micro Harmonic Drive® as an Eccentric Actuator
Eccentric actuators shine by virtue of their simple system structure and high precision. The combination of a micro Harmonic Drive® gear and a zero backlash eccentric mechanism can be used to implement extremely light-weight, space-saving positioning systems for highly precise adjustment procedures in the sub-µm range.
Small, light, versatile
Depending on the performance spectrum, outer diameters lie between 8 and 10 mm. Because of their small outer dimensions and exceptionally low weight (less than 10 grams), these systems can very readily be integrated into highly dynamic processes. These eccentric actuators can be configured with either a stepper motor or a servo motor. This allows them to be adapted to the customer's control environment and process management without compromise. Zero backlash is realised by the eccentric's preloaded ball bearing.
Optional gear reduction ratios
Depending on required resolution or actuating speed, eccentric actuators are produced with different gear reduction ratios. As an illustration, the achievable resolution of a step increment is 0.15 µm using a stepper motor operating in half-step mode and an eccentric of 1 mm with a gear reduction ratio of i = 1000. Resolution is even smaller, at 0.02 µm, for a servo drive with encoder (256 pulses per revolution) and a gear reduction ratio of i = 1000. The potential actuator travel for this example is 2 mm.
The low component count for motion conversion minimises failure rates and ensures high quality positioning characteristics — including excellent repeatability. These systems are superior to actuators based on piezoelectric technology in many applications. This is because of their simple, robust structure and ease of simple to control offer greater stability under production conditions. They can be optimally integrated into very harsh environmental conditions, such as ultra high vacuum.