Exploring the Differences: Solid-State LiDAR vs Mechanical LiDAR

LiDAR (Light Detection and Ranging) technology has revolutionized the fields of automotive, robotics, surveying, and more. In the quest for accurate and reliable distance sensing, two main types of LiDAR systems have emerged: solid-state LiDAR and mechanical LiDAR. Each type has its own advantages and disadvantages, and the choice between the two often depends on the specific application and requirements. In this article, we delve into the intricacies of both solid-state and mechanical LiDARs, comparing their key features and exploring their use cases. By understanding these differences, we can make informed decisions when choosing the right LiDAR technology for our needs.

Defining Solid-State LiDAR

Solid-State LiDAR constitutes a variant of light detection and ranging (LiDAR) technology, distinguished by its independence from mechanical moving components for measurements and scanning. Utilizing optoelectronic devices and phase control techniques, Solid-State LiDAR governs emitted and received laser pulses, thereby facilitating distance and depth measurements of target objects and subsequently generating three-dimensional spatial information.

Although the operational principles of Solid-State LiDAR resemble those of traditional LiDAR systems, which calculate distance by emitting and receiving reflected laser pulses, the former diverges in its implementation. Rather than relying on mechanical rotation for laser beam scanning, Solid-State LiDAR employs electronic means to control and direct the laser beams, obviating the need for mechanical movement.

Taking a linear array Solid-State LiDAR (25-300mm) as an illustrative example:

1. Power Consumption Test

Test Method: Employ a stable 5V output from the experimental power supply, measure current using an ammeter, and calculate to obtain power data.

Test Procedure: After powering up for the test, the working voltage and current are measured as per the table below.

Test Result: Based on calculations, the actual operating power is 0.7W.

2. Distance Range, Accuracy, and Resolution

Test Method: Measure indoor and outdoor distance range and errors by comparing with a scale.

Test Procedure: Record indoor and outdoor measurement data in a table and calculate errors, as shown in the table below.

Test Result: Indoor measurement range and errors fall within specifications; LiDAR resistance to ambient light is 25klx; the inability to detect beyond 200mm outdoors is considered normal.

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3. Angular Range, Blind Zone, and Resolution

Test Method: Calculate the LiDAR's field of view and angular resolution using data feedback from the radar host.

Test Procedure: Place obstacles at 50mm, 100mm, and 150mm from the radar to measure angles, and record adjacent angle data at the 50mm mark to calculate angular resolution.

Test Result: Based on tests and calculations, the measured angle is 109°, with a blind zone of 25mm and a maximum resolution of 0.765°.

Defining Mechanical LiDAR

Mechanical LiDAR is a light detection and ranging (LiDAR) technology that calculates the distance and position of target objects by emitting and receiving reflected laser pulses, subsequently generating three-dimensional spatial information. Characterized by its utilization of mechanical rotating components, such as motor-driven lenses or rotating platforms, Mechanical LiDAR facilitates the scanning of laser beams.

Taking the RPLIDAR A3 - 360° Slamtec LiDAR Ranging Kit as an illustrative example:

1. Power Consumption Test

Test Method: Employ a stable 5V output from the experimental power supply, measure current using an ammeter, and calculate to obtain power data.

Test Procedure: After powering up for the test, the working voltage and current are measured as per the table below.

Test Result: Based on calculations, the actual operating power is 1.9W.

2. Distance Range, Accuracy, and Resolution

Test Method: Measure indoor and outdoor distance range and errors by comparing with a scale.

Test Procedure: Record indoor and outdoor measurement data in a table and calculate errors, as shown in the table below.

Test Result: Indoor and outdoor measurement ranges of 18m each, with errors falling within specifications.

Indoor and outdoor test deviation range value (outdoor 18m, indoor 18m)

3. Angular Range, Blind Zone, and Resolution

• Test Method: Calculate LiDAR's field of view and angular resolution using data feedback from the radar host software.
• Test Procedure: Place obstacles at 50mm, 100mm, and 150mm from the radar to measure angles, and record adjacent angle data at the 50mm mark to calculate angular resolution.
• Test Result: Based on tests and calculations, the measured angle is 360°, with a blind zone of 0.2 meters and a resolution of 0.225°.
   

Comparing Key Features and Advantages

• Size and Design: Solid-state LiDAR systems are known for their compact size and lack of moving parts, making them more resilient to vibrations and allowing for easier integration into various applications. Mechanical LiDAR systems tend to be bulkier due to the inclusion of rotating parts, and their cylindrical design limits placement options.

The comparison pictures are as follows:

• Durability: With no moving parts, solid-state LiDARs are less prone to mechanical wear and tear, resulting in a longer lifespan and lower maintenance requirements. Mechanical LiDARs, with their moving components, may require more frequent maintenance and have a higher risk of mechanical failure.
• Field of View: Mechanical LiDARs have the advantage of achieving a 360-degree horizontal FoV, providing a comprehensive view of the surrounding environment. Solid-state LiDARs may have a more limited FoV but can still achieve a wide horizontal and vertical FoV through electronic beam steering.

The comparison pictures are as follows:

• Cost and Manufacturing: Solid-state LiDARs are often more cost-effective to manufacture and can be produced at scale due to their simpler design and fewer components. Mechanical LiDARs, with their more complex design, may have higher production costs.

Applications and Use Cases

• Automotive and ADAS (Advanced Driver Assistance Systems): Solid-state LiDARs are commonly used in ADAS for collision avoidance, lane departure warning, adaptive cruise control, and more. Their compact size allows for easy integration into vehicles. Mechanical LiDARs are also used for autonomous vehicle applications, where their 360-degree FoV provides comprehensive environmental awareness.

• Robotics and Automation: In robotics, solid-state LiDARs are used for navigation, obstacle detection, and path planning. Their compact and durable design makes them suitable for integration into robotic systems. Mechanical LiDARs are used for applications that require full 360-degree coverage, such as autonomous mobile robots operating in dynamic environments.
• Surveying and Mapping: Mechanical LiDARs are often preferred for aerial and terrestrial surveying applications due to their ability to capture a complete view of the landscape. Solid-state LiDARs, with their high resolution and accuracy, are also used for topographic mapping and precise measurements.
• Industrial and Safety Applications: Solid-state LiDARs are used for industrial automation, monitoring, and quality control due to their high accuracy and reliability. They also play a role in safety applications, such as worker detection in hazardous areas and perimeter security.
• Smart Cities and Infrastructure: Solid-state LiDARs contribute to the development of smart cities by providing real-time data for traffic management, pedestrian detection, and infrastructure monitoring. Mechanical LiDARs are used for large-scale mapping and city planning.

Conclusion

LiDAR technology has come a long way, and the availability of both solid-state and mechanical LiDARs allows for a wide range of applications across various industries. Solid-state LiDARs, with their compact and durable design, are a popular choice for automotive, robotics, and industrial applications. Mechanical LiDARs, with their comprehensive 360-degree FoV, excel in surveying, mapping, and autonomous vehicle applications.

Ultimately, the choice between solid-state and mechanical LiDARs will depend on the specific requirements of the application. By understanding the key differences and advantages of each type of LiDAR, we can make informed decisions that lead to successful outcomes.

References

https://zhuanlan.zhihu.com/p/349839628

https://www.zhihu.com/question/452983786

https://www.youtube.com/watch?v=ceWjU4A3yG4