Common Issues and Solutions

This document addresses frequently encountered problems with the RCR Common Robotics Platform and their solutions.

Communication with Teensy 4.0 Microcontroller

View debug output

SERIAL_TEENSY_DEVICE=`find /dev/serial/by-id/ -name "usb-Teensyduino*if02"|head -1`
python3 -m serial.tools.miniterm ${SERIAL_TEENSY_DEVICE} 115200

Power Issues

Robot Won’t Power On

Symptoms:

  • No LED indicators

  • No response to power switch

  • Dead system

Possible Causes & Solutions:

  1. Battery Issues

    • Cause: Dead or low battery

    • Solution: Check battery voltage, charge if needed

    • Prevention: Regular battery maintenance

  2. Power Switch Failure

    • Cause: Faulty power switch

    • Solution: Test switch continuity, replace if needed

    • Prevention: Handle switch gently

  3. Loose Connections

    • Cause: Poor battery connections

    • Solution: Check and tighten all power connections

    • Prevention: Regular connection inspection

Intermittent Power Loss

Symptoms:

  • Robot shuts down unexpectedly

  • System resets during operation

  • Unstable power indicators

Solutions:

  1. Check battery voltage under load

  2. Inspect power cables for damage

  3. Verify power distribution board connections

  4. Test with known good battery

Communication Issues

ROS2 Nodes Not Starting

Symptoms:

  • Missing nodes in ros2 node list

  • Launch failures

  • Communication timeouts

Solutions:

  1. Network Issues

    # Check network connectivity
ping <robot_ip>

# Verify ROS2 environment
echo $ROS_DOMAIN_ID

  2. Launch File Problems

    # Test launch file syntax
ros2 launch --dry-run common_platform launch_robot.launch.py

  3. Dependency Issues

    # Check for missing packages
rosdep check --from-paths src --ignore-src

Sensor Communication Errors

Symptoms:

  • No sensor data on topics

  • Error messages about sensor connections

  • Inconsistent sensor readings

Solutions:

  1. USB Connection Issues

    • Check USB cable integrity

    • Try different USB ports

    • Verify device permissions

  2. Serial Communication Problems

    • Check baud rate settings

    • Verify serial port assignments

    • Test with serial terminal

  3. I2C Bus Issues

    • Check I2C device addresses

    • Verify pull-up resistors

    • Test I2C bus with tools

Motor and Movement Issues

Motors Not Responding

Symptoms:

  • No movement on command

  • Motors make noise but don’t move

  • Uneven motor performance

Solutions:

  1. Motor Driver Issues

    • Check motor driver connections

    • Verify driver power supply

    • Test driver functionality

  2. Encoder Problems

    • Check encoder wiring

    • Verify encoder counts

    • Test encoder resolution

  3. Control Loop Issues

    • Check PID parameters

    • Verify control loop timing

    • Review motor specifications

Uneven Movement

Symptoms:

  • Robot drifts to one side

  • Uneven wheel speeds

  • Curved movement when going straight

Solutions:

  1. Calibration Issues

    • Recalibrate wheel diameters

    • Check wheelbase measurements

    • Verify encoder counts per revolution

  2. Mechanical Issues

    • Check wheel alignment

    • Verify tire pressure

    • Inspect for mechanical binding

Diagnostic Commands

System Health Check

# Check system resources
htop

# Check disk space
df -h

# Check network connectivity
ip addr show

ROS2 Diagnostics

# List all nodes
ros2 node list

# Check topic rates
ros2 topic hz /${ROS_NAME}/topic_name

# Monitor system performance
ros2 run rqt_graph rqt_graph

Hardware Diagnostics

# Check USB devices
lsusb

# Check serial devices
ls /dev/tty*

# Check I2C devices
i2cdetect -y 1

When to Seek Help

Contact the PARTS team if:

  • Issues persist after trying solutions

  • Hardware appears damaged

  • Error messages are unclear

  • System behavior is dangerous

Prevention Tips

  1. Regular Maintenance

    • Clean sensors regularly

    • Check connections monthly

    • Update software regularly

  2. Proper Operation

    • Follow startup/shutdown procedures

    • Use appropriate operating environments

    • Monitor system during operation

  3. Documentation

    • Keep logs of issues and solutions

    • Document any modifications

    • Share solutions with community

For more detailed troubleshooting, see Recovery Procedures For error code reference, see Error Codes