CN105446331A - Railway car positioning system and method based on encoder and racks - Google Patents

Abstract

Rail car positioning system and method based on encoder and rack relates to a rail car positioning system and method based on encoder and rack, specifically an encoder and rack positioning system, which controls a non-adjustable speed motor to achieve High-precision positioning method. The invention provides a rail car positioning system and method based on an encoder and a rack with accurate positioning and short positioning control time. The track car positioning system based on the encoder and the rack in the present invention includes a track on which a track car is arranged, and a plurality of racks are arranged on the track along the length direction of the track, and the number of teeth of each rack is different. The bar corresponds to a job target position setting, the rail car is provided with a gear meshing with the rack, the gear central axis is connected to the encoder rotation signal input end arranged on the rail car, and the signal output port of the encoder is connected to the PLC signal input port. The ports are connected.

Description

Rail car positioning system and method based on encoder and rack

technical field

The invention relates to a rail vehicle positioning system and method based on an encoder and a rack, in particular to an encoder and a rack positioning system and a method for controlling a non-adjustable speed motor to achieve high-precision positioning.

Background technique

In some engineering fields, a rail car controlled by electricity needs to locate multiple working positions. How to accurately position the rail car is the prerequisite for the rail car to perform precise operations.

Analyze existing patents:

(1) Invention patent name: automatic positioning device for traveling mechanism of mobile cleaning machine (application number: 201020692747.5)

The invention patent is to install a proximity sensor and a proximity positioning sensor under the frame of the mobile cleaning machine, and set cleaning positioning points on the dam surface where the mobile cleaning machine is installed as needed, and the cleaning positioning points can be 2 or more , set the proximity deceleration sensing block and the proximity positioning sensing block on each decontamination positioning point, the proximity deceleration sensing block is set at a distance of 80-120 mm from the positioning point, the proximity positioning sensing block is set at the positioning point, the approaching deceleration The sensor and proximity positioning sensor are electrically connected with the control circuit in the control cabinet. Use the proximity switch to slow down the brake, use the signal from the proximity switch, the control circuit jogs repeatedly according to the signal from the proximity switch to find the correct position, and the proximity sensor sends out a signal, and locks it through the control circuit.

This patent cannot monitor the position of the rail car in real time.

This patent does not relate to the positioning method of the encoder.

(2) Utility model patent name: a laser ranging positioning system (application number: 201120176926.8)

The laser scanning range finder is arranged on the following mechanism, and the following mechanism is connected with the motor controlled by the processor.

In this solution, the laser needs to be turned off after the trolley is in place for the next action, and the laser distance measurement needs to be turned on when walking. The application of the laser is restricted by the environmental conditions, and it is not suitable for the outdoor environment. This patent does not involve electromechanical control actuators and control positioning methods.

(3) Invention patent name: code positioning device for rail car reciprocating travel and its control mechanism (application number: 200610054590.1)

The rotary coding wheel is installed on the lower end of the frame through the main shaft and is in rolling contact with the track of the rail car. If the rail wheel slips, it will affect the positioning accuracy of the cleaning machine.

This patent does not relate to the method of rack positioning.

(4) Invention patent name: electric drive vehicle linear running positioning system (application number 02111510.9)

The laser position detector is arranged on a fixed object at one end of the center line of the running track of the vehicle, and the control panel receives the signal and controls the driving motor of the vehicle.

The patent does not relate to electromechanical control actuators.

(5) Invention patent name: Linear rail car positioning system and method based on laser ranging (application number 201210493674.0)

When the laser range finder is turned on, the laser beam is emitted to the reflector, and then reflected back to the laser range finder. The data of the laser range finder is input to the control through the data transmission line, and the controller closes the AC contactor by calculating the distance value, thereby The control motor makes the rail car walk through the reduction box.

In this patent, since the reflector is fixed at one end of the track, the laser rangefinder and the reflector need to be on the same straight line and the line must be parallel to the track. The ground collapse will directly cause the laser rangefinder to fail to receive data. Positioning is not accurate.

Through the analysis of the existing positioning technology, it can be seen that each patent has its own application background and its own advantages. In this solution, it is necessary to solve the problem that the operator of the rail car operates on the car, the console is on the rail car, the motor used is an AC geared motor, and the brake power supply is released separately.

