Wheeled Robots: What Types Are There?

With the development of intelligent scenarios such as industrial automation, logistics distribution, and service inspection, wheeled robots have become a choice for enterprises to reduce costs and increase efficiency. However, choosing the right wheeled robot can better meet your needs and maximize your benefits.

Wheeled robots are intelligent devices that achieve autonomous movement through wheel hubs motor. The core components include chassis, sensors, control systems, etc. The application of robot chassis varies depending on their performance. As a robot chassis supplier integrating R&D and manufacturing, XspireBot will help you understand the types of wheeled robots to help you better select robots.

Wheeled robots are divided into different types according to the number of their wheels and the mode of movement. The following are common types of wheeled robots and their characteristics:

1. Two-Wheeled Robot

Two-wheeled robots are robots with two driving wheels as the core moving parts, and achieve balance and movement through differential control. It mainly relies on forward and backward movement to achieve dynamic balance, and completes steering through the speed difference between the left and right wheels when turning. Due to its structural characteristics, the two-wheeled robot chassis (including self-balancing and differential drive) is limited in application scenarios.  (Please consult for details.)

Common problems:

Slip problem: The maximum acceleration needs to be reduced on smooth ground (such as adding acceleration ramp control).

Track drift: This is caused by insufficient encoder accuracy and can be corrected using an IMU or visual odometer.

2. Three-Wheeled Robot

The chassis structure of a three-wheeled mobile robot generally includes three wheels, usually using dual active wheels + active steering wheels or an omnidirectional three-wheel layout. Compared with the two-wheeled robot chassis, the three-wheeled robot chassis with a triangular static support structure eliminates the risk of universal wheel jamming, achieves higher positioning accuracy, greater load capacity (increased by 133%), and lower maintenance costs (failure rate reduced by 80%), and is often used for patrols and surveys in small spaces.

Note: Its triangular support is prone to overturning when the slope is >15°, and the load capacity is limited (usually <80kg); in non-paved roads or high-reliability scenarios, the failure rate and maintenance cost are higher. Once it involves complex terrain, large loads, or unattended operation, the redundant design and anti-interference ability of the four-wheel robot chassis must be considered.

3. Four-Wheeled Robot

A four-wheel robot chassis refers to a robot mobile platform that uses four drive wheels as the main means of movement. Each wheel is equipped with an independent motor and reducer to achieve precise speed and direction control.

Compared with the three-wheel robot chassis, the four-wheel chassis structure has higher stability and load-bearing capacity, making it suitable for occasions where the robot needs to carry heavy objects or travel on unstable ground.

Equipped with sensors such as radar, camera, IMU, etc., it realizes real-time map construction and navigation through SLAM technology, and achieves precise positioning and dynamic obstacle avoidance. According to different movement modes and application scenarios, four-wheel robots are specifically divided into the following types:

Differential robot chassis

The differential robot chassis is a mobile robot chassis structure that realizes steering control through the speed difference of the driving wheels on both sides. It consists of two independently driven wheels, usually located on the left and right sides of the chassis, and conductors for forward movement, turning, and other movements by adjusting the speed difference of the wheels on both sides.

Differential robots can achieve zero-radius turns and rotate in place, making them particularly suitable for indoor structured environments with flat ground and limited space (like residences, offices, warehouses, hospital corridors, and hotel passages).

Ackerman robot chassis

The Ackerman robot chassis is based on the principle of dynamic compensation of steering angle difference. When turning at high speed, the large steering angle of the inner wheel is used to suppress side slip, and the rear-drive traction force distribution is used to achieve body stability control under complex terrain; its geometric design reduces tire eccentric wear by more than 30%, supports energy efficiency improvement and operation and maintenance cost compression in long-distance heavy-load conditions, and achieves high-efficiency sports performance and low energy consumption and long endurance in complex terrain and high-load scenarios. For example:

In industrial logistics (such as warehouse AGV), its steering design can reduce the loss caused by tire side slip, while improving the path control ability in narrow spaces.

In complex terrains such as outdoor inspections or mining transportation, the chassis optimizes the steering angles of the inner and outer wheels to enhance high-speed turning stability and reduce the probability of loss of control on bumpy roads.

In heavy-load transportation scenarios (such as airports and port tractors), the front-wheel steering and rear-wheel drive design improves traction and control reliability under large loads.

Advantages: The Ackerman robot chassis is based on the geometric design of vehicle steering. It achieves precise path control through front-wheel steering. When turning, the steering angle of the inner wheel is greater than that of the outer wheel, ensuring that the extension lines of all wheels intersect at the same instantaneous steering center point, thereby avoiding lateral sliding and excessive wear of the tires during turning, making the body posture more stable, especially when turning at high speed, it can effectively reduce the risk of roll and accidental drift.

Four-turn four-wheel drive robot chassis

The four-turn four-wheel drive robot chassis is a mobile platform with four-wheel independent steering and drive. Compared to the Ackerman chassis (front-wheel steering + rear-wheel drive). The four-turn four-wheel drive chassis uses four-wheel drive + active steering to achieve regular movement modes such as lateral translation, rotation in place, and diagonal walking. At the same time, combined with dynamic terrain distribution technology, it has stronger passability and stability in complex terrain. This design is particularly suitable for harsh environments with limited space, low ground adhesion, or variable paths, such as heavy-load transportation in ports (requiring precise path tracking and high traction), agricultural mountain operations (soft ground + stable driving on steep slopes), earthquake rescue (crossing obstacles in unstructured terrain), and fire fighting.

4. Customized Solutions

Sensor system customization

Our robot chassis is based on modular design and can be equipped with sensors such as laser radar, ultrasonic radar, camera, IMU, and integrated inertial navigation. We can provide solutions according to customer needs.

Drive system customization

The moving speed and direction of the wheeled robot can be controlled by controlling the rotation speed of the wheels, and the wheels can be controlled by controlling the rotation speed of the motors. The motor plays an important driving role, enabling the robot to complete various motion tasks. Xspirebot provides hub motors and steering wheels of different sizes and powers to meet your various steering and movement needs.

Robot chassis customization

Xspirebot provides customized mobile platform solutions for two, three, four, and multiple wheels, supporting chassis size, load, speed, and other parameter customization. If you need an adaptation solution, please contact our engineering team to get a detailed parameter manual.