Precision Motion
Tripods / Hexapod Precision Positioning Systems
Parallel-kinematic piezo positioning platforms for applications requiring high stiffness, compact geometry, programmable pivot points, and precision motion in magnetic-field-sensitive environments.
What Tripods Are Used for in Precision Motion Control, and How They Differ from Hexapods
Tripods are parallel-kinematic positioning systems that use three coordinated actuators to generate controlled motion in three degrees of freedom. Depending on the mechanical layout, a tripod can provide Z, tip and tilt motion, or a combination such as X, Z and rotation about the Y axis. This makes tripod stages useful for precision alignment tasks where a component, optic, sensor, sample, or fixture must be translated and tilted around a defined pivot point without the size and complexity of a full 6-axis system.
In precision motion control, tripods are used for optical alignment, beam steering, wafer and sensor positioning, metrology setups, goniometer-style positioning, and applications where a large clear aperture or low profile is important. Their parallel-kinematic design keeps the moving mass low, improves stiffness, and avoids the error buildup common in stacked serial stages.
The key difference from a hexapod is the number of controlled degrees of freedom. A hexapod uses six actuators to provide full 6-DOF motion: X, Y, Z, pitch, yaw, and roll. A tripod is simpler and typically controls three degrees of freedom. Choose a tripod when the task requires precise lift, tilt, or planar positioning with fewer axes; choose a hexapod when complete spatial alignment and programmable 6-axis motion are required.
Piezo-actuated tripod fast steering mirror concept.
Piezo Tripod Z-Tip/Tilt Platform Concept
A large Z-tip/tilt nanopositioning platform was developed using closed-loop PiezoWalk drives and position sensors.
Preliminary Specifications
- Z, tip, tilt platform with closed-loop drives and position sensors
- Diameter: 300 mm / 12"
- Load capacity: 200 N
- Travel range: 1.3 mm
- Tilting angle: 10 mrad
- High-resolution incremental sensor
Piezo tripod Z-tip/tilt stage platform concept with central aperture.
Piezo Hexapod Concept
A custom, non-magnetic piezoelectric hexapod based on ultra-precision piezo motor drives was also developed. This 6-axis precision positioning system can be used in applications with very strong magnetic fields.
Preliminary Specifications
- 8" aperture
- 50 kg load
- Low profile: 140 mm
- XYZ translation: 10 mm
- Rotation around all axes: 6°
Stylized piezo hexapod concept with central aperture and parallel-kinematic actuator layout.
Parallel-Kinematics Tripod Micropositioners
In addition to 6-axis hexapods 3-axis stages can also be based on parallel kinematics design principles. An innovative X, Z, θY tripod low-profile Z θZ θY stage is available.
3-Axis Precision Positioning Systems
A variety of 3-axis stages for precision positioning is available
Concept: Parallel-Kinematic Tripod / Goniometer
A parallel-kinematics tripod concept was designed for precision positioning in X, Z, and θY, offering elevation, translation, and tilt motion around the horizontal Y axis with a user-defined pivot point.
- Goniometer Z stage with freely selectable pivot point
- Travel ranges: 50 mm / 50 mm / 30deg
- Load capacity to 4 kg
- Minimum incremental motion to 100nm
- Compact parallel-kinematic design