CASE STUDIES IN MECHATRONIC SYSTEMS:
Automatic Car Park System:
Consider the barrier parking scheme operated by the coin.
The system's primary condition is that, if the right cash (coin) is placed in the collection box, the in-barrier should be unlocked to allow the vehicle inside.
If the vehicle is identified at the car park side of the obstacle, the out door must be unlocked to allow the vehicle outside.
The automatic parking barrier along with the lifting and lowering system When the current passes through the solenoid A & the piston in the cylinder expands upward and allows the obstacle to spin around its pivot, thus raising the obstacle to enable the inside of the vehicle.
The lever on the solenoid valve allows the links open and thus returns the valve to its original position when the current passes through the solenoid A ceases.
The piston in the cylinder shifts backwards when the fluid passes through solenoid B, causing the obstacle to fall.
Limit buttons are used to identify when and when the obstacle is down.
This control can be controlled by PLC
X400 – coin operated switch at entrance to car park
X401 – switch activated when entrance barrier is out
X402 – switch activated when entrance barrier is down
X403 – switch activated when car at exit barrier
X404 – switch activated when exit barrier is -up
X405 – switch activated when exit barrier is down
Y430 – solenoid on valve A for entrance barrier
Y43 1 – solenoid on valve B for entrance barrier
Y432 – solenoid on valve A for exit barrier
Y433 – solenoid on valve B for exit barrier
Six outputs (X400 to X405) are needed for the PLC to detect the six limit switch location, namely coin-operated button, input barrier up switch, output barrier up switch, output barrier down switch Whenever a button is operated, the respective outputs are given with 0V input and otherwise the outputs receive + 24v signal. The operation of the two solenoid valves A and B requires four inputs (Y430 to Y433).
Program:
LD X400
OR Y430
ANI M100
ANI Y431
OUT Y430
LD X401
OUT T450
K 10
LD T450
OUT M100
LD M100
OR Y431
ANI X402
ANI Y430
OUT Y431
LD X403
OR Y432
ANI M101
ANI Y433
OUT Y432
LD X404
OUT T451
K 10
LD | T45 1 |
OUT | M101 |
LD | M101 |
OR | Y433 |
ANI | X405 |
ANI | Y432 |
OUT | Y433 |
END
Assume a 10-second interval for the vehicle to enter the obstacle and exit the obstacle. These time gaps supplied by T450 and T451 respectively energizing their internal relays.
