Using the Joystick Interface for Analog Signal Control of the E-873 Piezo Stick-Slip Motor Controller

The E-873 piezo stick-slip motor controller supports analog input, but it does not provide direct analog position control comparable to that of a classical piezo-stack nanopositioning system. In a piezo-stack-based stage, the applied control voltage is amplified with a fixed gain and directly drives actuator expansion, so voltage corresponds directly to target position. In contrast, the E-873 reads the analog input signal and processes it through the digital PIMikroMove interface, which then determines and commands the resulting motion.

For a specific customer application, this software-based method did not provide sufficient response speed and was considered too slow and inefficient.  The note here describes a more direct analog input path.

While the standard analog I/O interface was not suitable to achieve this goal, the joystick input of the E-873 provided a practical alternative. This input accepts an analog signal in the range of 0 to 3.3 V and can be configured through the PIMikroMove application.

To interface the external signal source with the controller, a custom cable was fabricated using:

• a 6-pin mini-DIN male connector for the controller side
• a BNC connector for the signal source side

This configuration allowed the analog output of a function generator to be connected directly to the joystick input of the E-873.

This method does not convert the E-873 into a true analog-position servo controller. Rather, it provides an alternative analog command path using the joystick interface when the standard analog input method is not fast enough for the application.

Performance will depend on signal quality, controller configuration, and the behavior of the connected stage. Care should also be taken to ensure that the input voltage remains within the specified 0 to 3.3 V range of the joystick port.

Triangular Waveforms