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There has been great increase in interest in impact source determination. Source determination is one of the major problems in the fields like army and other part of industry. The idea Impact source determination is to identify the source from which the impact has been given. By knowing the source and appropriate action can be taken in the real time. This will help in the researches to know about the circumstances of any impact by any particular source. It will also help in testing the material before it can be sent to the market. There are various algorisms by which the Impact source determination can be done. In this paper we suggest a fuzzy logic approach for the determination of source of impact. This paper also suggests a procedure is development of chip for this purpose. It is hoped that such an impact source determination chip will be useful in the handy devices.
Data acquisition, Fuzzy Logic, Verilog, Cadence, Encounter, Ambit Build Gates, Virtuoso
There is significant works done in impact source determination. Reviews of existing lecture in impact source determination are given below:
1) Non destructive techniques for impact source identification and crack detection in ceramic plates by Shashank Kamthan. In this paper shashank has use time domain and frequency to determine the impact and source of impact. They are using two sensors and comparing the signal from both the sensors.
2) Impact source identification in finite isotropic plates using a time-reversal method: theoretical study by Chunlin Chen and Fuh-Gwo Yuan. In this study Chunlin and Fuh used time reversal concept with the help of array of sensors. The impact location and impact loading time history is reconstructed using the time reversal concept.
Fig1: Hardware setup of Impact source Determination system
The DEWETRON DEWE 43V data actuation system is an instrument which captures the data from the different sources (sensors). The experiment was done using analog sensor so channel1 was used. The other main part which is used is DEWSOFT software. The Dewetron Dewe 43V is connected to the computer using USB 2.0 interface. Dewesoft is the software which captures the data from Dewetron Dewe 43V through USB and saves data in hard drive of computer. The Dewesoft software also converts the data from Dewetron Dewe 43V in graphical data for the better visualization. In Fig: 1 shows plate with a sensor on it, sensor is connected with Dewe 43 V and Dewe 43 V is further connected with computer with USB 2.0.
In the experiment the plate is divided in 16 different sections as show in fig: 2
Fig 2: Plate is divided in 16 sections
When the plate is hit by other source the wave is form in the plate that generated wave is recorded by the sensor. The behavior of the wave depends on many factors like position of the impact from the sensor, force of the impact and material used to hit the impact. The generated wave (data) is saved in the computer for the future calculations. The saved data will not give the sufficient information to make out which material was used but this data can be calibrated to get the material information. From the data Rms Value, Sum of the values, and time of peak can be calculated. This information can be used in fuzzy logic rules to find out the material.
In the experiment the hammer was used as the impact source on the plate and material of the hammer was Steel and Rubber.
> The sensor was set on the plate and connected to data acquisition system which is further connected to computer.
> The surface of the plate is hit by the source (Here material were Steel and Rubber).
> Sensor sends the generated acoustic wave to data acquisition system (Dewetron Dewe 43 V)
> Software Dewesoft saves the data from Dewetron Dewe 43 V.
> Calculation is done to calculate the Rms, Sum of Value and Relative time of peak.
> Different rules were defined (Two techniques were used First Dewesoft offline mathematics and second Fuzzy logic).
The flow chat in fig: 3 show procedure
Fig 3: Flow chart for the Procedure
Fuzzy Logic Approach
Fuzzy logic is very popular these days. In today>s world it is used in many applications in engineering. Fuzzy logic was developed by Lotfi A. Zadeh. In this paper fuzzy logic is used to set the rule which defined the material according to their properties like RMS Value, Sum of the value and time of peak. The Matlab program was written to start the data acquisition software, setup the properties, capture the data, and import the data from data acquisition software to matlab. The imported data is calibrated and RMS, Sum and Time of Peak. These three parameters are used in Fuzzy logic.
The Various parameter used are shown in table1
Output in the fuzzy logic is between 0 and 1. 0 to 0.5 is defined for the Rubber and 0.5 to 1 is defied for the Steel.
Low Med High
RMS 0 > 0.4 0.4 > 0.65 0.65 > 1
Sum 0 > 150 150 - 260 260 > 700
PTime 0 > 110 110 - 750 750 > 1500
Table 1: Various parameter and range
Input and Output used in fuzzy logic
Input Member functions used in fuzzy logic are RMS, Sum, Tpeak and the output Member function used is material. The fig 3 shows the input and output member function in fuzzy logic
Fig 3: Input and Output Member Functions
Fig 4 shows the rule editor window. In the rule editor window the rule are define to find which material used. Fig 5 shows the rule viewer Window.
Fig 4: Rule Editor Window
Fig 5: Rule Viewer Window
In Fig 6 and Fig 7 show the waveform for rubber impact and Steel impact respectively.
