation of building a pile is called “stacking,” and removing and relocating operations are called “reclaiming.”

The present system is electrically-powered. The power source is centrally located in between the two rails on which the equipment travels. When it moves forward or backward, the electric cable alternately stretches out or rolls up. An electrical room is in place to control the motors for moving and slewing operations, and to control the winch.Material flows by way of the boom - the “main street” of the system - for stacking and reclaiming. The conveyor inside the square framework travels in a loop in order to transport material. For reclaiming, the system drops material from the center of the portal onto the conveyor that runs on the ground between two rails.

There are two ways to keep the boom in place and to raise/lower it: one is to suspend the boom with cables and move it using an electric winch; and another is to install a luffing cylinder at the base of the boom. The tripper conveys materials brought from another location up to the boom for stacking and moves large volume of material in a short time.

Accurate detection of pile edges is a key constraint in maneuvering the stacker boom while trying to optimize the material deposition and bed formation.There is always a danger of misjudgement on the part of the operator in this regard which leads to collisions of the boom with the material. Depending on the intensity of such collisions the boom structure can get badly entangled with the material pile and suffer heavy damage itself.

So, the present invention is a system to detect an impending collision beforehand by placing/mounting a laser sensor on the traversing face of the stacker boom which helps detect an approaching obstruction and triggers a relay circuit to open the main traverse motor circuit of the stacker itself, thus, stopping the onward movement and avoiding the collision of the structure.

Laser sensor:
A laser sensor in the present invention is used as a distance measurement value recorder working with laser technology and turning the physical measured value into an analogue electrical signal. This means that the laser sensor is conceived for contactless measurement. The laser sensor works based on the time of flight (TOF) principle based on pulse ranging technology. Thus with the help of a laser sensor one can measurea distance’s length and positions, without any contact. This happens at a high resolution. Laser sensors also dispose of various linearities, in addition to the various resolutions.

Due to the integrated intelligent signal analysis, the laser sensor can deliver an exact result. And this irrespective of the colour of the respective surface by way of the emitted laser beam that is extremely focused, the laser sensor is able to perform finer measurements than devices based on light diodes.

Laser-based distance measurement often serves as a way of positioning parts, and measuring the dimensions of objects like boxes. There are three common technologies behind laser-distance measurement: optical triangulation, phase correlation, and true time-of-flight (TOF) technology.

Pulse-ranging-technology sensors emit short bursts of high-intensity laser light at up to 250,000…times/sec. The light intensity of a PRT sensor can be up to 1,000× greater than that of a phase-correlation sensor, which uses an emitter that is on continuously.

The light bursts travel to an object or reflector and then reflect back to the sensor’s receiver, or light-sensitive element. The sensor measures the time lapse from the emission of the light burst to the detection of the burst by the sensor’s receiver element. This time is then used to calculate the distance from the sensor to the detected object:
s = c × tl/2
Where s = distance measured in meters
c = speed of light in air (299,792,458 m/sec), and
tl= measured elapsed TOF of the light burst in seconds.

The basic aspect of the present invention comprises of a “diffuse mode” laser sensor used in the present case as a distance measuring device using the target object and having a working voltage of 24V DC supplied by means of a SMPS. The method of measurement is using pulse ranging technology with minimal variations between black-white objects. The device uses a class 1 type laser(safe for human eye) having wavelength of 660 nm with a detection range of 0.2 to 15 meters, containing one transmitter and one receiver incorporated into a single housing. The transmitter light is reflected back to the receiver from a target. The sensor determines the distance to the target and triggers a switching function or supplies the relevant measured value for processing.

The sensor detection range for the present case was set at 7.5 meters ,i.e it would trigger a switching action when an obstruction would appear at approximately 7.5 meters from the boom traversing face of the stacker. The sensor output is connected to a biasing circuit which works to hold the switching trigger of the sensor momentarily, this is then connected to a relay (operating voltage 24 V DC). The relay picks up upon excitation and opens the main contactor relay of the VFD drive for the traverse motor, thus the traverse of the boom is halted and collision with material is avoided.

