Sunly launched its new‑generation curved‑rail stacker crane system early this year, adopting a complete SEW drive‑and‑control solution. This also marks the first domestic application case of SEW’s curved‑rail stacker crane system in China.
Guangdong Sunly Intelligent Logistics Equipment Co., Ltd. is a system integrator and manufacturer providing overall intelligent‑logistics solutions. Its products and services cover logistics information system development, automated high‑bay warehouses (stacker cranes, conveyors, elevators, etc.), AGV mobile robots, warehousing racks, supply‑chain management and supporting services. Endowed with strong technical strength and product‑development capabilities, the company has independently developed multiple high‑performance stacker cranes to meet users’ demands for higher lifting height, faster speed and stronger performance within limited space compared with conventional solutions.
Sunly rolled out its brand‑new curved‑rail stacker crane system early this year, equipped with a full‑set SEW drive‑and‑control solution — the first domestic deployment of SEW’s curved‑rail stacker‑crane system. The technology enables precise positioning at arbitrary positions across multiple aisles, delivering smooth transit through curves with high speed and efficiency. It is suitable for automated high‑bay warehouses with numerous aisles and high‑reliability requirements, helping reduce the quantity of stacker cranes and cut overall costs.
Featuring a flexible modular product portfolio and pre‑defined stacker‑crane software modules, the complete SEW drive‑and‑control solution greatly facilitates Sunly’s stacker‑crane design and commissioning. Among them, SEW’s pre‑defined stacker‑crane software module MOVIKIT®CurveDrive is tailor‑made for curved‑rail stacker cranes and integrates multiple dedicated application functions. Its key capabilities are highlighted below:
I. No restrictions on external encoder selection; automatic encoder‑position‑source switching
On curved tracks, the middle section of the stacker crane moves away from the rail. Conventional curved‑rail stacker‑crane solutions must mount reading heads on the crane’s head section to read barcodes, relying solely on barcodes for distance measurement. The SEW MOVIKIT®CurveDrive software module automatically switches the positioning source from external encoders (e.g. laser rangefinders, barcodes) to motor encoders before entering a curve, and switches back to external encoders after exiting the curve. This function lowers mechanical‑design difficulty and imposes no restrictions on external‑encoder types.
II. Automatic differential‑speed and load‑distribution control for two drive wheels for enhanced dynamic performance and reduced mechanical wear
Curved‑rail stacker cranes adopt dual‑wheel drive. Traditional solutions commonly use master‑slave control, where the slave motor follows the master motor’s current or speed. Time lags in master‑slave motor responses cause counter‑torque conflicts, inevitably leading to mechanical wear and poor dynamic performance. Breaking the master‑slave architecture, MOVIKIT®CurveDrive treats both drives as equal entities and eliminates dead zones caused by master‑slave start‑response delays for superior dynamics. MOVIKIT®CurveDrive controls dual‑wheel drive via three functions:
Load Distribution
When load is unevenly distributed between drive wheels, the software module dynamically balances loads across both drive wheels, enabling higher acceleration and shorter operating cycles for the stacker crane.
Anti‑Slip Control
Dirt or oil stains on rails may cause drive‑wheel slip, which can trigger system shutdown or even damage drive wheels and rails. Anti‑slip control automatically detects drive‑wheel slip, limits slip deviation to parameter‑defined thresholds and sends warning messages to the higher‑level controller. It prevents mechanical damage caused by wheel‑runaway and improves overall system reliability.
Electronic Differential
When negotiating curves, the software module automatically calculates and adjusts differential speeds for the two drive wheels according to curve radius and wheel positions to maintain constant stacker‑crane travel speed.
Implementing these functions via upper‑level PLC programming brings challenges including complicated programming, communication latency, low positioning accuracy, difficult commissioning and cumbersome maintenance. MOVIKIT®CurveDrive automatically identifies curve segments, calculates wheel speeds and load distribution, and enforces differential‑speed limits. Users only need to input mechanical parameters (e.g. turning radius, rear‑wheel track width). It reduces upper‑level PLC programming workload while simplifying commissioning and maintenance.
III. Automatic positioning to any position across multiple aisles with simplified upper‑level PLC control
MOVIKIT®CurveDrive automatically identifies the target aisle and required switch points. Given valid switch‑point status from the upper‑level PLC, the stacker crane passes through curves autonomously. If switch points are misaligned, the crane automatically travels to a waiting position ahead of the switch. For upper‑level PLCs, multi‑aisle warehouses can adopt the same control logic as single‑aisle warehouses. Positioning across multiple aisles is accomplished simply by sending target positions, travel speeds and switch‑point status signals.
IV. Real‑time speed monitoring during positioning deceleration with software‑enabled runaway prevention
This function monitors speed during deceleration under positioning mode. Pre‑defined tolerance bands are set for deceleration ramps. Parameter IrTargetOffset defines the monitoring line along the X‑axis travel direction, while lrRampVelocityGradient sets the allowable gradient of the monitoring ramp: values greater than 1 produce a steeper monitoring ramp; values less than 1 yield a gentler ramp. If speed exceeds permitted limits during deceleration, an error message with a corresponding error‑ID is reported to the upper‑level PLC.
V. Graphical parameter‑based configuration to shorten commissioning time
Like other SEW pre‑defined software modules, MOVIKIT®CurveDrive adopts graphical parameter‑oriented configuration instead of complex free‑form programming for fast commissioning. Its intuitive graphical editing interface and diagnostic interfaces cut initial commissioning and startup time by up to 80 %.
As a leading enterprise in power transmission, SEW keeps abreast of industry developments and technical demands for automated high‑bay warehouses, and is committed to delivering custom‑built, stable and energy‑efficient system solutions widely deployed in intelligent warehousing across diverse industries. The curved‑rail stacker‑crane solution enables Sunly’s stacker cranes to operate more efficiently, stably and reliably on‑site, earning high recognition from customers.
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