SuperSmart Crane Controller

SuperSmart Crane SuperSmart Crane ControllerController

Ziyad N. Masoud and Ali H. NayfehZiyad N. Masoud and Ali H. Nayfeh

Department of Engineering Science and MechanicsDepartment of Engineering Science and Mechanics

Virginia Polytechnic Institute Virginia Polytechnic Institute and State Universityand State University

IntroductionIntroduction

– A nonlinear feedback SuperSmart Crane A nonlinear feedback SuperSmart Crane Controller (SSC Controller) has been developed at Controller (SSC Controller) has been developed at Virginia Tech to suppress cargo sway in all types Virginia Tech to suppress cargo sway in all types of commercial and military cranesof commercial and military cranes

– The SSC Controller has been applied to computer The SSC Controller has been applied to computer models of a ship-mounted boom crane, a land-models of a ship-mounted boom crane, a land-based rotary crane, and a 65-ton container cranebased rotary crane, and a 65-ton container crane

– Experimental validation has been performed on Experimental validation has been performed on scaled models of a ship-mounted boom crane and a scaled models of a ship-mounted boom crane and a land-based rotary craneland-based rotary crane

Cargo Ship

LighterVessel

T-ACS

Crane

Ship-Mounted CranesShip-Mounted Cranes

Ship-mounted cranes are used to transfer cargo from large container ships tolighter vessels when deep-water ports are not available

Objective of Ship-Mounted ControlObjective of Ship-Mounted Control

– will suppress cargo swinging and enable cargo will suppress cargo swinging and enable cargo transfer in heavy seas (Sea state 3 and above)transfer in heavy seas (Sea state 3 and above)

– will not require major modifications to existing will not require major modifications to existing crane structurescrane structures

– which can be superimposed on the input of crane which can be superimposed on the input of crane operators operators

– will enable automatic safe landing of cargo on will enable automatic safe landing of cargo on lighter shipslighter ships

Develop an active control system for a ship-Develop an active control system for a ship-mounted crane thatmounted crane that

Control StrategyControl Strategy

• Control of boom luff and slew angles, which Control of boom luff and slew angles, which are already actuated are already actuated

• Use the nonlinear SSC Controller scheme to Use the nonlinear SSC Controller scheme to create nonlinear damping of the payload create nonlinear damping of the payload pendulationspendulations

Worst-Case ScenarioWorst-Case Scenario• Because the roll and pitch motions appear as additive terms in the crane 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 governing equations, the most critical conditions occur when the roll and pitch frequencies are approximately equal to the natural frequency of the cargo frequencies are approximately equal to the natural frequency of the cargo pendulationpendulation– Therefore, we drive the roll and pitch of the ship and the platform at the natural 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 cargofrequency of the cargo pendulation, thereby inducing primary resonance of the cargo• Primary resonance atPrimary resonance at

• Because the heave motion appears as a time-varying coefficient or multiplicative Because the heave motion appears as a time-varying coefficient or multiplicative term in the crane governing equations, the most critical conditions occur when 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 the heave frequency is approximately equal to twice the natural frequency of the cargo pendulationcargo pendulation– Therefore, we drive the heave of the ship and the platform at twice the natural 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 frequency of the cargo pendulation, thereby inducing principal parametric resonance of the cargoof the cargo

• Principal parametric resonance atPrincipal parametric resonance at

Hz192.02 n

Hz096.0n

Computer SimulationComputer Simulation

• The model dimensions The model dimensions are based on the Navy’s are based on the Navy’s T-ACS crane shipT-ACS crane ship

• The model is driven with The model is driven with critical sinusoidal critical sinusoidal excitations (worst-case excitations (worst-case scenario) in roll, heave, scenario) in roll, heave, and pitchand pitch

• The full nonlinear The full nonlinear equations of motion , equations of motion , including the rigid-body including the rigid-body motion of the load, are motion of the load, are solved numericallysolved numerically

Uncontrolled ResponseUncontrolled Response

• At the natural frequency of the cargo pendulation in At the natural frequency of the cargo pendulation in both the roll and pitch modes of motionboth the roll and pitch modes of motion– The roll amplitude is 2º The roll amplitude is 2º – The pitch amplitude is 1º The pitch amplitude is 1º

