Hexapods / Stewart Platforms for Astronomy
Commercial Stewart-Gough platform and parallel-kinematic hexapod systems for telescope alignment, active optics, image stabilization, radio telescope instrumentation, and precision observatory applications.
Resolution in large earthbound telescopes is limited by atmospheric turbulence and vibrations. During the last 2 decades PI has designed many large-aperture high-speed tip/tilt systems and hexapod alignment systems for image stabilization and alignment. Piezoelectrically-driven active secondary mirrors can improve the effective resolution up to 1000% by correcting for these image shifts in real time, especially during long integrations with weak light sources.
More information on fast steering mirrors, hexapods and other precision motion products for Astronomy.
PI's hexapod 6-axis micropositioning systems are key components for the precise alignment of active mirrors.
PI precision actuators provide superior performance and lifetime and have been used in large telescopes such as the ALMA Telescope in Chile consisting of 60+ Antennas spread across distances of up to 16 kilometers.
PI is the leading manufacturer of Hexapod high-performance micro- and nanopositioning systems. These parallel-kinematics devices, in a number of different forms, are suitable for diverse applications, ranging from handling systems in electronics fabrication and tool control in precision machining, through medical technology, to optical systems like those found in space telescopes and satellite receiving antennas.
Various models of the powerful parallel kinematic machines (PKM) can move masses of 50, 200 or even 1000 kilograms with micron accuracy as required in their respective applications.
These Hexapod systems are all built with six, high-resolution electro-mechanical or piezoelectric actuators connected to a common platform, similar to flight simulators, yet considerably more precise: in place of hydraulic cylinders, the Hexapods are driven by highly accurate, precision-controlled rotary or linear motors. Different drive principles are employed, depending on the application: Hexapods with piezomotor drives make for a positioning system which is not only vacuum compatible but also completely non-magnetic.
Compact 6-Axis Motion
Hexapods provide X, Y, Z, pitch, roll, and yaw motion from one compact mechanism instead of a stack of individual linear and rotary stages.
High Stiffness
The payload is supported by six parallel struts, helping provide stiffness and stability for optics, mirrors, sensors, and telescope instrumentation.
Reduced Moving Mass
A common moving platform reduces the cumulative moving mass associated with serial stage stacks, improving dynamic behavior and settling.
| Requirement | Why It Matters in Astronomy | Hexapod Advantage |
|---|---|---|
| Mirror Alignment | Secondary mirrors and active optics require precise angular and linear adjustment. | Software-controlled six-axis alignment with a virtual pivot point. |
| Image Stabilization | Atmospheric turbulence and vibration can shift images during observation. | Fast tip/tilt and multi-axis correction can improve effective imaging performance. |
| Large Payloads | Observatory components can be heavy and difficult to align manually. | Parallel-kinematic designs can position high loads with micron-level precision. |
| Vacuum / Non-Magnetic Needs | Space instrumentation and special scientific systems may require low outgassing or non-magnetic operation. | Vacuum-compatible and piezomotor-based non-magnetic hexapod designs are available. |
Active Mirror Positioning
- Secondary mirror alignment
- Tip/tilt image stabilization
- Active optics correction
Radio Telescope Systems
- Reflector positioning
- Antenna alignment
- Sub-micrometer adjustment under harsh conditions
Scientific Instrumentation
- Spectrograph alignment
- Sensor positioning
- Space telescope and satellite receiving antenna systems
All PI Hexapod systems include a sophisticated, yet easy to use motion controller. The Hexapod controller allows the user to set a pivot point anywhere inside or outside the Hexapod working space, by a simple software command. This randomized pivot point stays with the platform, no matter how it moves—an invaluable feature for example in optics applications. Moves are specified in Cartesian coordinates and the PC-based controller transforms them into the required motion-vectors for the individual actuator drives. The latest controller generation features flexible interfaces: TCP/IP, for remote / network / Internet addressing or highspeed RS-232.
Learn more about PI hexapods, parallel kinematics, miniature hexapods, high-load hexapods, vacuum-compatible hexapods, and hexapod control software.
Standard HexapodsMiniature HexapodsVacuum HexapodsHigh-Load Hexapods