Contents of the invention

The present invention aims at the above problems and provides an encoder and rack-based rail car positioning system and method with accurate positioning and short positioning control time.

In order to achieve the above object, the present invention adopts the following technical solutions. The rail car positioning system based on the encoder and the rack in the present invention includes a track on which a rail car is arranged, and a plurality of racks are arranged on the track along the length direction of the track , the number of teeth of each rack is different, one rack is set corresponding to one operation target position, the rail car is provided with a gear that meshes with the rack, and the central axis of the gear is connected to the encoder rotation signal input end arranged on the rail car Connected, the signal output port of the encoder is connected with the PLC signal input port.

As a preferred solution, the PLC of the present invention is arranged on a rail car.

As another preferred solution, the rack in the present invention is arranged on the side of the track, and the gear is arranged on the side of the rail car.

As another preferred solution, the gear in the present invention is connected to the input end of the encoder rotation signal through a coupling.

As another preferred solution, the gear of the present invention adopts a spur gear.

Secondly, the present invention also includes an operation button, a left and right limit sensor, a rail car left travel contactor, a rail car right travel contactor and a display screen, and the PLC signal input port is connected with the operation button signal output port and the left and right limit sensor signal output port respectively. The PLC signal output port is connected with the control signal input port of the rail car left travel contactor, the rail car right travel contactor input port, and the display screen display signal input port respectively; the left and right limit sensors are respectively arranged at the two ends of the track.

In addition, the encoder of the present invention selects an SPC encoder, the PLC adopts Siemens S7-200, and the display screen adopts a Smart700IE display screen; the I0.0 port of the PLC is connected with the signal output port of the encoder, and the I0.1 port of the PLC passes through the rail car The controlled switch of the left travel contactor is connected to the DC-24V power supply, the I0.2 port of the PLC is connected to the DC-24V power supply through the controlled switch of the right travel contactor of the rail car, and the I0.3 port of the PLC is connected to the thermal relay of the rail car travel motor The controlled switch is connected to the DC-24V power supply, the M port of the PLC is connected to the DC +24V power supply, the Q0.0 port of the PLC is connected to the neutral line of the mains through the control terminal of the left travel contactor of the rail car, and the Q0.1 port of the PLC is connected to the mains zero line through The control terminal of the rail car right travel contactor is connected to the mains neutral line, the L port of the PLC is connected to the mains live wire, and the PORT0 port of the PLC is connected to the display signal input port (the rail car left travel contactor and the rail car right travel The contactor is used to control the start and stop of the rail car).

The present invention is based on the track car positioning method of encoder and rack, comprises the following steps:

1) Position detection

Rail car position = grid position + micro position

Grid position: PLC detects different number of pulses generated by racks with different numbers of teeth in different job target positions; there are i job target positions in a project, and when laying racks, i racks with different numbers of teeth determine the job target position , the number of teeth of each rack is pre-tested and stored in the PLC program, the rail car passes through a complete rack, and the PLC controller compares the number of pulses obtained by the encoder on this rack with the number of stored racks to determine Its current grid position; the right row is positive, the current grid position=i±1, the right row is added, and the left row is subtracted;

Micro-position: When the rail car travels near the target position of the operation, the gear touches the rack, and the PLC detects the output pulse of the encoder, and the real-time micro-position = p×X

Among them, X real-time pulse number, p pulse equivalent, the displacement corresponding to the unit pulse is determined by the rack, gear and encoder;

The distance represented by each pulse of p, the gear modulus is M, the number of gear teeth is Z, and the resolution of the encoder is k.

The diameter of the gear pitch circle d=M×Z;

The circumference of the gear pitch circle C=π×d=π×M×Z;

p = circumference of gear pitch circle/resolution of encoder = π×M×Z/k;

The rail car walks between the two racks, and the PLC obtains the position through the travel time and average speed.

in, Indicates the average speed of the rail car, and t represents the time for the rail car to travel;

The rail car is moving to the right, the relationship between the number of pulses obtained by the PLC controller and the track position of the car

The rail car is at the position with rack = pX;

The position of the railcar at no rack=v(t)×t;

(i is the position with rack, j is the position without rack);

The micro position is determined by the rack and has nothing to do with the position without rack, so can be made by replace.

