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1. CROP SHEAR CONTROL
SYSTEM
This project CROP SHEAR CONTROL
SYSTEM involved the design and development of a shear
control system for M/s. Tata Iron and Steel Company,
Jamshedpur.
Important Events:
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The prototype of the system was tested successfully using a DC
motor.
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Published a paper on “ Design development and implementation of
Crop Shear Control System using Digital Signal Processor", 4th
International Seminar on Power Electronics and Automation,
INTRONICS-99, IEEMA, January, 1999
Brief Description :
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The crop shear control system is developed for cutting the head
and tail ends of a moving hot metal strip to proper shape, required
in steel industries. The shear position is controlled optimally with
respect to the moving sheet, to achieve the required accuracy. Most
effective control is provided by cascading torque, acceleration,
speed and position loops along with feedforward control.
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The control system is implemented using the Digital Signal
Processor TMS320. The DSP based control unit is connected to a PC
through an RS232 communication link. A convenient user interface is
provided in the PC for configuring the system and changing
parameters . The various algorithms for the operation of the
controller are written in ‘C’ and cross-compiled with TMS320 ‘C’
compiler. Broadly the programs are divided into measurement
routines, off line routines and online routines. Measurement
algorithms are processed as timer interrupt routines. Off line and
online programs involve the calculation of feedforward reference
trajectories for acceleration, speed and position of shear. Some of
the computations that can be done before starting the cut are put in
off line routine to save computation time during the online process.
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External interrupt routines are used for initializing the
measurements and starting the online calculations. The online
programs also calculate the Proportional Integral and Derivative
control (PID) law from the predicted error for position control. The
algorithms resident in the DSP also check all the preconditions to
be met for the satisfactory operation of the shear drive system and
thereof positioning of the shear knives to the defined waiting
position, if it is already not in waiting position.
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A user-friendly graphical interface is designed to enter the
required tuning parameters of the system and establish a two-way
communication between PC and DSP system. After entering the required
parameters, the user can initiate the process of cutting, by sending
these values and handing over the control to DSP system. Once the
control is passed to DSP system, the PC get itself switched over to
monitoring mode. Now, the status of initialization of the knives,
their movements etc., will be communicated to PC and are displayed
on the monitor, in the space provided for this purpose. If there is
any problem encountered with those operations (e.g. a switch has to
be turned off), the same is displayed on the screen, with continuous
beep sounds, so that the operator can rectify them. After the
cutting process is over, the data required to plot the trends are
passed from DSP to PC and are stored in appropriate log files
Hardware Specifications Mother Board
| Processor |
TMS320C32 Floating Point DSP |
| External Bus |
32-Bit |
| Memory |
EPROM - 64K to 256K RAM |
| Serial Ports |
1 RS232 & 1 RS485 |
32-bit Timers | 2 |
| Supply Voltage |
+5V |
| Status Display |
5 LEDs |
| Back plane Bus |
VME Compatible (6 expansion slots) |
| Board Size |
Double Euro (160 * 233.3 mm) |
Process Interface
| Digital Inputs |
9; High Speed Opto-Isolated |
| Digital Outputs |
2; Relay Contacts |
| Analog Inputs |
2; 12-bit res. 2000V DC
Isolation |
| Analog
Outputs |
3; 12-bit res. 2000V DC
Isolation |
| External
Interrupts |
3; High Speed
Opto-Isolated |
| Incremental Encoder
Inputs |
2; Quadrature Decoder
Inputs |
| Absolute Encoder
Inputs |
1; 16-bit Gray-code Input
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