Furthermore, a visual indication along with a reset switch is provided in the operator cabin so that it shall be possible to attract attention of the operator towards the “sensor triggered tripping action” so that he can reset the system, withdraw the boom to a safer distance, and resume operation safely.

The following advantage can be list out from the present invention
The present invention is intended to provide a system by which collision of moving/traversing structures such as stackers and reclaimers with raw materials can be avoided automatically in a reliable manner, so as to nullify the chances of any collision occurring due to human error or careless operation.

Furthermore it is useful in providing safety of operation to the cabin operator in the stacker machine by avoiding collisions that can cause excessive vibrations or machine derailment.

Another useful aspect of the invention is to protect the movable boom structure against structural damages owing to collisions with the material thereby prolonging its usable life, preventing loss of production hours that occur due to various major or minor instances of collision of stacker booms with raw materials. There by enhancing productivity of the machine and the plant

Industrial Applicability
The present invention used on twin stacker booms to avoid collision of the traversing face of the boom with heaps of raw materials.

Multiple stackers are deployed during the material handling processes. Lack of appropriate protection and warning systems causes them to collide with materials.
The present invention is a kind of 'time-of-flight' technology, where the sensor can be mounted on each side of both booms.

This can reliably analyze the approaching obstruction whether material pile or other structure and trigger a response by breaking the traversing circuit.

The basic construction concept of the present invention is that it uses a sensor and a relay that will cut the control supply to the long traversing operation.

The present invention is designed specifically for stacker applications and is ideal for continuous duty.

The present invention not only useful to safeguard the material handling equipment in the plant but also save the operators.

The present invention calibrated first based on the user’s needs. The reaction time sensor takes for the anti-collision device is a major factor based on its application.

For instance, if the machine moves at 20m/s and the sensor’s reaction time is about 0.5 s, the machine moves about 10m ahead before the Anti-Collision System stops it.

The present invention avoid an accident that arises when two machines/ a machine with an obstruction collide.

Without such a system, the machines operated manually or automatically can move outside the working area and harm the machines, equipment, and structures nearby, causing dangerous situations.

Hence the present invention enhance workplace safetyfor stackers, boost productivity by avoiding breakdowns and augment the optimal monitoring of the operational procedures.
, Claims:
1. An anti-collision system for twin boom stacker machines, the system comprising:
a laser-based distance sensor configured to be mounted on a moving structure, wherein the moving structure is selected from the group consisting of a boom of a crane and a stacker machine; and
an auxiliary relay circuit configured to automatically control a main traverse motor circuit of the stacker machine based on triggers received from the laser-based distance sensor.

2. The anti-collision system for twin boom stacker machines as claimed in claim 1, wherein the laser-based distance sensor is further configured to detect obstructions in the proximity of the stacker machine, including piles of raw material.

3. The anti-collision system for twin boom stacker machines as claimed in claim 1, wherein the laser-based distance sensor is capable of being programmed as per site suited conditions i.e to say that the detection value can be fed into the system based on user specific needs.

4. The anti-collision system for twin boom stacker machines as claimed in claim1, wherein the auxiliary relay circuit is further configured to communicate with the control circuit to break the supply to the main traverse motor of the stacker machine upon receiving triggers from the laser sensor indicating the presence of an obstruction.

5. The anti-collision system for twin boom stacker machines as claimed in claim 1 to 4, further comprising a feedback mechanism to provide feedback to the control circuit regarding the status of the main traverse motor circuit and the position of the stacker boom.

6. The anti-collision system for twin boom stacker machines as claimed in claim 1 to 5, wherein the control circuit is further configured to resume the operation of the main traverse motor circuit after the obstruction is cleared from the proximity of the stacker machine.