DSM developed a fully nonmagnetic 3-axis high-travel/high accuracy rotational positioning system for use inside a 3-axis Helmholtz coil. This goniometer is capable of 180 degrees of rotation around the X and Y axes and 360 degrees of rotation around the Z axis. Each axis is equipped with a high resolution encoder capable of determining the angle of the axis down to better than 8 millidegrees (or 140 µrad). Fully nonmagnetic piezoelectric motors are directly coupled to each axis, providing true zero backlash. Cable chains are used to route all motor control and feedback signals throughout the stage system. Two power/signal lines run through the cable system to connect power and communication signals to the "device under test".The goniometer stage positioned the "device under test" at any point inside its range of motion, where it could be operated in a predetermined orientation inside a specified magnetic field. The controller was located outside the system. The self-locking nature of the piezoelectric motors meant that, once in position, the stage could effectively be powered off without moving. When not moving, the stage only required power to the encoders to maintain current stage positioning. The stage was constructed with absolutely no magnetic materials (including no stainless steel fasteners) and generated virtually no magnetic fields due to its ultra-low standby power draw.The video below shows the stage demonstrating some of its high range of motion, servoing to each position and holding in its low power state before transitioning to the next one.