2) positioning

The positioning of the rail car of the present invention is in the micro-position interval. After the position detection, the closed-loop feedback loop mode is used for positioning. Fig. 5 is a block diagram of the closed-loop feedback positioning of the rail car of the present invention;

In the PLC controller, the operation target position relative pulse y _i is compared with the actual parking relative pulse position x _i , if x _i >y _i , the rail car needs to continue to walk in the reverse direction automatically, if x _i <y _i then the track The car needs to move in the positive direction, when

|x _i -y _i |<Δ

Among them, Δ is the positioning error, which finally reaches the determination of the micro position.

As another preferred solution, the gear of the present invention consists of two master and slave gears:

The gear modulus is M=3mm;

The number of teeth of the main gear Z ₁ =40;

The diameter of the gear pitch circle d=M×Z ₁ =3×40=120mm;

Circumference C ₁ of the main gear pitch circle = π × d = 376.8mm;

Number of teeth of the slave gear Z ₂ =20;

Transmission ratio i ₁₂ of master and slave gears = Z ₁ /Z ₂ =40/20=2;

The circumference of the comprehensive gear index circle of the master-slave gear structure C=C ₁ /i ₁₂ =120/2=60mm;

The pitch of the rack t=πM=3π;

Encoder is SPC encoder, resolution k=1024;

The pulse equivalent of the micro position p = the circumference C of the comprehensive gear index circle of the master-slave structure / the resolution k of the encoder,

p=60/1024 (mm/pulse);

A rack with 56 teeth is laid at work target position 1, a rack with 58 teeth is laid at work target position 2, a rack with 60 teeth is laid at work target position 3, and a rack with 62 teeth is laid at work target position 4;

The PLC controller of the system adopts Siemens S7-200, and port0 is connected to the Siemens man-machine interface Smart700IE display;

After the track laying is completed, first pre-read the pulse number of each track and write it into the PLC calibration grid position;

The initial position of the rail car is at the far left, and the rail car is sensed by the left limit proximity sensor. The rail car starts to walk from the left, and the grid position is 1. When the rail car reaches point A, that is, the gear is in contact with the rack and installed on the rail car The PLC controller starts to calculate the displacement. The rail car is within the range of AA, that is, the rail car runs for 5s before the gear meshes with the No. 1 rack. The average speed of the rail car is 1m/s. When the rail car reaches point A, the track The car travels 1×5=5m;

The gear starts to mesh with the No. 1 rack, the encoder starts counting, the PLC controller calculates the real-time micro-position s, and the number of pulses generated by the encoder X ₁ =1000, then the real-time micro-displacement is

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1000</span>}\frac{\mathrm{<span\; class="notranslate">\; 60</span>}}{\mathrm{<span\; class="notranslate">\; 1024</span>}}<span\; class="notranslate">\; \&cong;</span>\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; mm</span>}<span\; class="notranslate">\; ;</span>$

When the gear of the rail car leaves the No. 1 rack, the pulse fed back by the No. 1 rack through the encoder is recorded in the PLC controller.

56*t/p=56*3*π*1024/60=9003;

Real-time absolute displacement of rail cars

9003*p=56*t=56*3*π=527.52mm;

The rail car runs within the range of BB, that is, the grid position is 2, and the rail car runs for 4 seconds before the gear meshes with the No. 2 rack, then 1×4=4m;

After that, the gear starts to mesh with the No. 2 rack, the encoder starts to count, and the PLC calculates the micro position.

The number of pulses generated by the encoder at this time is X ₂ =1500, then the real-time micro-displacement is

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1500</span>}\frac{\mathrm{<span\; class="notranslate">\; 60</span>}}{\mathrm{<span\; class="notranslate">\; 1024</span>}}<span\; class="notranslate">\; \&cong;</span>\mathrm{<span\; class="notranslate">\; 87.9</span>}\mathrm{<span\; class="notranslate">\; mm</span>}<span\; class="notranslate">\; .</span>$

Beneficial effect of the present invention

The rack of the invention does not cover the entire track, which reduces the engineering cost.

