Activities

Structural mechanisms

NANOPOSITIONING, SHAPE CONTROL AND ACTIVE DAMPING

From laboratory to space application, Micromega Dynamics offers high-precision mechanism concepts to meet client requirements.

Micromega Dynamics is your partner for the design of shape control force actuators, nano positoning system or isolation platform. Based on your specification (force, accuracy, power dissipation, allowed space…), we design and manufacture dedicated actuators based on proven actuator concepts. Our actuator can be driven in closed-loop based on internal (or external) sensors such as high accuracy force sensor (0.02%FS), proximity or vibration sensors. The local embedded control electronics running the innovative control laws (decentralized approach) and continously monitoring the actuator operation can also be used to communicate with our client controller or monitor through either a CAN network or a TCP/IP link.

We are able to design mechanisms that achieve a high level of integration of mechanics and electronics. Furthermore, by using rugged electronics and local control algorithms our mechatronic devices operate reliably in harsh environments. Performance analysis on prototypes is used to qualify our mechanisms before deploying the devices on site.

Examples of applications

1

MIRROR SHAPING
ACTUATORS

The resolution of astronomical telescopes usually depends on the primary mirror aperture (its diameter) but also on the quality of its surface finish, the defects of which lead to imaging errors. The defects are originated either during the manufacturing/ assembling process (polishing errors) or during the life of the telescope (gravity loading, thermo- mechanical stresses, wind, etc.).

In the past, thick mirrors were used to avoid these later defects. Nowadays, thinner and lighter mirrors are used in combination with special actuators applying very precise loads (0.02%FS) at the back of the mirror. Additionally, these actuators must also be very compliant in order to avoid parasitic loadings due to the relative motion between the mirror (made of glass) and the mirror cell (made of steel). Finally, the power dissipated by the actuator must be very low (<1W) in order to avoid local heat generation at the back of the mirror.

2

ACTIVE DAMPING INTERFACE

The Active Damping & Steering Interface consists of a stiff sixdegrees- of-freedom hexapod (Stewart platform with cubic architecture). Each leg consists of a linear piezoelectric actuator, a collocated force sensor and flexible tips for the connection to the base plates. The hexapod can be used as damping interface connecting arbitrary structures, a micro-vibration isolator and a high-precision pointing mechanism.

Optionally, the legs can be provided with strain or elongation sensors, so that the hexapod can be used as an interface with infinite stiffness at low frequency. The maximum axial stroke is 90 micrometers and the maximum tilt is 0.4mrad.

icon-active-damping

3

MAGNETIC BEARING FOR OPTICAL DELAY LINE

Optical Delay lines are used in advanced optical systems (e.g. aerospace applications). Here the objective is to make a high-resolution/ long-stroke positioning device for a synthetic aperture optic. The resolution is usually a nanometre or less while the stroke can be several tens of millimetres. Because they are mainly used in cryogenic environments, the total power dissipation is always in the range of the milliwatt or less. Magnetic bearings were designed to produce a smooth reliable frictionless movement and the positioning of the optical payload.

icon-magnetic-bearing