3 DOF Crane

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Hands-on Way to Study Crane Control Concepts

The Quanser 3 DOF Crane experiment helps teach students about the dynamics and control challenges involved in operating a tower crane, one of the most widely deployed industrial platforms, and how to implement advanced controls to lower crane’s operating times and improve productivity. Students learn how to:

  • design a PID-based feedback system to control the height of the payload
  • develop a state-feedback control system to control the position of the trolley, while keeping the payload swings at minimum
  • design a feedback algorithm to rotate the tower to a desired angle
  • implement developed controllers on the 3 DOF Crane system and observe its performance

In addition to teaching control concepts, the 3 DOF Crane can be used for research in various areas, including nonlinear control, robust control and fuzzy logic.

How It Works

The 3 DOF Crane has the same components as a real tower crane - the vertical tower, or mast, the horizontal jib that sits on top of the tower, and the payload that moves up and down.

The tower rotates in either direction using a high quality Maxon DC motor through a harmonic gearbox. This allows for high torques to be applied with minimal backlash. Two limit switches detect when the tower has reached its limits. If the tower surpasses either limit switch, two cut-off diodes stop the motor, ensuring safe operation of the experiment.

The trolley suspended underneath the jib is fastened onto a linear guide and actuated using geared motor and lead-screw assembly. This allows the trolley to move along the jib smoothly and precisely. Two limit switches installed at each end of jib detect when the trolley has reached its end limits. The trolley has its own MICROMO DC motor that is fixed to pulley/spool system to move the payload vertically up and down. A limit switch underneath the trolley, where the steel wire is dispensed, detects when the payload has reached the top position.

High-resolution encoders precisely measure positions of the rotary tower, the linear trolley, and the vertical payload. The deflection of the payload is also measured using encoders though an instrumented 2 DOF gimbal.

Quanser-developed Courseware Included

The 3 DOF Crane comes with Quanser-developed courseware. A comprehensive User Manual, pre-designed controllers and a dynamic model allow you to get your lab running faster, saving months of time typically required to develop lab materials.

  • High-resolution optical encoders for precise position measurements
  • Trolley and payload driven by high-quality MICROMO DC motors
  • Tower actuated by high quality Maxon DC motor
  • Low backlash harmonic drive used for tower
  • Limit switches to detect when the tower, trolley, and payload have reached their limits
  • Cut-off diodes disable the tower motor when its limits are reached
  • Precise, stiff and heavy-duty machined components
  • Fully compatible with MATLAB®/Simulink® and QUARC® control software
  • Sample model and control design documented and derived in Maple™ worksheet
  • Open architecture design, allowing users to design their own controller
Tower base dimensions (L x W x H) 40.5 cm x 40.5 cm x 1 cm    
Tower height (base plate to top) 120 cm    
Jib length 121 cm    
Crane mass 16 kg    
Trolley lead screw pitch 1.27 cm/rev    
Encoder count resolution 4096 counts/rev    
Effective tower angle resolution 8.79 x 10-4 deg    
Effective trolley linear position resolution 8.38 x 10-7 m    
Effective payload linear position resolution 7.83 x 10-7 m    
Effective payload gimbal deflection angle resolution 0.0879 deg    
Tower angle range ± 155 deg    
Motor resistance 11.5 W (tower) 6.8 W (trolley) 7.1 W (payload)
Motor current – torque constant 0.119 N.m/A (tower) 0.0396 N.m/A (trolley) 0.0261 N.m/A (payload)
Motor output power 90 W (tower) 20.6 W (trolley) 19 W (payload)
Motor maximum continuous current 0.962 A (tower) 0.79 A (trolley) 0.72 A (payload)
Motor gearbox ratio 100 (tower) 3.7 (trolley) 14 (payload)

Topics included in the Quanser-developed courseware:

  • Derivation of simple dynamic model
  • PID control design
  • LQR control design
  • State-space representation (for rotary and linear gantry subsystems)
  • Transfer function representation (for payload subsystem)
  • State-feedback control
  • Control parameter tuning
The 3 DOF Crane can be used to teach also other topics not included in the Quanser-developed courseware.

To set up your 3 DOF Crane workstation, you need additional components. Quanser engineers recommend:

for MATLAB®/Simulink® users  
1x QPIDe data acquisition device  
1x AMPAQ-L4 linear current amplifier²  
QUARC real-time control software  

² alternatively, you can use two AMPAQ-L2 amplifiers

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