In mobile robotic systems such as AMRs, service robots, material transport robots, and food or medical delivery robots, positioning plays a critical role in ensuring operational accuracy and safety.

To help robots understand and interact with their surroundings, three major sensing technologies are commonly used today:

• Lidar (Light Detection and Ranging)
• ToF (Time of Flight Camera)
• Ultrasonic Sensors

Each technology serves a unique role in mapping, obstacle avoidance, and real-time localization.

Lidar – The “360° Vision” of Mobile Robots

Lidar works by emitting laser beams and calculating the reflection time to measure distances to surrounding objects. The collected data is then used to generate 2D or 3D maps for robot navigation.

Advantages of Lidar

• High accuracy (±2–3 cm)
• 360° environmental scanning capability
• Stable performance in low-light environments
• Excellent support for SLAM and real-time mapping

Typical Applications

• Primary navigation for AMR robots
• Mapping factories, hospitals, and hotels
• Reducing collision risks during high-speed operations

Limitations

• Sensitive to glass and light-absorbing materials such as black fabric
• Higher investment cost compared to other sensor technologies

Today, most modern AMR systems use Lidar as their main navigation sensor.

ToF Cameras – Intelligent Depth Sensing Technology

ToF cameras emit infrared light and calculate reflection time to measure image depth, enabling robots to create a 3D perception of the surrounding environment.

Advantages of ToF Sensors

• Excellent detection of small obstacles
• Ability to classify objects by shape and depth
• Improved low-level obstacle detection where Lidar may struggle

Typical Applications

• Short-range obstacle detection
• Human movement recognition
• Navigation inside elevators and narrow corridors
• Detection of steps and floor gaps

Limitations

• Can be affected by strong lighting conditions
• Shorter sensing range compared to Lidar

ToF technology is often combined with Lidar to improve safety in human-centered environments.

Ultrasonic Sensors – The Final Safety Layer

Ultrasonic sensors work by emitting high-frequency sound waves and measuring reflection time to calculate distances to nearby objects.

Advantages of Ultrasonic Sensors

• Low cost
• Reliable detection of soft or light-absorbing objects
• Stable operation in dusty or humid environments

Typical Applications

• Close-range safety zones
• Emergency stopping when obstacles are too close
• Wall-following and corner navigation support

Limitations

• Lower resolution
• Cannot recognize object shapes
• May experience interference in noisy environments

Although often considered a secondary sensor, ultrasonic technology plays a critical role in industrial robot safety standards.

Quick Comparison of the Three Sensor Technologies

Conclusion: Why Modern Robots Need Multiple Sensor Technologies

Modern mobile robots do not rely on a single sensor. Instead, they use sensor fusion — combining Lidar, ToF, and ultrasonic sensors — to ensure:

• Accurate navigation in complex environments
• Detection of small, soft, or low-profile obstacles
• Enhanced close-range safety
• Stable operation under different lighting, dust, or reflective conditions

Thanks to this combination, AMR robots can operate efficiently in factories, hospitals, hotels, airports, and other environments that require extremely high safety standards.

If your business is looking for AMR robot solutions or intelligent sensor-integrated robotic systems for warehouse automation and logistics operations, Pan Robotics is ready to provide consultation and deployment support tailored to your actual operational needs.