SuperSmart Crane Controller

1. SuperSmart Crane Controller Ziyad N. Masoud and Ali H. Nayfeh Department of Engineering Science and Mechanics Virginia Polytechnic Institute and State University

2. Introduction • A nonlinear feedback SuperSmart Crane Controller (SSC Controller) has been developed at Virginia Tech to suppress cargo sway in all types of commercial and military cranes • The SSC Controller has been applied to computer models of a ship-mounted boom crane, a land-based rotary crane, and a 65-ton container crane • Experimental validation has been performed on scaled models of a ship-mounted boom crane and a land-based rotary crane

3. Ship-Mounted Cranes Crane Cargo Ship Lighter Vessel T-ACS Ship-mounted cranes are used to transfer cargo from large container ships to lighter vessels when deep-water ports are not available

4. Objective of Ship-Mounted Control Develop an active control system for a ship-mounted crane that • will suppress cargo swinging and enable cargo transfer in heavy seas (Sea state 3 and above) • will not require major modifications to existing crane structures • which can be superimposed on the input of crane operators • will enable automatic safe landing of cargo on lighter ships

5. Control Strategy • Control of boom luff and slew angles, which are already actuated • Use the nonlinear SSC Controller scheme to create nonlinear damping of the payload pendulations

6. Worst-Case Scenario • Because the roll and pitch motions appear as additive terms in the crane governing equations, the most critical conditions occur when the roll and pitch frequencies are approximately equal to the natural frequency of the cargo pendulation • Therefore, we drive the roll and pitch of the ship and the platform at the natural frequency of the cargo pendulation, thereby inducing primary resonance of the cargo • Primary resonance at • Because the heave motion appears as a time-varying coefficient or multiplicative term in the crane governing equations, the most critical conditions occur when the heave frequency is approximately equal to twice the natural frequency of the cargo pendulation • Therefore, we drive the heave of the ship and the platform at twice the natural frequency of the cargo pendulation, thereby inducing principal parametric resonance of the cargo • Principal parametric resonance at

7. Computer Simulation • The model dimensions are based on the Navy’s T-ACS crane ship • The model is driven with critical sinusoidal excitations (worst-case scenario) in roll, heave, and pitch • The full nonlinear equations of motion , including the rigid-body motion of the load, are solved numerically

8. Uncontrolled Response • At the natural frequency of the cargo pendulation in both the roll and pitch modes of motion • The roll amplitude is 2º • The pitch amplitude is 1º • At twice the natural frequency of the cargo pendulation in the heave motion • The heave amplitude is 1 ft To simulate the problem of cargo handling in moderate to high seas, while hoisting a payload, we excited the computer ship model sinusoidally

9. Uncontrolled Response

10. Planar Controllers • Most of the current control strategies attempt to suppress payload pendulations in one plane • To simulate the effect of ignoring the other pendulation plane, in the following clip, we apply the SSC Controller to one pendulation plane • The same excitation conditions used in the uncontrolled simulation are applied to the computer model of the crane ship

11. Planar Controllers

12. Planar Controllers Assuming that the pitch excitation frequency is away from the natural frequency of the cargo pendulation and that it should not introduce significant energy to the cargo • We shift the pitch frequency away from the natural frequency of the payload • We keep the rest of the excitation conditions as in the uncontrolled simulation • We command the crane to perform a 90º slewing action and back every 40 sec

13. Planar Controllers

14. Remarks on Planar Controllers • The results of the previous two simulations show that planar controllers are incapable of suppressing general payload pendulations • Therefore, a full three-dimensional controller is required

15. 3D SSC Controller • The 3D SSC Controller is applied to the crane • The most critical excitation conditions, as in the uncontrolled simulation, are applied to the computer model of the crane ship • The following clip shows the response of the controlled cargo for a stationary crane

16. 3D SSC Controller

17. 3D SSC Controller • With the 3D SSC Controller still applied to the crane, and • The same most critical excitation conditions, as in the uncontrolled simulation, are applied to the computer model of the crane ship • The following clip shows the response of the controlled cargo for a crane performing a 90º slewing action and back every 40 sec

18. 3D SSC Controller (Slewing crane)

19. Performance of 3D SSC Controller (in the Presence of Initial Conditions IC’s) • With the 3D SSC Controller still applied to the crane, and • The same most critical excitation conditions, as in the uncontrolled simulation, are applied to the computer model of the crane ship • The following clip shows the response of the controlled cargo to an initial position disturbance of 60º

20. Performance of 3D SSC Controller(in the Presence of Initial Conditions IC’s)

21. Controlled vs. Uncontrolled Response (Fixed crane orientation)

22. Controlled vs. Uncontrolled Response (Fixed crane orientation)

23. Controlled vs. Uncontrolled Response (Slewing crane)

24. Controlled vs. Uncontrolled Response (Slewing crane)

25. Controlled vs. Uncontrolled Response(Performance in Presence of Initial Conditions)

26. Experimental Demonstration • We built a 3 DOF ship-motion simulator platform • It is capable of performing general pitch, roll, and heave motions • We mounted a 1/24 scale model of a ship-mounted crane on the platform • We are using a PC to apply the SSC Controller and drive the crane

27. Uncontrolled Response • The ship simulator platform is excited sinusoidally at • The natural frequency of the cargo pendulation in both the roll and pitch modes of motion • The roll amplitude is 1º • The pitch amplitude is 0.5º • Twice the natural frequency of the cargo pendulation in the heave motion • The heave amplitude is 0.5 in

28. Uncontrolled Response

29. Controlled Response • The SSC Controller is activated • The ship simulator platform is excited sinusoidally at • The natural frequency of the payload pendulum in both the roll and pitch modes of motion • The roll amplitude is 1º • The pitch amplitude is 0.5º • Twice the natural frequency of the payload pendulum in the heave motion • The heave amplitude is 0.5 in

30. Controlled Response

31. Controlled Response to Larger Platform Motions • The SSC Controller is activated • The ship simulator platform is still excited sinusoidally at • The natural frequency of the payload pendulum in both the roll and pitch modes of motion • The roll amplitude is increased to 2º • The pitch amplitude is increased to 1º • Twice the natural frequency of the payload pendulum in the heave motion • The heave amplitude is 0.5 in

32. Controlled Response to Larger Platform Motions

33. Controlled Response (Slewing crane) • The SSC Controller is activated • The ship simulator platform is excited sinusoidally at • The natural frequency of the payload pendulum in both the roll and pitch modes of motion • The roll amplitude is 1º • The pitch amplitude is 0.5º • Twice the natural frequency of the payload pendulum in the heave motion • The heave amplitude is 0.5 in • After 8 seconds, the crane is commanded to perform a 90º slewing action every 8 sec

34. Controlled Response (Slewing crane)

35. Controlled Response to Larger Platform Motions (Slewing crane) • The SSC Controller is activated • The ship simulator platform is excited sinusoidally at • The natural frequency of the payload pendulum in both the roll and pitch modes of motion • The roll amplitude is 2º • The pitch amplitude is 1º • Twice the natural frequency of the payload pendulum in the heave motion • The heave amplitude is 0.5 in • After 8 seconds, the crane is commanded to perform a 90º slewing action every 8 sec

36. Controlled Response to Larger Platform Motions (Slewing crane)

37. Performance of the Controller(in the presence of Initial Conditions) • To simulate an initial disturbance, the SSC Controller is activated 10 seconds after experiment begins • The ship simulator platform is excited sinusoidally at • The natural frequency of the payload pendulum in both the roll and pitch modes of motion • The roll amplitude is 1º • The pitch amplitude is 0.5º • Twice the natural frequency of the payload pendulum in the heave motion • The heave amplitude is 0.5 in

38. Performance of Controller(in presence of Initial Conditions)

39. Tower Cranes • The SSC Controller is added to and tested on a scaled model of a tower crane • The crane is tested in both the rotary and gantry modes of operation • A PC is used to apply the controller and drive the crane

40. Rotary Mode Test • Maximum rotational velocity • Rotational acceleration

41. Uncontrolled Response

42. Controlled Response

43. Gantry Mode Test • Maximum transverse velocity • Transverse acceleration

44. Uncontrolled Response

45. Controlled Response

46. Container Crane

47. Container Cranes • The SSC Controller was applied to a full-scale computer model of a container crane • The combined weight of the container and the spreader bar is 80 tons • Three controlled and uncontrolled loading and unloading cases were simulated • The controller was tuned to meet the Japanese standards • The sway of the hoisted load must drop to less than 50mm within 5 seconds after the trolley stops

48. Case 1 • A container is moved from a truck 35m below the trolley to a waiting ship • The final position on the ship is 50m away from the truck • The container is hoisted 15m in the first 10 seconds of the transport maneuver • The trolley covers the 50m distance in 21.5 seconds • The operator input commands are step accelerations and decelerations with a rise time of 200ms

49. Case 1: Commanded Cargo Trajectory

50. Case 1:Commanded Traverse Acceleration