PLC Automation Systems

Problem Statement

The core problem addressed was the efficient control of traffic at a four-way intersection, considering both normal and after-hours operation. The system needed to manage traffic flow smoothly by adapting to varying conditions based on a state transition diagram and user-friendly HMI controls.

Components & HMI

Inputs: System Turn On/Off (B1 - latching), After Hours Operation (B2 - latching).

Outputs: 8 traffic lights (2 pairs for each of the 4 intersections: L1, L2, L3, L4), Traffic system working indicator.

HMI Design: The HMI provided a visual representation of the intersection with all 8 traffic lights, a system status indicator, and three control buttons: "Start the system," "Stop the system," and "After Hours."

Operational Logic & Objectives

• Normal Operation: Designed to follow a specific timing cycle: State 1 - Red light (90s); State 2 - Yellow light (5s); State 3 - Green light (120s), followed by the green light flashing at 1Hz for 5 seconds before repeating the cycle.
• After-Hours Operation: When activated (B2=1), all traffic lights transition to flashing yellow at 1Hz. The system was designed to revert to normal operation if B2 is deactivated and the system is (re)started.
• Advanced Lights (Research): Explored the potential use of FCT Push/Pull Load Cells for vehicle detection to create more adaptive light timings, though this was a research component not fully implemented.

Observations & Challenges

• An issue was noted where the system did not correctly revert to the normal state from after-hours mode if stopped and then restarted; lights would turn off directly.
• Full implementation of a Real-Time Clock (RTC) for automatic after-hours switching and the sensor-based advanced light system was not completed.
• A bug was observed where, after the 120-second green light phase, all lights could potentially turn on, which could lead to hazardous road conditions.

Problem Statement

The objective was to create an interactive and engaging toy claw machine simulation. This involved designing the control system for claw movement (X, Y, Z axes), gripper operation, game timing (90 seconds per play), and user feedback via an HMI.

Gameplay, Components & HMI

Game Rules & Sequence: Coin insertion (simulated by button S0) activates the game. The player has 90 seconds to maneuver the claw. Pressing the "Start Game" button (B0) initiates the claw's automated sequence: open, descend, close, ascend, move to drop-off, and release. "Winner" or "Game Over" messages are displayed based on outcome.

Inputs: Game Start Button (B0 - momentary), Input Coin OK (S0 - momentary), X/Y motion joystick inputs (X2, X3, X4, X5).

Outputs: X_Motor_Right/Left, Y_Motor_Right/Left, Z_Motor_Up/Down, Gripper_Open/Close.

Internal Variables: Total_Number_of_Games_Played, Total_Number_of_Wins, Date_and_Time_of_Last_Win.

HMI Design: Displayed joystick buttons for four directions, a "START GAME" button, remaining time display, game status messages (e.g., "GAME IS ON!", "CONGRATS!", "NO PRIZE :(" with Spongebob/Mike Wazowski images), and "Prize: ON/OFF" indicators.

Observations & Challenges

• The "time left" clock did not reset correctly for subsequent game rounds.
• The "Date_of_Last_Win" was not displayed in a proper date format in the animation table (though counted internally).
• Joystick buttons were designed as hold-to-move, requiring continuous pressing.