Background
WFT’s robot-based MIT modular transport technology enables large, heavy loads to be moved in any direction and positioned precisely where they are needed. Optional features allow each order to be tailored to customers’ needs, reducing downtime, improving quality and increasing efficiency. WFT’s Modular Individual Transport System (M.I.T. WFT) enables unrestricted mobility for heavy vehicles that can carry loads of up to 500 tons. The M.I.T. WFT system moves loads at very low heights, with a maximum vehicle height of 320 mm. The vehicle is designed to easily overcome common obstacles, like factory hall entrance sills. Each system is equipped with a minimum of four pairs of wheels, two wheels at each corner.
Read this case study to learn about:
- How to achieve high current for extended periods, ideal for autonomous guided vehicles and battery powered applications
- Reducing power dissipation and increasing duty cycle between battery recharges, with highly efficient Elmo Gold Drum drives
- Achieving both smooth and accurate movement with small, high-power-density density drives
- Fast and accurate tuning using Elmo EASII software
Machine Requirements
The WFT M.I.T. requires eight servo drives supplying high current for periods as long as several minutes. Since each wheel is equipped with a servo motor, WFT needed a controller that would synchronize all axes in real time with high precision. The servo drives needed to provide smooth motion when carrying sensitive heavy loads and to sustain the highest levels of current for extended periods. With this, the motion control solution needed to be tailored to the limited space available in the vehicle, and it needed to easily interface with the existing PLC via CANopen.
Motion Control Solution
- 8 Gold Drum 70/60 SE servo drives for wheel sets supporting up to 8 tons
- 8 Gold Drum R150/100SE servo drives for wheel sets supporting up to 25 tons
- The Elmo Studio Application Studio (EASII) for fast, easy servo drive setup
Elmo’s Gold Drum servo drive was chosen for the next generation M.I.T. WFT transport vehicle because it solved all the key technical challenges and offered significant performance improvements. Elmo’s solution also met WFT’s requirement that it work with legacy equipment, use open protocols (CANopen), and enable upgrading of the vehicle within a few days.
Elmo’s Gold Drum provides smooth, precise velocities, jitter-free motion and no tracking errors. Elmo’s ‘R’ type drives provide sustained high current for extended periods regardless of loads, enabling 360° wheel movement. Elmo supplied the off-the-shelf servo drives and components to WFT, and provided extensive support to WFT’s engineers, enabling a rapid and efficient upgrade within two working days.
In addition to the advanced precision and smooth servo performance, high current, small size, WFT also gained a very green product. Elmo’s proprietary “FASST Power Conversion” Technology results in the lowest heat dissipation, which in addition to prolonging battery operating time and extending battery life, reduces heat and EMI to negligible levels.
As a result of the high efficiency and high-quality power dissipation, temperature rise is very slow and fully controlled. The Gold Drum R150/100 SE can maintain 150 A consumption for 500 seconds with an average current consumption of 100 A – 120 A.
Results
Elmo’s solution was confirmed to be an ideal match for the M.I.T. WFT transport vehicle, providing a compact servo drive that met high current and resolution requirements with maximized system performance.
“When we learned that Elmo could provide us with the most accurate and powerful servo drive, and that it would fit into the tight dimensions of our M.I.T, we were pleased to try it out,” said Franz Wittich, CEO, WFT. “Elmo not only had the right solution, they also worked closely with us to install it – with Elmo’s engineering support, we had a working vehicle in only two days.”
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