MODULE M3 · 10.0 HOURS

Actuator and Controller Selection

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LEARNING OBJECTIVES

Module objectives

  1. Understand the rated voltage, current, and communication characteristics of DYNAMIXEL XM430-W350-T actuators.
  2. Master the DYNAMIXEL port configuration and 12V power isolation structure of the OpenCR 1.0 controller.
  3. Design voltage divider circuits using FSR 402 sensors and 10kΩ resistors.
  4. Calculate system power requirements and establish independent branch fuse protection designs.

Actuator and Controller System Design Theory

1. Actuator Selection and Power Characteristics

Use DYNAMIXEL XM430-W350-T for precision robotic hand actuation. This actuator operates at a nominal voltage of 12V, with a stall current of 2.3A [S11]. The complete robotic hand consists of 11 actuators, so the total stall current sum reaches approximately 25.3A. Therefore, an independent power supply system is required for stable operation.

2. Controller Architecture

OpenCR 1.0 is equipped with a 216MHz ARM Cortex-M7 processor, making it suitable for real-time control [S13]. This controller supports a structure that can physically separate the 12V actuator power from the logic/sensor power. Analog inputs such as FSR sensors must be processed within the 0~3.3V range, so the sensor voltage divider circuit must be powered by the OpenCR’s 3.3V sensor rail [S13].

3. Overcurrent Protection and Power Branch Design

Use 3 MEAN WELL GST160A12-R7B adapters with 138W output [S15]. The rated current for each adapter is 11.5A, which creates 3 independent 12V branches. Each branch is equipped with an in-line 10A ATOF fuse to protect the circuit in the event of an overcurrent [S24, S25]. The fuse is set lower than the rated current of 11.5A to achieve protection coordination.

4. Sensor Signal Acquisition

FSR 402 exhibits the characteristic that resistance decreases as pressure increases [S12]. Connect this to a 10kΩ fixed resistor and a voltage divider to convert the change in force into a voltage signal, and input it to the OpenCR 12bit ADC port [S12, S13, S26].

WORKED EXAMPLES

Worked examples

  1. Example 1: Verify maximum current per branch. When connecting 4 XM430 actuators to one branch, the sum of stall current is 4 * 2.3A = 9.2A. This satisfies the 11.5A rating of the adapter and the 10A rating of the in-line fuse, maintaining a safe range [S11, S15, S25].
  2. Example 2: Calculate FSR divider circuit voltage. Under 3.3V supply voltage, when FSR resistance is R_fsr, ADC input voltage V_adc = 3.3 * (10k / (10k + R_fsr)) V. Check resistance changes according to sensor range (0.2N~20N) and calibrate so as not to exceed the 0~3.3V range [S12, S13, S26].

LAB PROTOCOL

Power Branch Configuration and ADC Sensor Interface Practice

  1. 1

    Connect an 0AFH0001Z fuse holder to each MEAN WELL adapter output and insert an 0287010 10A fuse.

  2. 2

    Set the multimeter to DC voltage mode and verify that the voltage of each branch is a stable 12V.

  3. 3

    Configure a divider circuit using a 10kΩ resistor and FSR 402 on OpenCR's 3.3V sensor rail.

  4. 4

    Verify that the output voltage of the divider circuit is within the 0~3.3V range in a non-powered state.

Safety check
  • Physically disconnect the AC power of the 3 adapters before starting work and verify 0V using a multimeter.
  • Always wear impact-resistant work goggles.
  • Never modify circuits or touch wiring while power is applied.
  • Clearly state that fuses are for overcurrent cutoff and not for planned stops.

Lab deliverables

  • Records of 12V output measurements for each branch
  • Photos of assembled FSR divider circuit
  • Configured wiring diagrams

ASSIGNMENT

Power Branch and Protection Design Review

Deliverables

Rubric

  • Are independent fuses correctly placed in each branch?
  • Is the actuator branch distribution 4/4/3 in compliance with regulations?
  • Is sensor power supplied from the 3.3V sensor rail instead of 12V?

KNOWLEDGE CHECK

Knowledge check

1What is the correct power connection for a divider circuit using FSR 402 sensors and 10kΩ resistors?
2What is the stall current value of the XM430-W350-T actuator?
3What is the action strictly prohibited in power branch design?

FIELD CHECK

Completion criteria

  • Verification of 12V voltage of 3 independent branches completed via multimeter in lab
  • Completed wiring and ADC input voltage range verification of FSR 402 sensor divider circuit
  • Submission and passing of power branch and protection design report

MODULE SOURCES

Module sources

  1. DCX 10 L 10 mm, precious metal brushes, DC motor DCXmaxongroup.com · datasheet
  2. ESP32 Wi-Fi & Bluetooth SoC | Espressif Systemsespressif.com · datasheet
  3. XM430-W350 e-Manualemanual.robotis.com · datasheet
  4. OpenCR 1.0emanual.robotis.com · technical_documentation
  5. GST160A12-R7B Enclosed Desktop Power Adaptermeanwell.com · datasheet
  6. ATO AFH Series In-Line Fuse Holderlittelfuse.com · datasheet
  7. ATOF 287 Series 10 A Blade Fuselittelfuse.com · datasheet
  8. FSR Model 402interlinkelectronics.com · datasheet
  9. 10K Ohm 5 Percent 1/4W Through-Hole Resistorsadafruit.com · technical_documentation