In the present invention, racks with different numbers of teeth are laid on the guide rails at different target positions. The encoder of the rail car reads the pulses generated by the racks. Different racks generate different pulses. The PLC does not need to memorize the absolute position of the rail car. The target position of the operation, the PLC will obtain the position of the rail car grid.

The invention only locates the operation target attachment (micro-position) that requires accurate positioning, and reduces the control time required for positioning.

The rack of the present invention is laid intermittently, and the positioning of the operation target attachment (micro-position) for precise positioning is completed in a continuous guide rail. In this method, there is no accumulative positioning error introduced by the continuous laying of the rack and the seam of the rack .

The invention controls the three-phase asynchronous braking motor through the existing conditions to achieve the automatic positioning of the rail car.

The invention adopts the pulse fed back by the gear rack and the gear meshing to position the rail car, and the pulse is generated by an encoder with high precision and small error.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the following expressions.

Fig. 1 is a block diagram of the rail car positioning system of the present invention.

Fig. 2 is a schematic diagram of the relative positions of the gear and the rack in the present invention.

Fig. 3 is a schematic diagram of laying guide rails of the present invention.

Fig. 4 is a graph showing the relationship between the number of pulses obtained by the PLC controller of the present invention and the track position of the car.

Fig. 5 is a block diagram of closed-loop feedback positioning of a rail car in the present invention.

Fig. 6 is a schematic diagram of the structure of the master and slave gears of the present invention.

Fig. 7 is a schematic block diagram of the circuit of the present invention.

Fig. 8 is a control circuit diagram of the present invention.

Fig. 9 is a main circuit diagram of the present invention.

Among Figures 2 and 6, 1 is a rack, 2 is a track, 3 is a wheel, 4 is a gear, 5 is an encoder, 6 is a rail car, 7 is a driving wheel, and 8 is a driven wheel.

detailed description

As shown in the figure, the present invention is based on the rail car positioning system of the rack and the encoder. The positioning system is installed on the rail car and moves with the rail car; Vehicles, encoders, PLC controllers, and motors installed on rail cars; racks are determined according to the number of work target positions, and each work target position is inlaid with a rack with a different number of teeth, and the length of the rack is determined by the inertia of the rail car and The adjustment range of the fine-tuning positioning depends on the adjustment range; the positioning system is installed on the side of the rail car, and the positioning system is equipped with gears, and the rack is installed on either side of the rail car's walking rail. The movement of the car rotates, and the rotation of the gear drives the encoder to rotate through the coupling to generate a pulse signal. The pulse signal is transmitted to the PLC controller. Through this pulse signal and the average speed of the rail car, the program calculation in the PLC controls the track. The car is accurately positioned.

The gear adopts a cylindrical gear; the rack matches the selected gear. In order to reduce the engineering cost, the patented method does not affect the positioning operation. The rack is laid intermittently on the track and only laid near the target position of the operation.

Lay a rack that matches the tooth pitch of the gear at the work target position on the guide rail. The length of the rack must first be greater than the uncertain displacement length of the rail car when it stops, so as to ensure that the rail car is within the range of the rack when it is positioned at the micro position. , and secondly, the number of teeth for laying the rack at each job target position should also be different, as shown in Figure 3.

rack and pinion positioning mechanism

The meshing of the gear and the rack converts the linear motion of the rail car into a circular motion. The encoder is connected to the gear through a coupling, and the output pulse of the encoder reflects the displacement of the rail car.

The operation requires that the rail car must accurately locate the target position of the job, but due to the system quality of the entire rail car, there is inertia from moving to stop; the mechanical structure of the rail car changes randomly; the system requires precise position detection design.

Location detection method:

The positioning method and the position detection method of the present invention are realized through grid position positioning and micro position positioning detection methods.

Rail car position = grid position + micro position

Grid position: It is the number of different pulses generated by the racks with different numbers of teeth detected by the PLC for different job target positions.

Assuming that there are i job target positions in a project, i racks with different numbers of teeth are required to determine the job target position when laying racks. The number of teeth of each rack is the initial stage of the entire system construction, and the pre-test has been stored in the PLC program. Yes, the rail car passes through a complete rack, and the PLC controller compares the number of pulses obtained by the encoder on this rack with the number of stored racks to determine its current grid position, so that the PLC does not need to configure non-volatile data storage. At the same time, the left and right rows should also be considered. For example, assuming that the right row is positive, the current

Grid position=i±1 (adding to the right line, subtracting from the left line);

Micro-position: It is realized when the rail car travels to the vicinity of the target position, the gear touches the rack, and the PLC detects the output pulse of the encoder. Real-time micro position = X × p;

Among them, X real-time pulse number, p pulse equivalent (mm/pulse), the displacement mm corresponding to the unit pulse is determined by the rack, gear and encoder,

The distance represented by each pulse of p (mm/pulse), the gear modulus is M, the number of gear teeth is Z, and the resolution of the encoder is k (pulse/revolution), then

The diameter of the gear pitch circle d=M×Z;

The circumference of the gear pitch circle C=π×d=π×M×Z;

p = circumference of gear indexing circle/resolution of encoder = π×M×Z/k (mm/pulse);

When the rail car is walking between the two racks, the PLC obtains the position through the travel time and average speed

in, The average speed at which the rail car travels, t is the time at which the rail car travels.

Assuming that the rail car is moving to the right, the relationship between the number of pulses obtained by the PLC controller and the track position of the car is shown in Figure 4.

With the grid position and micro position, PLC realizes the detection of the job target position.

The rail car is at the position with rack = pX;

The position of the railcar at no rack=v(t)×t;

(i is the position with rack, j is the position without rack);

Since in this patent, the micro position is determined by the rack, which has nothing to do with the position without rack, so can be made by replace.

The grid position is not introduced, and the number of pulses obtained by the PLC controller is continuously accumulated to realize the position detection of the track. The PLC implementation can also detect the target position of the work, but the counting error of the gear, rack and encoder at the end of each target position will be detected. Accumulation, the introduction of the grid position, is equivalent to the counting error before the current position is cleared, which minimizes the counting error.

Positioning method:

The positioning of the rail car is in the micro-position interval, and the present invention adopts a closed-loop feedback loop mode for positioning.

In the PLC controller, the operation target position relative pulse y _i is compared with the actual parking relative pulse position x _i , if x _i >y _i , the rail car needs to continue to walk in the reverse direction automatically, if x _i <y _i then the track The car needs to move in the positive direction, when

|x _i -y _i |<Δ

Among them, Δ is the positioning error, which finally achieves the determination of the micro position and realizes accurate positioning.

Example:

Rack and pinion positioning mechanism: the gear consists of two master and slave gears:

As shown in FIG. 6 , the number of teeth of the gear is less than the number of teeth of the actual gear for clarity of illustration. With such a structure, the gear ratio is increased, which can improve the detection resolution of the micro position.

In this example:

The gear modulus is M=3mm;

The number of teeth of the main gear Z ₁ =40;

The diameter of the gear pitch circle d=M×Z ₁ =3×40=120mm;

Circumference C ₁ of the main gear pitch circle = π × d = 376.8mm;

Number of teeth of the slave gear Z ₂ =20;

Transmission ratio i ₁₂ of master and slave gears = Z ₁ /Z ₂ =40/20=2;

The circumference of the comprehensive gear index circle of the master-slave gear structure C=C ₁ /i ₁₂ =120/2=60mm;

The pitch of the rack t=πM=3π;

Encoder is SPC encoder (incremental pulse encoder), resolution (pulse/rotation) k=1024

The pulse equivalent of the micro position (mm/pulse) p = the circumference of the comprehensive gear index circle of the master-slave structure / the resolution k of the C encoder,

p=60/1024 (mm/pulse);

In this embodiment, a rack with 56 teeth is laid at the working target position 1, a rack with 58 teeth is laid at the working target position 2, a rack with 60 teeth is laid at the working target position 3, and a rack with 62 teeth is laid at the working target position 4 rack, as shown in Figure 3.

The PLC controller of the system adopts Siemens S7-200, and port0 is connected to the Smart700IE display screen of Siemens man-machine interface to display displacement in real time. The system block diagram, control circuit diagram, and main circuit diagram are shown in Figures 8 and 9:

QM: travel motor circuit breaker

KM1: rail car left travel contactor

KM2: Rail car right travel contactor

RT: thermal relay for rail car traveling motor

M: walking motor DC+: DC +24V power supply

DC-: DC-24V power supply

I0.1: Rail car status input terminal

I0.2: Rail car status input terminal

I0.3 Rail car state input terminal

I0.0: encoder pulse input terminal

M: PLC power input common terminal

Q0.0: PLC output terminal

Q0.1: PLC status output terminal

L: PLC input power

N: PLC input power

PE: power ground

PORT0: RS485 port

PORT1: RS485 port

DCS: Distributed Control System

After the track laying is completed, the pulse number of each track is pre-read first. These data are invariable and written into the program to calibrate the grid position.

The initial position of the rail car is defined at the far left end. The rail car is sensed by the left limit proximity sensor. The rail car starts to walk from the left side of the above figure, and the grid position is 1. When the rail car reaches point A (the gear is in contact with the rack), install it on The PLC controller on the rail car starts to calculate the displacement. The rail car runs for 5 seconds within the range of AA and before the gear meshes with the No. 1 rack. The average speed of the rail car is about 1m/S. Then, when the rail car reaches A, the rail car has traveled about

1×5=5m

The gear starts to mesh with the No. 1 rack, the encoder starts counting, and the PLC controller calculates the real-time micro-position s. Assuming that the number of pulses generated by the encoder X ₁ =1000, the real-time micro-displacement is

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1000</span>}\frac{\mathrm{<span\; class="notranslate">\; 60</span>}}{\mathrm{<span\; class="notranslate">\; 1024</span>}}<span\; class="notranslate">\; \&cong;</span>\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; mm</span>}<span\; class="notranslate">\; ;</span>$

When the gear of the rail car leaves the No. 1 rack, the pulse fed back by the No. 1 rack through the encoder is recorded in the PLC controller.

56*t/p＝56*3*π*1024/60＝9003 (pulse)

Real-time absolute displacement of rail cars

9003*p＝56*t＝56*3*π＝527.52mm

The rail car runs within the range of BB, the grid position is 2, and the rail car runs for 4 seconds before the gear meshes with the No. 2 rack, then 1×4=4m;

After that, the gear starts to mesh with the No. 2 rack, the encoder starts to count, and the PLC calculates the micro position.

Assuming that the number of pulses generated by the encoder at this time is X ₂ =1500, the real-time micro-displacement is

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1500</span>}\frac{\mathrm{<span\; class="notranslate">\; 60</span>}}{\mathrm{<span\; class="notranslate">\; 1024</span>}}<span\; class="notranslate">\; \&cong;</span>\mathrm{<span\; class="notranslate">\; 87.9</span>}\mathrm{<span\; class="notranslate">\; mm</span>}<span\; class="notranslate">\; ;</span>$

It can be understood that the above specific descriptions of the present invention are only used to illustrate the present invention and are not limited to the technical solutions described in the embodiments of the present invention. Those of ordinary skill in the art should understand that the present invention can still be modified or Equivalent replacements to achieve the same technical effect; as long as they meet the needs of use, they are all within the protection scope of the present invention.

Claims (8)

1. The rail car positioning system based on the encoder and the racks comprises a rail, wherein a rail car is arranged on the rail, and the rail car positioning system is characterized in that a plurality of racks are arranged on the rail along the length direction of the rail, the number of teeth of each rack is different, one rack is arranged corresponding to one operation target position, a gear meshed with the rack is arranged on the rail car, the central shaft of the gear is connected with the rotating signal input end of the encoder arranged on the rail car, and the signal output port of the encoder is connected with the signal input port of the PLC.

2. The encoder and rack based railcar positioning system of claim 1, wherein said PLC is disposed on a railcar.

3. The encoder and rack based rail car positioning system of claim 1, wherein the racks of different numbers of teeth are disposed on the sides of the track and the gears are disposed on the sides of the rail car.

4. The encoder and rack based railcar positioning system of claim 1, wherein said gear is coupled to an encoder rotational signal input through a coupling.

5. The encoder and rack based railcar positioning system of claim 1, wherein said gears are cylindrical gears.

6. The railcar positioning system based on the encoder and the rack according to claim 1, further comprising an operation button, a left and right limit sensor, a railcar left running contactor, a railcar right running contactor, and a display screen, wherein the PLC signal input port is connected to the operation button signal output port, the left and right limit sensor signal output ports, respectively, and the PLC signal output port is connected to the railcar left running contactor control signal input port, the railcar right running contactor input port, and the display screen display signal input port, respectively; the left limit sensor and the right limit sensor are respectively arranged at two ends of the track.

7. The encoder and rack based railcar positioning system of claim 6, wherein said encoder is an SPC encoder, PLC is Siemens S7-200, display screen is Smart700 IE; an I0.0 PORT of the PLC is connected with an encoder signal output PORT, an I0.1 PORT of the PLC is connected with a direct current-24V power supply through a controlled switch of a rail car left walking contactor, an I0.2 PORT of the PLC is connected with the direct current-24V power supply through a controlled switch of a rail car right walking contactor, an I0.3 PORT of the PLC is connected with the direct current-24V power supply through a controlled switch of a rail car walking motor thermorelay, an M PORT of the PLC is connected with a direct current +24V power supply, a Q0.0 PORT of the PLC is connected with a commercial power zero line through a control end of the rail car left walking contactor, a Q0.1 PORT of the PLC is connected with the commercial power zero line through a control end of the rail car right walking contactor, an L PORT of the PLC is connected with a commercial power live wire, and a PORT0 PORT of the PLC is connected with a display signal input PORT.

8. A rail car positioning method based on an encoder and a rack is characterized in that:

1) position detection

Railcar position-grid position + micro position

Grid position: detecting different pulse numbers generated by racks with different tooth numbers at different operation target positions by the PLC; the method comprises the following steps that i operation target positions exist in one project, when racks are laid, the operation target positions are determined by the i racks with different tooth numbers, the tooth number of each rack is tested in advance and stored in a program of a PLC, a rail car passes through one complete rack, and a PLC controller compares the number of pulses obtained by an encoder on the rack with the number of the stored racks to determine the current grid position of the PLC controller; the right row is positive, the current grid position is i +/-1, the right row is increased, and the left row is decreased;

micro-position: when the rail car runs to the position near the operation target position, the gear is in contact with the rack, the PLC detects the output pulse of the encoder, and the real-time micro position is p multiplied by X;

the real-time pulse number of X, the equivalent of p pulse, and the displacement corresponding to the unit pulse are determined by a rack, a gear and an encoder;

p (mm/pulse) represents the distance of each pulse, M represents the gear module, Z represents the gear tooth number, and k (pulse/revolution) represents the resolution of the encoder, then

The diameter d of the gear reference circle is M multiplied by Z;

the circumference C of the gear reference circle is pi multiplied by d pi multiplied by M multiplied by Z;

p is the circumference of the gear reference circle/resolution of the encoder pi x M x Z/k;

the rail car travels between the two racks, the PLC obtains the position through the traveling time and the average speed,

wherein,the average speed of the rail car, t the time of the rail car;

the track car moves right, the relationship between the pulse number obtained by the PLC controller and the track position of the car walking

The rail car is located at a position with a rack (pX);

the position of the rail car without the rack is v (t) x t;

(i is the position with the rack, j is the position without the rack);

since in this patent the micro-position is determined by the rack, independent of the non-rack position, the micro-position is determined by the rackCan be prepared fromInstead.

2) Positioning

The positioning of the rail car is carried out in a micro-position interval by adopting a closed-loop feedback loop mode after the position detection;

operating target position is set to pulse y in PLC controller_iPulse position x relative to actual parking_iBy comparison, if x_i>y_iIf x is greater than x, the rail car will need to continue to move in the reverse direction automatically_i<y_iThe rail car needs to walk in the positive direction when

|x_i-y_i|<Δ

Wherein, delta is the positioning error, and finally the micro-position is determined.