A major global company in private space-travel and exploration was looking for a solution to control their tandem overhead cranes. These tandem cranes are used for final rocket assembly and operate at a height of more than 100 meters. This highly specialized application requires precise real-time measurement and a constant feedback loop between the cranes and the operator on the ground.
The system consists of two cranes, with a single trolley, working in tandem. The load weight is measured by four separate compression loadcells located at the four corners of the trolley. One central i-C4C on the crane adds up the four values to calculate the total load on the crane, which is displayed on a 300 mm 5-digit display connected through Wi-Fi and mounted on the crane, visible to operators.
A second i-C4C on each crane, connected to the first through CAN bus, is equipped with RF communication and responsible for communication and tandem functionality between the cranes. They also aggregate the load of both cranes to protect the runway from overloading.
The cranes are controlled by two IK3 Danfoss joystick transmitters, provided and built by our sister company Indic BV. Either of the two transmitters can control both cranes at once if necessary.
Each crane has two receivers. The first is for movement control through relays. Some of the movements, such as lifting, are also monitored by the i-C4Cs to protect against overload. The second receiver is connected to the same CAN bus as the two i-C4Cs on the crane. It reads important data from the i-C4Cs, such as the weight on every loadcell, the aggregated loads, and possible alarms. Through a separate channel, this information is sent back to the transmitter, where it is displayed on a screen. The two receivers are used to ensure a constant transmission and feedback line – a set-up known as “full-duplex”.
All the parameters are also transferred to a separate visualization platform where key statistics can be consulted such as the average load and the number of overloads per month.