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Question 5 Four double acting pneumatic cylinders, namely A, B, C and D, are used to assemble a component in a production process. An electro-pneumatic circuit which are controlled by double solenoid valves is required for the application. The cylinder motion sequence is as below: Step 1. (b) 2. 3. 4. 5. 6. 7. 8. 9. Description Initially cylinder A are in its extension state while cylinder B, C and D are in their retraction states. When a pushbutton (Normally Open type) is pressed momentarily, cylinder A retracts to its fully retracted position while B extends to its fully extended position simultaneously Next, cylinder B retracts to its fully extended position. Next, cylinder D extends to its fully retracted position. Next, cylinder C extends to its fully extended position. Next, cylinder C retracts to its fully retracted position. Next, cylinder D retracts to its fully retracted position. Lastly, cylinder A extends to its fully retracted position. System halts and await for another input signal to run the above cycle again. Other requirements: (i) Each step of motion can only be started right after the previous step motion ended (ii) Every cylinder motion is speed adjustable Reed switches or micro-switches or IR sensors, with NO and NC contacts, may be used for position sensors. (a) Group the motion sequence by the Cascade method. Draw the electro-pneumatic sub-circuit of the system. (c) By using the Cascade method, design an electrical ladder diagram for driving the above sequence of the four pneumatic cylinders. (6 marks) (12 marks) (22 marks)