• At twice the natural frequency of the cargo At twice the natural frequency of the cargo pendulation in the heave motionpendulation in the heave motion– The heave amplitude is 1 ftThe heave amplitude is 1 ft

To simulate the problem of cargo handling in To simulate the problem of cargo handling in moderate to high seas, while hoisting a payload, moderate to high seas, while hoisting a payload, we excited the computer ship model sinusoidallywe excited the computer ship model sinusoidally

Planar ControllersPlanar Controllers

• Most of the current control strategies attempt to Most of the current control strategies attempt to suppress payload pendulations in one planesuppress payload pendulations in one plane

• To simulate the effect of ignoring the other To simulate the effect of ignoring the other pendulation plane, in the following clip, we apply the pendulation plane, in the following clip, we apply the SSC Controller to one pendulation planeSSC Controller to one pendulation plane– The same excitation conditions used in the uncontrolled The same excitation conditions used in the uncontrolled

simulation are applied to the computer model of the crane simulation are applied to the computer model of the crane shipship

Planar Controllers Planar Controllers

• We shift the pitch frequency away from the natural We shift the pitch frequency away from the natural frequency of the payload frequency of the payload

• We keep the rest of the excitation conditions as in the We keep the rest of the excitation conditions as in the uncontrolled simulationuncontrolled simulation

• We command the crane to perform a 90º slewing We command the crane to perform a 90º slewing action and back every 40 secaction and back every 40 sec

Assuming that the pitch excitation frequency is away Assuming that the pitch excitation frequency is away from the natural frequency of the cargo pendulation from the natural frequency of the cargo pendulation and that it should not introduce significant energy to and that it should not introduce significant energy to the cargothe cargo

Remarks on Planar ControllersRemarks on Planar Controllers

• The results of the previous two simulations show that The results of the previous two simulations show that planar controllers are incapable of suppressing planar controllers are incapable of suppressing general payload pendulations general payload pendulations

• Therefore, a full three-dimensional controller is Therefore, a full three-dimensional controller is requiredrequired

3D SSC Controller3D SSC Controller

• The 3D SSC Controller is applied to the craneThe 3D SSC Controller is applied to the crane

• The most critical excitation conditions, as in the The most critical excitation conditions, as in the uncontrolled simulation, are applied to the computer uncontrolled simulation, are applied to the computer model of the crane shipmodel of the crane ship

• The following clip shows the response of the The following clip shows the response of the controlled cargo for a stationary cranecontrolled cargo for a stationary crane


• With the 3D SSC Controller still applied to the With the 3D SSC Controller still applied to the crane, andcrane, and

• The same most critical excitation conditions, as The same most critical excitation conditions, as in the uncontrolled simulation, are applied to in the uncontrolled simulation, are applied to the computer model of the crane shipthe computer model of the crane ship

• The following clip shows the response of the The following clip shows the response of the controlled cargo for a crane performing a 90º controlled cargo for a crane performing a 90º slewing action and back every 40 secslewing action and back every 40 sec

3D SSC Controller 3D SSC Controller (Slewing crane)(Slewing crane)

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

• With the 3D SSC Controller still applied to the With the 3D SSC Controller still applied to the crane, andcrane, and

• The same most critical excitation conditions, The same most critical excitation conditions, as in the uncontrolled simulation, are applied as in the uncontrolled simulation, are applied to the computer model of the crane shipto the computer model of the crane ship

• The following clip shows the response of the The following clip shows the response of the controlled cargo to an initial position controlled cargo to an initial position disturbance of 60ºdisturbance of 60º

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

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

Controlled vs. Uncontrolled Response Controlled vs. Uncontrolled Response (Slewing crane)(Slewing crane)

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

Experimental Experimental DemonstrationDemonstration

• We built a 3 DOF ship-We built a 3 DOF ship-motion simulator platform motion simulator platform – It is capable of performing It is capable of performing

general pitch, roll, and heave general pitch, roll, and heave motionsmotions

• We mounted a 1/24 scale We mounted a 1/24 scale model of a ship-mounted model of a ship-mounted crane on the platformcrane on the platform

• We are using a PC to apply We are using a PC to apply the SSC Controller and drive the SSC Controller and drive the cranethe crane


