RTG Anti‑Sway Control

Overview

RTG Anti-Sway Control is a closed-loop control retrofit that suppresses spreader pendulum motion on Rubber-Tyred Gantry cranes. By measuring sway angle with an IMU on the spreader head and modulating trolley acceleration in real time, the system cancels the swing before the operator even sees it — letting cranes lift, traverse and drop containers 15–25% faster while still landing within a few centimetres.

Bolt-on retrofit for almost any RTG (Konecranes, Kalmar, ZPMC, Liebherr, Mitsui). Operator keeps full manual override; auto-mode does the damping invisibly.

• Cuts cycle time 15–25% — faster traverse without end-of-move sway settling
• Sub-2 cm drop accuracy — consistent stacking, less corner-cast damage
• SIL-2 / IEC 61508 compliant control loop with operator override
• Retrofit-friendly — mounts on existing trolley drives, no structural changes

How It Works

1. IMU on spreader head measures sway angle and angular velocity at 100–200 Hz, transmitted to the cab over CAN or fibre.
2. Trolley encoder + load cell feed the controller the actual position, velocity and current container mass for pendulum-length compensation.
3. PID + feed-forward controller at 25 Hz computes a velocity profile correction; it briefly accelerates / decelerates the trolley in counter-phase to the sway.
4. Trolley VFD takes corrected commands — net result: spreader arrives at target with near-zero residual sway.
5. Operator HMI shows live sway angle, auto/manual toggle, cycle-time delta, and per-shift statistics.

Features

• Adaptive gain — controller re-tunes based on cable length and container mass
• Feed-forward shaping — predicts and pre-compensates trolley accel profile
• Auto / manual / hybrid modes — operator can override or blend at any moment
• Skew & list compensation — correct for asymmetric loads and crooked containers
• Anti-collision interlock — integrates with stack-profile / proximity sensors
• Trainer mode — ghost trace of "ideal" vs operator manual move for coaching
• OTA tuning — push new gain profiles to the fleet from a central console
• Telemetry export — per-move sway, cycle and accuracy data to RTG telemetry stack

Use Cases

• Container terminals — retrofit existing RTG fleet to gain 15–25% productivity without buying new cranes
• New-build cranes — factory-fit anti-sway from day one
• Operator skill levelling — novice operators perform like veterans on cycle time
• Insurance / damage reduction — fewer corner-cast strikes, fewer damaged containers
• Night / poor-visibility shifts — auto-mode keeps productivity steady when sight cues are limited
• Adjacent equipment — STS quay cranes, mobile harbour cranes, ship-loaders use the same control core

Specifications

• Control loop: PID + feed-forward, 25 Hz update, <40 ms control latency
• Sensors: Spreader IMU 6-DOF, trolley encoder 4096 ppr, load-cell 0–60 t ±0.5%
• Performance: Residual sway <1°, drop accuracy <±2 cm at 24 m cable length
• Bus: CAN J1939, EtherCAT, or Profinet to existing VFD
• Compliance: SIL-2 (IEC 61508), CE, ISO 13849-1 PL d
• Environmental: Controller IP65, −30 to +70°C, EMC EN 61000-6-4
• OEM compatibility: Konecranes, Kalmar, ZPMC, Liebherr, Mitsui, Doosan, Reggiane, Paceco
• Install time: Typical retrofit 3–5 days per crane during planned shutdown