Active vibration control for planetary gearboxes

Active vibration control at the test rig

In mobile high power applications such as car transmissions or aircraft engines, planetary gearing is preferred. In comparison to a parallel axis arrangement, it offers a higher power density. However, even with the benefits of the planetary gearing several difficult trade-offs have to be made. Primary goals are efficiency and weight but noise may not exceed a certain level. The designer can address both efficiency and noise for example by applying tooth flank corrections to the gears. However, the optimal solutions for the respective goals do not necessarily agree.

The introduction of active vibration control has the potential to overcome the drawbacks of existing solutions. Active vibration control can lead to quieter vehicles or machines. In addition, it can lead to a more efficient design because it frees the designer from prioritizing noise concerns. Active vibration control requires a precise knowledge of the characteristics of the vibration to be controlled. The vibration of planetary gearboxes is highly modulated. This is due to the motion of the planet gears.

The IMS has built a modular test rig for active vibration control for planetary gearboxes. It can operate different gearboxes at precisely controlled operating conditions. Several instrumentation options such as load cells, accelerometers and microphones may be configured. The test rig supports multiple inertial mass actuator at arbitrary locations. A high performance real-time computer may run novel control algorithms. The drawback of state of the art algorithms such as FxLMS is their reliance on accurate models of the transmission path of the vibration. However, changes in the system may lead to inaccurate models and to failure of model-based algorithms. The current research therefore focusses on model-free algorithms.