QUBE Servo 2 Teaching Experiment Platform

Open the example model that comes with QUARC (such as q_qube_position_comtrol. slx) and try compiling and running it. If the example is normal, it indicates that there is a problem with the user model; If the example also fails, reinstall QUARC.

Fault 3: Abnormal shaking or overcurrent during motor operation

Possible reasons:

Unstable control parameters (such as oscillation caused by excessive PID gain).

The encoder signal is affected by interference or mechanical coupling is loose.

The motor shaft is stuck (additional module not installed correctly).

Exclusion steps:

Immediately stop running and retest with a small proportional gain (e.g. Kp=0.1) to observe if the position response is stable.

Use QUARC's "Monitor&Tune" tool to view the encoder count values in real-time and confirm that the values continuously change without any jumps when manually rotating the motor shaft.

Check if the inertia disk or swing rod is locked. The quick connect interface should make a "click" sound.

If all of the above are normal but still shaking, please use a current sensor to read the actual current and determine whether it is caused by wear of the internal commutator of the motor or short circuit of the brush.

Fault 4: Embedded version SPI communication is unresponsive

Possible reasons:

SPI pin connection error (incorrect MOSI/MISO/SCK/CS correspondence).

The clock polarity and phase settings do not meet the requirements of QFLEX 2.

The SPI rate of the microcontroller is too high (QFLEX 2 supports up to 2 MHz).

Exclusion steps:

Strictly refer to the interface data manual provided by Quanser and check the wiring: usually CS → D10 (Arduino), SCK → D13, MOSI → D11, MISO → D12, power supply and GND are correctly connected.

Set SPI mode to mode 0 (CPOL=0, CPHA=0), with MSB transmitting first and clock speed set between 500 kHz and 1 MHz.

Use a logic analyzer or oscilloscope to monitor the SPI bus and confirm that QUBE has response data after each command byte.

It is recommended to run the Arduino sample code provided by Quanser first, confirm that the hardware is working properly, and then develop a custom program.

Modular Expansion and 3D Printing Interaction

A prominent feature of QUBE Servo 2 is its support for users to design and 3D print additional modules on their own. The original factory provides inertia discs and swing rods, but teachers can encourage students to design other loads, such as:

Eccentric mass block: Simulate unbalanced loads and test anti-interference ability.

Spring damping load: Printing specific shapes using flexible materials to generate nonlinear friction or elastic torque.

Fan blades: used for air resistance experiments to study the damping effect of velocity squared.

Technical interface specifications (based on implicit information in the original text):

The quick connect interface adopts a magnetic or snap on structure, with an outer diameter of about 15 mm and a D-shaped shaft hole in the center to match the motor shaft.

The maximum allowable mass of the module is approximately 50 g (exceeding it may affect the lifespan of the motor).

The recommended range of rotational inertia for the module is approximately 1 × 10 ⁻⁵ kg · m ² for the inertia disk and 2 × 10 ⁻⁵ kg · m ² for the swing rod.

Engineering suggestion: When designing new modules, CAD software should be used to ensure dynamic balance; Recommended printing materials are PLA or ABS, and it is not recommended to use metal (heavy). In student projects, they can be required to:

Design a novel load.

Measure its rotational inertia and friction model through system identification experiments.

Redesign the controller for this load and compare the performance differences.

Align teaching course resources with ABET

For USB version users, Quanser provides a complete set of digital media course resources, whose core value lies in:

Modular content: Teachers can choose experiments as needed instead of writing experiment guides from scratch. The content covers: system modeling (first-order, second-order), time-domain response, PID control, frequency response, state space control, digital control, etc.

Textbook Alignment Tool: Provides a mapping table that corresponds each course section to a chapter in mainstream textbooks such as Nise's "Control Systems Engineering" and Ogata's "Modern Control Engineering". This greatly reduces teachers' preparation time.

ABET certification support: Course resources clearly indicate the student learning outcomes covered by each experiment (such as "being able to design controllers that meet steady-state error and overshoot requirements"), which helps in writing certification reports.

Embedded version resources: Provide Arduino examples and interface data manuals. Although there is no complete ABET alignment course package, teachers can draw on the content framework of the USB version and let students write their own controller C code to achieve the same function, which is very valuable for cultivating embedded engineers.

Maintenance and calibration recommendations

Although QUBE Servo 2 is designed to be maintenance free, the following issues may still occur after long-term use: