[abstract] this article proposed realizes using FPGA and the encoder based on the SOPC industry crane lift hook’s position survey. This design through has realized regarding related encoder output signal’s gathering processing regarding the lift hook vertical range survey, and regarding has carried on the discussion in the application practice’s question.
[key word] SOPC; FPGA; Position survey
1. Introduction
In major industry crane movement, because the crane driver position often leaves the ground to be very high (generally is 20 meters to 50 meters), the driver is very difficult judges lift hook’s accurate position accurately, can only depend upon ground men’s direction completely, such efficiency is low, moreover the production safety is responsible by the ground control personnel, to have accident’s probability completely to be high. For can cause the crane driver to know that lift hook’s real-time accurate position, raises the productivity, cuts accident’s formation rate, this article proposed one kind based on SOPC (system on a programmable on the chip piece system) the leveling method. The SOPC technology is integrates the overall system on the sole semiconductor chip, integrates the digit on the sole chip, signal gathering and processing, the I/O connection, the memory, MCU (microprocessor) and DSP (digital signal processor) and so on chips. Uses the SOPC technology to be possible to reduce the peripheral circuit chip, reduces the complete machine cost, enhances the design the reliability.
This article designs uses Atlera Corporation’s FPGA:CycloneII 1P2C8[1] to take the systems control the core to realize SOPC. Its nimble scene alterability, may dispose ability again, is convenient to system’s each kind of improvement, in does not change in hardware circuit’s foundation also to be possible to further enhance system’s performance. This design has high speed, precise, reliable, the anti-jamming to be strong and scene programmable and so on merits.
2. survey principle
The industry transfer gantry by the lift hook, the movable pulley group, the drum is composed generally, the electrical machinery through the speed reducer head roll, drives the lift hook to reciprocate in the vertical plane. Like this through surveys to drum’s revolving displacement transforms obtains lift hook’s vertical displacement. Through may realize in the drum axle center installment revolving encoder to its displacement’s survey.
(1)
And S lift hook to place vertical range;
The N lift hook has the pulse number which the S displacement internal rotation encoder records;
N1 movable pulley number of classes;
N2 revolving encoder’s P/R;
The L lift hook’s higher authority limits to the bottom surface distance;
D drum diameter.
According to the formula (1) may know, when the revolving encoder has decided that crane’s movable pulley number of classes has decided that the drum diameter and lift hook’s higher authority limits to the bottom surface distance may survey obtains, the lift hook only occurs to the ground vertical range in the lift hook in the ground vertical displacement internal rotation encoder record results in the pulse number to concern.
3. overall design thought
(1) may know by the formula, surveyed regarding lift hook’s vertical displacement through this formula transforms to has installed in the drum coaxial increase revolving encoder output pulse counting. Through regarding crane movable pulley number of classes N1, revolving encoder’s P/R N2, lift hook’s higher authority limits again to bottom surface distance L and the drum diameter D these four parameter establishment, obtains the lift hook after the computation regarding the horizon vertical range.
4 system structures and function
Figure one
4.1 encoder signal input and electro-optical isolation module
The encoder signal input module is responsible for the increase type revolving encoder’s signal input, the electro-optical isolation module is responsible for the encoder signal and the system board electricity isolation. The increase rotary system encoder selects the ohm dragon E6B2 collecting electrode opening output. Because the drum diameter is quite big (is bigger than 1m generally), and the rotational speed is quite slow, the encoder output frequency is quite low (<10k/s), the electro-optical coupler selects the TLP series. This module receives encoder’s A, B two signals, limits the signal with the crane higher authority (higher authority to limit signal is passive often opens node). When the crane lift hook moves to the higher authority time limit, the higher authority limits the signal closed, and the FPGA received signal limits the higher authority to bottom surface distance L loads into the counter starting value.
4.2 EMI and power source modules
Because this design applies in the industry scene, to solve the scene power source disturbance problem, this design has used X electric capacity, the Y electric capacity and the syntype inductance carries on the filter for the power source, obtains 24v, 3.3v, 1.5v through the transformer and the constant voltage module to provide the encoder supply voltage separately, the CycloneII 1P2C8 IO mouth supply voltage and the core supply voltage.
4.3 FPGA control module
FPGA uses Altera CycloneII 1P2C8, this component has 8256 LE units, 36 M4K modules, can satisfy this design requirements. The FPGA module uses design method [2] from the top, first produces each design social stratum (this design is from the top two structures), the task of design will decompose into the different functional element, each part has the definition input to output and to carry out the special logical function specially. Then, produces one top layer module which forms by the various functional element interconnection. Ultimate design each part. This design top layer module describes with the graph, direct-viewing, clear, extendibility, the first floor part describes with VHDL[3].