• The ship simulator platform is excited The ship simulator platform is excited sinusoidally atsinusoidally at – The natural frequency of the cargo pendulation in The natural frequency of the cargo pendulation in

both the roll and pitch modes of motionboth the roll and pitch modes of motion• The roll amplitude is 1º The roll amplitude is 1º • The pitch amplitude is 0.5ºThe pitch amplitude is 0.5º

– Twice the natural frequency of the cargo Twice the natural frequency of the cargo pendulation in the heave motionpendulation in the heave motion• The heave amplitude is 0.5 inThe heave amplitude is 0.5 in

Controlled ResponseControlled Response

• The SSC Controller is activatedThe SSC Controller is activated• The ship simulator platform is excited The ship simulator platform is excited

sinusoidally at sinusoidally at – The natural frequency of the payload pendulum in The natural frequency of the payload pendulum in

both the roll and pitch modes of motion both the roll and pitch modes of motion • The roll amplitude is 1º The roll amplitude is 1º • The pitch amplitude is 0.5º The pitch amplitude is 0.5º

– Twice the natural frequency of the payload Twice the natural frequency of the payload pendulum in the heave motionpendulum in the heave motion• The heave amplitude is 0.5 inThe heave amplitude is 0.5 in

Controlled Response to Larger Controlled Response to Larger Platform MotionsPlatform Motions

• The SSC Controller is activatedThe SSC Controller is activated• The ship simulator platform is still excited The ship simulator platform is still excited

sinusoidally at sinusoidally at – The natural frequency of the payload pendulum in The natural frequency of the payload pendulum in

both the roll and pitch modes of motionboth the roll and pitch modes of motion• The roll amplitude is increased to 2º The roll amplitude is increased to 2º • The pitch amplitude is increased to 1º The pitch amplitude is increased to 1º

– Twice the natural frequency of the payload Twice the natural frequency of the payload pendulum in the heave motionpendulum in the heave motion• The heave amplitude is 0.5 inThe heave amplitude is 0.5 in

Controlled Response to Larger Controlled Response to Larger Platform MotionsPlatform Motions

Controlled Response Controlled Response (Slewing crane)(Slewing crane)

• The SSC Controller is activatedThe SSC Controller is activated

• The ship simulator platform is excited sinusoidally at The ship simulator platform is excited sinusoidally at – The natural frequency of the payload pendulum in both the The natural frequency of the payload pendulum in both the

roll and pitch modes of motionroll and pitch modes of motion• The roll amplitude is 1º The roll amplitude is 1º

• The pitch amplitude is 0.5º The pitch amplitude is 0.5º

– Twice the natural frequency of the payload pendulum in Twice the natural frequency of the payload pendulum in the heave motionthe heave motion

• The heave amplitude is 0.5 inThe heave amplitude is 0.5 in

• After 8 seconds, the crane is commanded to perform a After 8 seconds, the crane is commanded to perform a 90º slewing action every 8 sec90º slewing action every 8 sec

Controlled Response Controlled Response (Slewing crane)(Slewing crane)

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

• The SSC Controller is activatedThe SSC Controller is activated



• The pitch amplitude is 1º The pitch amplitude is 1º



• After 8 seconds, the crane is commanded to perform a After 8 seconds, the crane is commanded to perform a 90º slewing action every 8 sec90º slewing action every 8 sec

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

Performance of the ControllerPerformance of the Controller (in the presence of Initial Conditions)(in the presence of Initial Conditions)

• To simulate an initial disturbance, the SSC Controller To simulate an initial disturbance, the SSC Controller is activated 10 seconds after experiment beginsis activated 10 seconds after experiment begins



• The pitch amplitude is 0.5º The pitch amplitude is 0.5º



Performance of ControllerPerformance of Controller(in presence of Initial Conditions)(in presence of Initial Conditions)

Tower CranesTower Cranes

• The SSC Controller is added The SSC Controller is added to and tested on a scaled to and tested on a scaled model of a tower cranemodel of a tower crane

• The crane is tested in both the The crane is tested in both the rotary and gantry modes of rotary and gantry modes of operationoperation

• A PC is used to apply the A PC is used to apply the controller and drive the cranecontroller and drive the crane

