Riding comfort in rollercoasters

On many rollercoasters, speed and acceleration are of primary importance, but riding comfort is also decisive for themed rollercoasters in which impressions are left both by the ride and the opportunity to experience the environment. This is especially the case when extremely young passengers are being addressed. For the “Arthur and the Minimoys” ride in Europa-Park Rust, intelligent converters for e-motors by Sensor-Technik Wiedemann (STW) in combination with a sophisticated control unit provide unsurpassed riding comfort. EMIS Electrics GmbH assumed responsibility for the integration of this complex control technology.

The family-run company Mack not only manufactured this system under the name MACK Rides, but also acts as the operator of Europa-Park Rust. This constellation enables the company to develop innovative and optimum solutions for their customers, based on their wide practical experience. With the design and development of the steel rollercoaster for the “Arthur and the Minimoys” themed area, the focus was placed on the riding comfort in this “Inverted Powered Coaster” driven by e-motors. “Inverted” means that the trains hang under the rails, and “powered” describes the fact that the trains have their own drive system. In addition, MACK Rides also enable their “Powered Coasters” to run freely on downward sections.

Each of the eight “Arthur” trains has four independent e-motors equipped with converters. The drive systems are indirectly coupled with one another without a rigid connection via transmissions in order to undertake dynamic adjustments via a control unit. In case of pure speed control, the drive systems would work against one another due to differing diameters in the drive line (e.g. worn drive wheels, manufacturing tolerances) or due to tolerances in the speed measurement, which is carried out via a resolver. Smaller wheels want to increase the speed, and larger wheels want to reduce the speed. On curves, the outer wheels operate at greater speed, and therefore a pure speed control is not practicable. Torque control alone is also impractical, as the drive systems could slip if there is no load. In addition, problems such as insufficient contact pressure (curves) or icing of the rails in the outer area may result.

Indirect load compensation regulation could address this problem and be implemented in the control centre control unit. However, this central version cannot be utilised due to the latency periods occurring in communication. The solution is therefore the direct load compensation control by means of ESX control components by STW, freely programmable in “C” and integrated into the converters. This type of regulation ensures torque equality in all drive systems.

Close and constructive cooperation between the companies STW and EMIS was required here for the technical implementation. During this joint development, an intelligent load compensation control was created. The result was a reduction of the occurring torque ripple to a quarter of the value of the indirect control , which has a direct effect on the riding comfort and associated riding experience.

Temperature monitoring by means of PT1000 elements has been integrated into each e-motor, which is activated in case of overheating and reduces the load. Furthermore, certain error reactions have been defined within the ESX-control components, so that the control centre no longer has to concern itself with these issues. Each slave can also take over the master role through simple re-configuration, so that each train can be safely traversed back at any time.

In parallel, all CAN messages exchanged between the master and slaves are recorded on a TC3G, the telemetry product by STW. The TC3G acts as a gateway and transfers the data to the control centre. As a result, the functionality of the control circuit is checked and error incidents are documented and analysed by means of MatLab/Simulink. In the opposite direction, the ESX control components can be re-configured or programmed. Last but not least, the system reveals yet another positive effect which has been achieved through the use of the converters by STW: The “Arthur and the Minimoys” dynamic rollercoaster is the first system which can recuperate and feed energy back into the network when braking.