FPGA decomposes according to the function into the following six function block: Filter module (filter), encoder phase recognition module (phasecheck), loading module (MCload), computation module (Calplus), bidirectional counting module (Count16bit), demonstration actuation module (LEDControl). The FPGA top layer graph description sees Figure one.
Under system receive electro-optic coded disk’s signal A, B through the filter module filtration peak, the concave peak equisignal disturbance, (i.e. crane lift hook uppers shift through the coding mask phase recognition module recognition crane drum clockwise reverse condition moves to condition), and is reversing the condition the signal to send in the bidirectional counter registry pulse integer. The loading module N1, N2, L and the D four parameter loading, and calculates obtains each pulse to correspond lift hook’s displacement distance. The computation module receive real-time pulse number, each pulse correspondence’s lift hook displacement is away from and lift hook’s higher authority limits to the bottom surface distance calculates the lift hook real-time to be opposite in the ground distance, again through display module decoding and direct drive LED demonstration lift hook real-time altitude. The following is the filter module VHDL description
Figure one
library IEEE;
use IEEE.Std_logic_1164.all;
use IEEE.std_logic_signed.all;
use IEEE.std_logic_arith.all;
entity fitter is port (clk, A:in std_logic; AOUT:out std_logic); end entity filter;
architecture Crane of filter is
signal data0, data1, data2, data3, data4, data5:integer range 0 to 1;
signal dataall:integer range 0 to 7;
begin
process(clk)
begin
if clk’event and clk=’1′ then
if A=’1′ then data0<=1; else data0<=0; end if;
data1<=data0; data2<=data1; data3<=data2; data4<=data3; data5<=data4;
dataall<=data0 data1 data2 data3 data4 data5;
if (dataall>=3) then AOUT<=’1′; else AOUT<=’0′; end if;
end if;
end process;
end architecture Crane;
5. application example
This designs applies successfully two makes steel in 56 ton transfer gantries in Wuhan Steel Corporation. On this crane the limit to ground range 18m, drum diameter 1000mm, the lift hook pulley number of classes is 5, installs in the drum axle center increase type revolving encoder for the ohm dragon e6b2-cwz6c drain electrode output type, the resolution is 360P/R. After calculates each pulse correspondence lift hook high and low distance is 1.74mm, the loading counter starting value is 10345.
The debugging initial period discovery lift hook demonstration displacement must be bigger than the theoretical value, but under laboratory condition normal, therefore the suspicion encoder pulse output receives the disturbance in the scene. Has traded the shielded wire after the scene this phenomenon still exists, with portable oscilloscope observation discovery, encoder signal after experience certain length transmission the signal has had the distortion, among each pulse’s high level has the 48us concave peak, enters when FPGA after the light pair caused has counted by mistake, we have designed windowing filter (filter) in view of this concave peak, underwent the actual debugging to eliminate the scene disturbance question, Figure two is from the scene gathering profile, Figure three adds the profile which the filter gathered.
Figure two
Figure three
6 concluding remark
This article proposed applies FPGA and the revolving encoder’s SOPC design survey industry large-scale crane lift hook position. This design has the measuring accuracy to be high, the cost is low, the movement is reliable, maintenance quantity few characteristics. Should design applies successfully in the Wuhan Steel Corporation two steel-making, after its crane primary mission is makes steel completes the hot metal ladle from the ground the approximately nine meters control desks hangs to the ground cooling space cools, because the hot metal ladle volume is big, generally the driver collides the hook depending on the feeling the lift hook place to be able to locate, because the lift hook weight is very heavy (about 1 ton) this kind of collision to be very big regarding the load bearing hot metal ladle cardan shaft harm, after applying this design the crane driver can very accurate know that lift hook’s position did not need depending on the collision to locate, lengthened cardan shaft’s life, raised a localization success ratio, reduced the productive time, enhancedProduction efficiency.
Reference:
[1] Cyclone II Device Handbook. www.altera.com
[2] skahiuk. programmable logical system’s VHDL design technique. Nanjing: Southeast University publishing house, 1998
the [3] forest is sensitive, Fang Yingli. The VHDL number system design and the top level are comprehensive “M]. Beijing: Electronics industry publishing house, 2002.
