Question

Feed forward and feed backward concept is observed in

• A. Winch dyeing machine
• B. Jet dyeing machine
• C. Jigger dyeing machine
• D. Pad- Batch dyeing machine

Hint:

• Feed forward control A control system where information about disturbances or input changes is used to adjust control actions proactively to minimize their impact on the output.
• Feedback control A control system where the output of a process is measured and compared to a setpoint, and the difference (error) is used to adjust control actions.
• Jigger dyeing machine Fabric passes back and forth between rollers through a dyebath. Maintaining constant linear speed and tension is critical as roll diameters change. This requires sophisticated drive controls, which can use both feed forward (based on calculated diameter) and feedback (based on measured tension/speed) strategies. The "feed backward" could also refer to the reversal of the fabric path.

Answer 1

The Correct Option is C

The concepts of "feed forward" and "feed backward" control are related to process automation and control systems, where information from one part of a process is used to adjust parameters in another part (either upstream or downstream). In the context of dyeing machines, this often relates to controlling fabric speed, tension, or liquor application based on measurements or predictions. Let's consider the dyeing machines listed:

• (a) Winch dyeing machine: Fabric in rope form is circulated by a winch (elliptical reel) through a dyebath. Control systems are generally simpler, focused on temperature, time, and winch speed. Sophisticated feed forward/backward control is less typical.
• (b) Jet dyeing machine: Fabric in rope form is circulated by high-velocity jets of dye liquor. Modern jet dyers have advanced controls for flow rate, temperature, fabric speed, and differential pressure. While they use feedback control extensively, "feed forward/backward" as a defining concept for its core operation might refer to specific advanced process optimization strategies.
• (c) Jigger dyeing machine: Fabric is processed in open width, passed back and forth from one roller to another through a small trough of dye liquor at the bottom.
  • Constant tension and speed control are crucial for uniform dyeing on a jigger. As fabric is wound from one batch roller to the other, the diameter of the take-up roller increases and the let-off roller decreases.
  • To maintain constant fabric speed and tension, the rotational speeds of these rollers must be continuously adjusted.
  • Feed forward control can be used where, for example, the known change in diameter is used to proactively adjust motor speeds.
  • Feedback control (e.g., using tension sensors) is also used to fine-tune these speeds.
  • The term "feed backward" might refer to the reversal of fabric direction, or perhaps a control loop where an output affects an earlier stage setting on the next pass. The back-and-forth passage of fabric itself is a form of "feeding backward" then "feeding forward".
  The nature of jigger dyeing, with its need to precisely control speed and tension of rollers whose effective diameters are constantly changing, makes it a prime candidate for employing sophisticated control strategies including feed forward and feedback loops. The concept of reversing direction (fabric feeding forward then backward through the liquor) is inherent.
• (d) Pad-Batch dyeing machine: Fabric is padded with dye liquor and then batched (rolled up) and stored for a period to allow dye fixation (cold pad-batch for reactives). This is a semi-continuous or batch process. Control is mainly at the padding nip (pressure, pick-up) and batching conditions. Feed forward/backward control in the dynamic sense of jigger is less central.

The Jigger dyeing machine, with its reciprocating motion of fabric between two rollers and the need to manage speed and tension precisely as roll diameters change, heavily relies on control systems that can embody "feed forward" (anticipatory control based on diameter changes) and "feed backward" (adjustments based on previous pass or tension feedback, and the literal back-and-forth movement) concepts. \[ \boxed{\text{Jigger dyeing machine}} \]