Fig 6: Wave form produce by impact of Rubber
Fig 7: Wave form produce by impact of Steel
Different rule can be made using Fig 3 and Fig 4. Rms for rubber is 0.223, sum of values for 189 and peak time was 74. Rms for steel is 0.327, sum of values for 300 and peak time was 200
The rules used to define this are as follows:
Rule for rubber
If (Rms is low) and (sum is Med) and (tpeak is low) then (material is rubber) > (1)
Rule for steel
If (Rms is low) and (sum is high) and (tpeak is Med) then (material is steel) > (2)
In rule in equation 1 is the rule for the rubber and the rule in equation 2 is rule for steel. The Rms value is used to find the force use for the impact. If the force is less than the Rms value is low. As the force value increases the Rms value increases. Sum of the values and peak time are used to find the material used because when sum of value is on the lower side and peak time is also on the lower side then the material used is Rubber and on the other side when sum and peak time both are on the higher side then the material used is steel.
Development of Chip
Here we suggest a procedure for development of Impact source determination. For the chip development cadence tools in UNIX environment are used. Some of the tools are Ambit build gate, Encounter, Virtuoso. Ambit build gate tool is used to convert the Verilog code in to netlist which can be read by encounter. The encounter tool uses the netlist and make layout. The layout from the encounter is exported to virtuoso who adds pads to the layout and do the padding and routing to make a final chip that can be send to Mosis or other companies for the chip fabrication.
The general information used in designing and writing the code in Verilog.
> Binary code used for the input and outputs are show in the Table 2
Name Level Direction Binary code used
Low Low Input >00>
Medium Med Input >01>
High High Input >11>
Material Rubber Output >1>
Material Steel Output >0>
Table 2: Binary Code user in the Verilog code and for making the logic equation
> Comparator circuit was used for if else condition. Comparator AND Gate and NOT (Inverter) Gates were used.
> Truth table was made using that truth table Verilog code and behavioral model was made.
> Padding is done using Virtuoso layout.
Ambit Build Gates
To create a chip of Impact source determination we have to write a Verilog code. That Verilog code should be converted in netlist so that it can be understand by encounter. The procedure and commands used in Ambit build gate to create a netlist are as follows:
> Directory is created for the project.
> read_tlf ami06 (read the library)
> set_global hdl_vhdl_environment synopsys (control the different library used for the project)
> read_verilog code_name.v (read the Verilog code with name code_name.v)
> do_build_generic (this will do the synthesis)
> do_optimiz (this will map the synthesized logic to ami06 std cells)
> write_verilog netlist.v (write a netlist netlist.v)
After the netlist is created this netlist.v file should be used in encounter to create a layout. The procedure of encounter is as follows:
> Invoke encounter
> Import design in encounter using Import design command.
> Set the Floorplan which depend on the project
> Add rings will add the power ring in layout that is Power ring (vdd) and ground ring (gnd). To add rings the different metal layer are used. For top and bottom ring metal 3 layer is used and for left and right metal ring metal 2 layers is used.
> Route the ring to add power and ground lines for the layout.
> Place Jtag and Place standard cell to place attach components.
> Do the nanorouting which will route the components and power ring.
> After nano routing the layout in encounter is complete and it will look like as shown in fig 8.
> The next step is to verify the connectivity. This makes sure that the layout is connected and if there are error follow the error message to make changes in routing.
> To export the design in virtuoso for padding encounter layout should be saved in two formats. First is *.def and second is *.gds. These two files are used in virtuoso to import the layout design.
Fig 8: Final layout in encounter
Layout is the representation of IC (integrated circuits) in the forms of shapes of metal layers and various components used. This layout should be connected to the pins of the chip which is called pads and the process is called padding. The padding can be done in virtuoso tool of cadence. The procedure to do padding in virtuoso is as follows:
> Invoke Virtuoso
> Create a library. This library will be used throughout the project.
> Import *.gds file from the directory where it was saved into the library created.
> Import *.def file. This will import the whole of layout from encounter to virtuoso library.
> Now for padding layout should be used in the form of symbol. For that new symbol in same cell of layout should be made. Symbol is shown in fig 9.
> Create new cell for the padding schematic and layout.
> In the new cell create a padding schematic using symbol created in previous steps.
> The padding schematic is shown in fig 10.
Fig 9: Symbol of ISD
Fig 10: Schematic of ISD
> This padding schematic is import in layout XL window using Generate from source command.
> Place pads using placepads command.
> The input pads are placed on the pads space.
> Do auto routing for making connection between pads and layout.
> Final layout after padding is show in fig 11.
Fig 11: Complete layout with padding
Conclusion: the problem of Impact source Determination has resulted in the interest of large number of investigations. In this paper we suggested a approach which could be helpful in impact source determination. The suggested procedure is given in the form of flow charts and diagrams for the better understanding of the concept. The saved files from the virtuoso can be sent to Mosis and other factories for chip fabrication.