Custom Electronics

Custom Electronics – definition

Custom Electronics in mobile robotics means electronic hardware designed or modified for a specific robot, payload, sensor stack, power architecture, or field environment. In practice, this usually includes custom printed circuit boards, carrier boards, interface modules, power distribution boards, protection circuits, signal conditioning stages, and embedded controller subsystems. The goal is not general-purpose automation. The goal is reliable integration of computation, sensing, actuation, and communication on a given UGV platform.

In the context of ROS 2 and UGV development, Custom Electronics sits below the software stack but directly affects software reliability. A ROS 2 node can only publish valid data if the underlying electronics provide stable power, correct voltage levels, synchronized timing, low-noise sensor interfaces, and deterministic communication links. This is especially important for fused navigation systems that combine LiDAR, IMU, wheel odometry, cameras, and GNSS. A hardware fault at the electrical level often appears in ROS as dropped topics, bad timestamps, encoder drift, USB disconnects, or unstable TF trees.

For Fictionlab platforms, the term is best understood as hardware adaptation around Leo Rover or Raph Rover. Leo Rover is a compact differential-drive platform with a Raspberry Pi-based compute unit and ROS support. It often needs expansion electronics for research payloads, sensor power rails, serial buses, CAN nodes, or safe battery integration. Raph Rover addresses higher payload and harsher field conditions, so custom electronics there often focus on power distribution, connectorization, EMI resilience, thermal margins, and support for heavier sensing or edge compute modules.

What custom electronics includes on a UGV

On a mobile robot, electronics is usually split into compute, motor control, sensing, communication, and power. A custom design can affect one or all of these blocks. The exact scope depends on whether the robot is used in a lab, outdoors, or in a research prototype with non-standard sensors.

Typical elements of custom electronics on a UGV include:

power distribution boards with fused rails such as 5 V, 12 V, and battery voltage
DC-DC converters sized for compute peaks, motor transients, and sensor startup current
microcontroller-based I/O boards for encoders, GPIO, PWM, ADC, and watchdog logic
interface boards for UART, RS-232, RS-485, CAN, USB, Ethernet, or camera interfaces such as MIPI CSI
sensor synchronization circuits using trigger lines, PPS input, or timestamp capture
protection functions such as reverse polarity, overcurrent, TVS diodes, and ESD protection
carrier or adapter boards for Jetson, Raspberry Pi, or custom compute modules
environment-specific connector systems and sealed harnesses

In ROS terms, these hardware blocks usually terminate in one or more drivers that publish standard messages such as sensor_msgs/Imu, sensor_msgs/LaserScan, sensor_msgs/Image, nav_msgs/Odometry, or sensor_msgs/BatteryState. If the electronics layer is poor, the message layer becomes unreliable even when the ROS graph is correct.

Why custom electronics matters in ROS 2 systems

ROS 2 standardizes communication at the middleware and message level, but it does not standardize electrical integration. That part is left to the robot builder. This is why custom electronics is often the difference between a demonstrator and a repeatable robotics platform.

Several ROS and ROS 2 conventions depend indirectly on hardware quality:

REP 103 defines standard units and coordinate conventions used by sensor and motion data
REP 105 defines coordinate frames such as base_link, odom, and map
sensor timestamps must be consistent enough for TF, state estimation, and sensor fusion
controller loops depend on stable bus latency and accurate encoder acquisition

If an IMU is powered from a noisy rail, bias stability may degrade. If a USB camera shares an unstable hub with a depth sensor, frame drops may rise. If GNSS and compute do not share time alignment, fused localization quality drops. These are electronics problems before they become software problems.

Key parameters and engineering metrics

Custom electronics should be specified with measurable parameters. This is necessary for verification and for later ROS integration. The exact values depend on the selected sensors and compute module, but the categories are stable.

Parameter	Why it matters	Typical engineering concern
Input voltage range	Battery compatibility	Undervoltage during motor acceleration
Rail current capacity	Peak load support	Compute and sensor inrush current
Ripple and noise	IMU, GNSS, camera stability	Switching converter noise coupling
Bus bandwidth	Sensor throughput	USB saturation, CAN arbitration, UART bottlenecks
Timestamp accuracy	Sensor fusion	Clock drift, unsynchronized MCU and SBC clocks
EMI and ESD robustness	Field reliability	Long cable runs, motor noise, outdoor handling
Ingress protection	Outdoor deployment	Dust, splash, connector sealing
Thermal envelope	Continuous operation	Jetson throttling, regulator derating

A simple power budget is often the first check:

P_total = Σ(V_i × I_i)
I_battery ≈ P_total / (V_battery × η)

Where η is converter efficiency. This estimate must include startup peaks, not only nominal load.

Integration examples for Leo Rover and Raph Rover

On Leo Rover, custom electronics is commonly used to extend the Raspberry Pi-based core with research sensors and robust field I/O. Since Leo Rover is not an autonomous navigation platform out of the box, additional electronics may be required to support LiDAR, IMU, GNSS/RTK, motor feedback, or external compute accelerators for perception workloads.

Typical Leo Rover custom electronics tasks include:

adding a regulated 12 V rail for LiDAR while keeping logic at 5 V or 3.3 V
UART or USB integration for GNSS receivers with PPS support
level shifting and signal conditioning for encoder or trigger lines
watchdog-controlled power cycling for USB sensors or companion boards
integrating a microcontroller bridge that exposes CAN or RS-485 devices to ROS 2

On Raph Rover, the larger payload envelope allows heavier compute and sensor assemblies. Here the custom electronics problem becomes more system-level. A designer may need multiple isolated rails, distributed CAN nodes, sealed connectors, and thermal-aware power design for high-power compute and long field runs.

ROS 2-facing implementation pattern

A common architecture is to place low-level custom electronics behind a microcontroller and expose a clean ROS 2 interface through a driver node. This reduces direct dependency on timing-sensitive GPIO from the main Linux computer.

custom_electronics_bridge:
  ros__parameters:
    port: /dev/ttyACM0
    baudrate: 1000000
    publish_imu: true
    publish_battery: true
    publish_encoders: true
    frame_id_imu: imu_link
    battery_topic: /battery_state
    encoder_rate_hz: 50
    imu_rate_hz: 200

ros2 topic list
ros2 topic hz /imu/data
ros2 topic echo /battery_state
ros2 run tf2_ros tf2_echo base_link imu_link

In this model, the electronics board handles acquisition and protection, while ROS 2 handles transport and composition. The separation is useful for debugging and for replacing payloads without rewriting the full robot stack.

Design constraints and trade-offs

Custom electronics improves fit and performance, but it adds verification cost. Every custom board introduces requirements for schematic review, PCB layout, thermal analysis, power validation, firmware maintenance, connector documentation, and spare part planning.

The main trade-offs are:

custom fit versus easier replacement with off-the-shelf modules
higher integration density versus more difficult field service
lower bill of materials versus longer engineering lead time
better electrical performance versus lower reuse across platforms

For research UGVs, the best approach is often mixed. Keep high-risk or fast-changing functions modular, and customize the parts that affect power integrity, synchronization, and rugged I/O.

Normative references and standards

The concept itself is broader than ROS, but its implementation in a robotics stack should align with established ROS conventions and hardware specifications. For ROS integration, the most relevant references are REP 103 for units and conventions and REP 105 for coordinate frames. For hardware interfaces, the authoritative source is the vendor specification of the actual device or module, such as NVIDIA Jetson carrier requirements, Intel RealSense interface constraints, or GNSS receiver electrical timing documentation. For mobile robot software behavior, the ROS 2 and package-level documentation remains the primary reference.

Custom Electronics