Rotary Mode TestRotary Mode Test

• Maximum Maximum rotational rotational velocity velocity

• Rotational Rotational accelerationacceleration

3 / 20 rad/s

23 /10 rad/s

Gantry Mode TestGantry Mode Test

• Maximum Maximum transverse transverse velocity velocity

• Transverse Transverse accelerationacceleration

8 in/s

216 in/s

Container CraneContainer Crane

Container CranesContainer Cranes

• The SSC Controller was applied to a full-scale The SSC Controller was applied to a full-scale computer model of a container cranecomputer model of a container crane

• The combined weight of the container and the The combined weight of the container and the spreader bar is 80 tonsspreader bar is 80 tons

• Three controlled and uncontrolled loading and Three controlled and uncontrolled loading and unloading cases were simulatedunloading cases were simulated

• The controller was tuned to meet the Japanese The controller was tuned to meet the Japanese standardsstandards– The sway of the hoisted load must drop to less than 50mm The sway of the hoisted load must drop to less than 50mm

within 5 seconds after the trolley stopswithin 5 seconds after the trolley stops

Case 1Case 1

• A container is moved from a truck 35m below the A container is moved from a truck 35m below the trolley to a waiting shiptrolley to a waiting ship

• The final position on the ship is 50m away from the The final position on the ship is 50m away from the trucktruck

• The container is hoisted 15m in the first 10 seconds The container is hoisted 15m in the first 10 seconds of the transport maneuverof the transport maneuver

• The trolley covers the 50m distance in 21.5 secondsThe trolley covers the 50m distance in 21.5 seconds• The operator input commands are step accelerations The operator input commands are step accelerations

and decelerations with a rise time of 200msand decelerations with a rise time of 200ms

Case 1: Case 1: Commanded Cargo TrajectoryCommanded Cargo Trajectory

Case 1:Case 1:Commanded Traverse AccelerationCommanded Traverse Acceleration

Case 1:Case 1:Commanded Hoist AccelerationCommanded Hoist Acceleration

Uncontrolled SimulationUncontrolled Simulation

• The animation is The animation is twice as fast as twice as fast as

the actual speedthe actual speed

Controlled SimulationControlled Simulation



Case 1: Cargo MotionCase 1: Cargo Motion

Case 1: Cargo SwayCase 1: Cargo Sway

Case 1:Case 1:A Zoom on Controlled Cargo SwayA Zoom on Controlled Cargo Sway

Case 1:Case 1:Cargo Sway Cargo Sway (Relative to Trolley)(Relative to Trolley)

Case 1:Case 1:A Zoom on Cargo Sway A Zoom on Cargo Sway (Relative to Trolley)(Relative to Trolley)

Case 1: Trolley VelocityCase 1: Trolley Velocity

Case 1: Trolley AccelerationCase 1: Trolley Acceleration

Case 1: Trolley JerkCase 1: Trolley Jerk

Case 1: Tension in the CablesCase 1: Tension in the Cables

Case 1:Case 1:Horizontal Force on TrolleyHorizontal Force on Trolley (Caused by (Caused by Cable Tensions)Cable Tensions)

Case 2Case 2

• A container is moved from a position 20m below the A container is moved from a position 20m below the trolley on a ship to a waiting trucktrolley on a ship to a waiting truck

• The truck is 50m away from the container position on The truck is 50m away from the container position on the shipthe ship

• The trolley covers the 50m distance in 21.5 seconds.The trolley covers the 50m distance in 21.5 seconds.• After 12 seconds from the start of the transport After 12 seconds from the start of the transport

maneuver, the operator begins lowering the container. maneuver, the operator begins lowering the container. • The container is deposited on the truck after 28.5 The container is deposited on the truck after 28.5

second from the start of the maneuversecond from the start of the maneuver• The operator input commands are step accelerations The operator input commands are step accelerations

and decelerations with a rise time of 200msand decelerations with a rise time of 200ms

Case 2:Case 2:Commanded Cargo TrajectoryCommanded Cargo Trajectory

Case 2:Case 2:A Zoom on Cargo SwayA Zoom on Cargo Sway (Relative to Trolley)(Relative to Trolley)

Case 2:Case 2:Horizontal Force on TrolleyHorizontal Force on Trolley (Caused by (Caused by Cable Tensions)Cable Tensions)

