Welding Robot Control for Automotive

PROGRAM PLC_CONTROL_LOGIC_EXAMPLE
VAR
    // Inputs
    start_button : BOOL;
    stop_button : BOOL;
    system_ready : BOOL;
    error_detected : BOOL;

    // Outputs
    motor_run : BOOL;
    alarm_signal : BOOL;

    // Internal State
    system_state : INT := 0; // 0=Idle, 1=Running, 2=Error
    runtime_counter : INT := 0;


    // Production Metrics
    Takt_Time : TIME := T#60s;  // Target time per unit
    Cycle_Start_Time : TIME;
    Actual_Cycle_Time : TIME;
    Cycle_Time_OK : BOOL;

    // OEE (Overall Equipment Effectiveness) Tracking
    Availability_Percent : REAL;
    Performance_Percent : REAL;
    Quality_Percent : REAL;
    OEE_Percent : REAL;

    // Production Counters
    Units_Produced_Shift : INT := 0;
    Good_Parts_Count : INT := 0;
    Reject_Parts_Count : INT := 0;
    Rework_Parts_Count : INT := 0;

    // Downtime Tracking
    Downtime_Seconds : INT := 0;
    Downtime_Reason : STRING[50];
    Last_Downtime_Start : DATE_AND_TIME;

    // Andon System
    Andon_Status : INT;  // 0=Green, 1=Yellow, 2=Red
    Line_Stop_Request : BOOL;
    Material_Shortage : BOOL;
    Quality_Issue : BOOL;
    Maintenance_Required : BOOL;

    // Just-In-Time Integration
    Upstream_Buffer_Count : INT;
    Downstream_Buffer_Count : INT;
    Material_Call_Signal : BOOL;

    // Quality Gates
    Vision_Inspection_Pass : BOOL;
    Torque_Verification_Pass : BOOL;
    Dimension_Check_Pass : BOOL;
    All_Quality_Checks_Pass : BOOL;
END_VAR

// ==========================================
// BASE APPLICATION LOGIC
// ==========================================

CASE system_state OF
    0: // Idle state
        motor_run := FALSE;
        alarm_signal := FALSE;

        IF start_button AND system_ready AND NOT error_detected THEN
            system_state := 1;
        END_IF;

    1: // Running state
        motor_run := TRUE;
        alarm_signal := FALSE;
        runtime_counter := runtime_counter + 1;

        IF stop_button OR error_detected THEN
            system_state := 2;
        END_IF;

    2: // Error state
        motor_run := FALSE;
        alarm_signal := TRUE;

        IF stop_button AND NOT error_detected THEN
            system_state := 0;
            runtime_counter := 0;
        END_IF;
END_CASE;

// ==========================================
// AUTOMOTIVE SPECIFIC LOGIC
// ==========================================

    // Takt Time Monitoring for Lean Production
    IF Cycle_State = CYCLE_START THEN
        Cycle_Start_Time := CURRENT_TIME();
    ELSIF Cycle_State = CYCLE_COMPLETE THEN
        Actual_Cycle_Time := CURRENT_TIME() - Cycle_Start_Time;
        Cycle_Time_OK := (Actual_Cycle_Time <= Takt_Time);

        IF NOT Cycle_Time_OK THEN
            Andon_Status := 1;  // Yellow - Behind takt
        END_IF;
    END_IF;

    // OEE Calculation
    // Availability = (Operating Time - Downtime) / Operating Time
    Availability_Percent := ((Shift_Time - Downtime_Seconds) / Shift_Time) * 100.0;

    // Performance = (Actual Production / Target Production) * 100
    Performance_Percent := (Units_Produced_Shift / Target_Units_Shift) * 100.0;

    // Quality = (Good Parts / Total Parts) * 100
    IF Units_Produced_Shift > 0 THEN
        Quality_Percent := (Good_Parts_Count / Units_Produced_Shift) * 100.0;
    END_IF;

    // OEE = Availability × Performance × Quality
    OEE_Percent := (Availability_Percent * Performance_Percent * Quality_Percent) / 10000.0;

    // Andon Board Control - Visual Management
    IF Emergency_Stop OR Critical_Fault THEN
        Andon_Status := 2;  // Red - Line stop
        Downtime_Reason := 'EMERGENCY_STOP';

    ELSIF Material_Shortage THEN
        Andon_Status := 2;  // Red - Material needed
        Line_Stop_Request := TRUE;
        Downtime_Reason := 'MATERIAL_SHORTAGE';

    ELSIF Quality_Issue THEN
        Andon_Status := 1;  // Yellow - Quality alert
        Downtime_Reason := 'QUALITY_ISSUE';

    ELSIF Maintenance_Required THEN
        Andon_Status := 1;  // Yellow - Maintenance needed

    ELSE
        Andon_Status := 0;  // Green - Normal operation
    END_IF;

    // Just-In-Time Material Pull System
    IF Upstream_Buffer_Count < Min_Buffer_Level THEN
        Material_Call_Signal := TRUE;
        // Signal upstream process to send material
    END_IF;

    IF Downstream_Buffer_Count > Max_Buffer_Level THEN
        Production_Enable := FALSE;
        // Stop production to prevent overproduction (muda)
    END_IF;

    // Quality Gate Verification
    All_Quality_Checks_Pass := Vision_Inspection_Pass
                               AND Torque_Verification_Pass
                               AND Dimension_Check_Pass;

    IF NOT All_Quality_Checks_Pass THEN
        Reject_Parts_Count := Reject_Parts_Count + 1;
        Quality_Issue := TRUE;
        // Activate reject station
    ELSE
        Good_Parts_Count := Good_Parts_Count + 1;
    END_IF;

    Units_Produced_Shift := Good_Parts_Count + Reject_Parts_Count;

// ==========================================
// AUTOMOTIVE SAFETY INTERLOCKS
// ==========================================

    // Production Enable Conditions
    Production_Allowed := NOT Line_Stop_Request
                          AND NOT Material_Shortage
                          AND (Andon_Status <> 2)
                          AND (Downstream_Buffer_Count < Max_Buffer_Level)
                          AND NOT Emergency_Stop;

    // Quality Interlock
    IF NOT All_Quality_Checks_Pass THEN
        // Part routed to reject bin automatically
        Part_Accept_Gate := FALSE;
        Part_Reject_Gate := TRUE;
    END_IF;

    // Cycle Time Violation Alert
    IF Actual_Cycle_Time > (Takt_Time * 1.1) THEN
        // 10% over takt time triggers investigation
        Cycle_Time_Alarm := TRUE;
    END_IF;