Gain Calibration— By calibrating gains for many different move sizes and adjusting the command  software to generate such commands on a per move basis PLADD could improve many performance parameters such as response time, overshoot, lag, etc.  Lessons Learned  1.Nanometers are really, really small.  When working in small numbers it is easy to forget how small nanometers truly are. In real life mechanical terms a nanometer is approximately 1/50,000 of the diameter of a human hair. When dealing with numbers of this size, deflections of mechanical components can play a large role in performance. Movements may not be actual position changes, like one is familiar with, but instead a “wind up” or deflection of the mechanical components in the drive-train. A well-designed system should minimize these effects. The remaining system deflections can be actively eliminated by employing an encoder in a  location such that it measures the output of the actuator that one is interested in controlling. Also, environmental noises, especially when not in a “quite” building may completely overwhelm any experimental results  2.Nanometer incremental step size is achievable with no gears, levers, or hydraulic reducers.  This one speaks for itself. It also was something I never expected possible.  3.Sensor technology is the limiting factor for fine positioning when proper mechanical design  considerations are taken.  Sensor technology is a fast growing field. As the sensor technology progresses one should not hesitate to  take advantage of technology. This especially applies to space-flight applications where a fear of the unknown can often be crippling, especially when attempting to actuate mechanisms with finer resolutions and more precision.  4.A clear path for oil circulation/pumping shall be designed into the system to avoid excessive  driving loads.  In designing our actuator a clear path for the oil to pass was not considered. Upon complete assembly  and operation it was discovered that much of our reserve torque was required to force the oil lubricant through the motor, screw, nut, bearing assembly. This leads to a reduced maximum velocity and an increased input of heat into to the actuator under continuous operation.  5.Full alignment adjustability makes everyone’s job easier. Access to the sensor without  disassembly is vital to technician (or assembling engineers’) sanity.  The actuator’s design requires that the sensor is housed inside a carbon fiber tube. The sensor cannot be  tested for functionality or alignment until the actuator is assembled. There is also no way to easily adjust the sensor once it is determined it is not aligned properly (inevitable, as it is practically impossible to blind assemble the sensor in perfect alignment). This requires that the actuator be slightly disassembled, shims guessed on based on previous experience and the whole procedure repeated. This can be extremely frustrating and time consuming. This problem may be eliminated as sensor technology improves and alignment tolerances grow. However, until then be sure to design in alignment adjustability and allow for active alignment post-assembly.  6.Instrument thin section bearing should be used with caution as they are extremely easy to  damage. We ran into a few issues with the handling of the thin section bearings during disassembly of the  actuators. More than one bearing was lost as a result of improper handling by technicians. Take caution with your technician choice and your handling procedures.    7.Obtain external mechanical noise measurements to isolate electronics noise and environment  noise. If external sensors are not used to measure the mechanical environmental noise it is impossible to  troubleshoot noise issues between the mechanical and electrical systems. The use of a local mechanical  385