Case 3Case 3

• A container is moved from a position 35m below the trolley on A container is moved from a position 35m below the trolley on a ship to a waiting trucka ship to a waiting truck

• The truck is 50m away from the container position on the shipThe truck is 50m away from the container position on the ship• The trolley covers the 50m distance in 21.5 secondsThe trolley covers the 50m distance in 21.5 seconds• The container is hoisted 15m in the first 10 seconds of the The container is hoisted 15m in the first 10 seconds of the

maneuvermaneuver• Twelve seconds later, the operator begins lowering the containerTwelve seconds later, the operator begins lowering the container• The container is deposited on the truck after 28.5 seconds from The container is deposited on the truck after 28.5 seconds from

the start of the maneuverthe start of the maneuver• The operator input commands are step accelerations and The operator input commands are step accelerations and

decelerations with a rise time of 200msdecelerations with a rise time of 200ms

Case 3:Case 3:Commanded Cargo TrajectoryCommanded Cargo Trajectory

Case 3:Case 3:A Zoom on Cargo Sway A Zoom on Cargo Sway (Relative to Trolley)(Relative to Trolley)

Case 3:Case 3:Horizontal Force on Trolley Horizontal Force on Trolley (Caused by (Caused by the Cable Tensions)the Cable Tensions)

Concluding RemarksConcluding Remarks

• The nonlinear SSC Controller is an effective means The nonlinear SSC Controller is an effective means of reducing cargo pendulations in crane systemsof reducing cargo pendulations in crane systems

• The SSC Controller is applicable to the all common The SSC Controller is applicable to the all common types of cranestypes of cranes

• The SSC Controller is capable of absorbing base The SSC Controller is capable of absorbing base excitation energy before reaching the hoisted cargoexcitation energy before reaching the hoisted cargo

• Significant reductions in the pendulation angles can Significant reductions in the pendulation angles can be achieved with relatively small control inputsbe achieved with relatively small control inputs

• Most existing crane actuators can be used for the Most existing crane actuators can be used for the purpose of applying the controller purpose of applying the controller

• Only a few sensors and a PC (chip) are neededOnly a few sensors and a PC (chip) are needed

Concluding Remarks Concluding Remarks (cont.)(cont.)

• The cost of the SSC Controller system is low because it The cost of the SSC Controller system is low because it does not require modifications to existing crane does not require modifications to existing crane structuresstructures

• The system can be automated and hence the operators The system can be automated and hence the operators do not need to use pedals do not need to use pedals

• The SSC Controller is superimposed on the commands The SSC Controller is superimposed on the commands of crane operators of crane operators

• The SSC Controller is capable of absorbing the inertial The SSC Controller is capable of absorbing the inertial excitation energy resulting from the operator commandsexcitation energy resulting from the operator commands

Concluding Remarks Concluding Remarks (cont.)(cont.)

• The end point of the transport maneuver need not be The end point of the transport maneuver need not be pre-definedpre-defined

• The SSC Controller is capable of handling an The SSC Controller is capable of handling an operator stop command at any random timeoperator stop command at any random time

Contact InformationContact Information

• Ali NayfehAli Nayfeh– Department of Engineering Science and Mechanics, MC 0219Department of Engineering Science and Mechanics, MC 0219– Virginia Polytechnic Institute and State UniversityVirginia Polytechnic Institute and State University– Blacksburg, VA 24061Blacksburg, VA 24061– Phone: (540) 231-5453Phone: (540) 231-5453– Fax: (540) 231-2290Fax: (540) 231-2290– Email: Email: [email protected]@vt.edu– http://www.esm.vt.edu/~anayfeh/http://www.esm.vt.edu/~anayfeh/

• Ziyad MasoudZiyad Masoud– Department of Engineering Science and Mechanics, MC 0219Department of Engineering Science and Mechanics, MC 0219– Virginia Polytechnic Institute and State UniversityVirginia Polytechnic Institute and State University– Blacksburg, VA 24061Blacksburg, VA 24061– Phone: (540) 231-1227Phone: (540) 231-1227– Fax: (540) 231-2290Fax: (540) 231-2290– Email: Email: [email protected]@vt.edu

mailto:[email protected]

http://www.esm.vt.edu/~anayfeh/

mailto:[email protected]

SuperSmart Crane Controller

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