In intelligent manufacturing and intralogistics automation scenarios, the mobility system of AGVs (Automated Guided Vehicles) directly determines overall motion accuracy, load capacity, spatial adaptability, and cost efficiency. As the three core components of the AGV chassis, drive wheels, steering wheels, and caster wheels not only influence individual performance metrics, but also define the system-level performance of the entire vehicle.

With the rapid evolution of flexible manufacturing, leading solution providers such as Plutools have been continuously optimizing core mobility modules-especially integrated steering drive systems-to meet increasingly demanding industrial applications. Based on engineering practices and product-level implementation experience, this article provides a systematic breakdown of these three components, combined with motion models and real-world design considerations.

1. Drive Wheel: Technical Characteristics and Application Boundaries of Differential Drive Systems

The drive wheel is the core execution unit for AGV power output. In medium and small load scenarios, differential drive remains the dominant solution due to its structural simplicity and cost advantages. Its fundamental principle is to achieve steering and motion control through the velocity difference between the left and right drive wheels.

1.1 Core Motion Principle of Differential Drive

The motion of a differential drive AGV is entirely determined by the linear velocity difference between the two drive wheels. Whether moving straight, turning, or rotating in place, all motions can be realized through coordinated wheel speed control. The core relationship is:

v_diff = v_L - v_R

Where v_L and v_R represent the linear velocities of the left and right drive wheels, and the velocity difference v_diff determines the steering behavior of the vehicle. When the wheels rotate at equal speeds in opposite directions, the AGV achieves zero-radius rotation, with angular velocity expressed as:

ω = 2v / B

This model forms the basis of motion control and odometry algorithms in differential drive systems, but also highlights the system's sensitivity to wheel speed consistency and ground conditions.

1.2 Technical Characteristics of Differential Drive Wheels

From an engineering perspective, the primary advantage of differential drive lies in its simplicity. Without requiring an independent steering mechanism, the system can be controlled using only two drive motors, resulting in lower implementation complexity and cost. In confined environments, its ability to rotate in place provides sufficient maneuverability for many standard applications.

However, this structure also introduces inherent limitations. Since all motion depends on the speed difference between two wheels, even minor discrepancies in velocity or variations in surface friction can accumulate into positioning errors. Under high-speed or heavy-load conditions, these errors may lead to slipping or trajectory deviation. In addition, the lack of lateral mobility prevents true omnidirectional movement, which becomes a constraint in advanced manufacturing environments.

1.3 Application Boundaries of Differential Drive Wheels

Based on these characteristics, differential drive wheels are best suited for medium and small load applications with moderate precision requirements, such as basic material handling, early-stage navigation AGVs, and cost-sensitive automation projects. In these scenarios, their cost-performance advantage remains highly competitive.

2. Steering Wheel: Integrated Drive and Steering Solution for High-End AGV Systems

Unlike differential drive systems, steering wheels integrate driving, steering, and load-bearing functions into a single module, making them the key technology for achieving omnidirectional movement. Their performance level often defines the overall capability of high-end AGVs.

2.1 Technical Constraints in Early Steering Wheel Adoption

Despite their advantages, steering wheels were not widely adopted in early stages due to several constraints. Structurally, early designs often had installation heights exceeding 250 mm, which conflicted with the compact requirements of under-ride AGVs. From an application standpoint, early logistics systems were primarily unidirectional, where differential drive solutions were sufficient, reducing the immediate need for omnidirectional capability.

In addition, early steering wheel systems relied heavily on imported components, resulting in high costs and limited accessibility. This further slowed adoption in cost-sensitive industrial environments.

2.2 Core Technical Advantages of Steering Wheels

With the increasing demand for flexibility and precision in modern manufacturing, steering wheel solutions have become the preferred choice for advanced AGV systems. Their most significant advantage is true omnidirectional mobility. Through independent steering and driving control, AGVs can perform lateral movement, diagonal motion, and in-place rotation, significantly improving space utilization in complex environments.

In terms of precision, modern steering wheels are typically equipped with high-performance servo systems and absolute encoders, achieving steering repeatability up to ±0.1°, which meets the requirements of high-precision docking operations. The high level of integration also allows a single steering module to replace multiple differential drive units, simplifying chassis design and improving reliability.

In this context, Plutools PLT Series Steering Drive Wheels represent a new generation of integrated drive solutions. By combining compact structural design, high-torque servo drive systems, and precision steering control, the PLT series enables AGVs to achieve both high load capacity and high positioning accuracy within limited installation space. This makes them particularly suitable for under-ride AGVs, lifting AGVs, and heavy-duty mobile platforms.

2.3 Development Trends of Steering Wheel Technology

Steering wheel technology is evolving rapidly toward miniaturization, modularization, and higher precision. Through optimized mechanical design and motor integration, low-profile steering wheels with installation heights below 200 mm are now available, significantly expanding their application range.

At the same time, the integration of drive, steering, braking, and sensing functions into standardized modules has greatly simplified system integration. The PLT series by Plutools, for example, adopts a modular architecture that allows for easier installation, maintenance, and scalability across different AGV platforms.

With the adoption of advanced control algorithms and absolute encoder technologies, steering accuracy continues to improve, further strengthening its role in high-end manufacturing environments.

2.4 Typical Application Scenarios of Steering Wheels

Steering wheels are widely used in under-ride AGVs, lifting AGVs, and high-precision production environments such as automotive manufacturing, 3C electronics assembly, and new energy industries. In heavy-duty applications, especially those involving ton-level loads, integrated steering drive systems like the PLT Series Steering Wheels from Plutools have become the mainstream solution due to their superior load capacity, precision, and reliability.

3. Caster Wheel: Key Engineering Element for Passive Support Systems

Compared to drive wheels and steering wheels, caster wheels do not provide power output, but their influence on system performance is critical. As passive support components, they directly affect the stability, smoothness, and service life of AGVs.

3.1 Core Physical Parameters for Caster Wheel Selection

In practical engineering design, caster wheels must be carefully matched with the chassis structure. It is essential to ensure that caster wheels share the same load plane as drive or steering wheels, with installation height deviations typically controlled within 2 mm to avoid uneven load distribution.

Load capacity must be calculated with a safety margin, ensuring each caster can handle its share of the total load plus at least 20% additional capacity. Wheel diameter and width also play key roles, influencing obstacle-crossing ability, rolling resistance, and ground contact characteristics.

In space-constrained layouts, the rotation envelope of the caster must be evaluated to avoid interference. The relationship can be expressed as:

R_rotate = sqrt((L_wheel / 2)^2 + H_install^2)

Where:
L_wheel = wheel diameter (mm)
H_install = installation height (mm)

This formula serves as a critical constraint in chassis layout optimization.

3.2 Engineering Considerations for Caster Wheel Selection

Material selection depends on application conditions. Polyurethane wheels are suitable for clean environments, rubber wheels perform better on rough surfaces, and nylon wheels are preferred for heavy-duty applications due to their durability. Structurally, fixed casters enhance directional stability, while swivel casters improve maneuverability, and both are typically combined based on system requirements.

Manufacturing precision, including bearing quality and wheel roundness, directly affects operational noise and motion stability, making it an important consideration in high-end applications.

3.3 Typical Application Scenarios of Caster Wheels

Caster wheels are widely used as support components in AGV chassis systems and can also be applied in passive traction AGVs. In heavy-duty applications, they function as auxiliary load-bearing units working alongside the main drive system.

4. System-Level Selection Logic of the Three Core Components

From a system design perspective, drive wheels, steering wheels, and caster wheels must be selected as an integrated solution rather than independent components. When cost is the primary concern and precision requirements are moderate, differential drive combined with swivel casters remains the most cost-effective approach.

In applications requiring high precision and operation in confined spaces, steering wheels-particularly integrated solutions like the Plutools PLT Series-combined with fixed casters offer superior performance. For heavy-duty systems, multi-steering-wheel configurations supported by high-load casters provide optimal balance between structural stability and motion control.

5. Conclusion

The evolution of AGV mobility systems is fundamentally driven by the continuous optimization and integration of drive wheels, steering wheels, and caster wheels. Differential drive solutions will continue to serve cost-sensitive applications, while steering wheels are becoming the standard for high-end AGVs due to their omnidirectional capability and precision.

With ongoing advancements in modular design and control technology, products such as the Plutools PLT Series Steering Drive Wheels are playing an increasingly important role in enabling high-performance AGV systems. As intelligent manufacturing continues to evolve, the coordinated design of these three components will remain the key factor in achieving optimal system performance.