Differential Drive Mobile Robot Chassis

A differential drive mobile robot chassis, also known as a differential drive chassis, is a wheel-driven robot mobile platform. It controls the speed difference between the left and right drive wheels to enable the robot to move forward, backward, turn, and even rotate in place. This design allows the robot to maneuver flexibly in a flat environment without the need for complex steering mechanisms.

Parameter Table

Drive wheels: Two independent drive wheels on the left and right, typically powered by DC hub motors, servo motors, or steering wheels. These wheels are connected to the motor via a gearbox or direct drive.

Driven wheels or support wheels: To maintain chassis balance, typically equipped with two caster wheels or fixed wheels. These wheels do not participate in driving and are only used for support and stability.

Transmission and control system: Includes motor controllers, encoders (for measuring wheel speed), IMUs (inertial measurement units for attitude detection), and other sensors. The chassis frame is typically made of aluminum alloy or plastic for lightweight durability.

Expansion interfaces: Integrated ROS (Robot Operating System) interfaces support sensor expansions such as lidar and cameras.

The working principle of the differential drive robot chassis primarily achieves vehicle steering and power distribution under different road conditions by adjusting the speed difference between the left and right drive wheels.

Straight-line driving: The left and right wheels rotate at the same speed, and the robot moves in a straight line.

Steering: When one side's wheel speed is faster, the robot turns toward the slower side; if the wheel speeds are in opposite directions, zero-radius turning can be achieved.

Odometer calculation: Wheel speed is measured via encoder feedback, and position is estimated using an integration algorithm, but slippage errors must be accounted for.

Indoor flat hard surfaces:

Home/office: Wood flooring, tiles, marble, cement self-leveling floors. 

Warehouse/factory workshop: Flat cement floors, epoxy flooring. Used for material handling AGVs (automated guided vehicles) and inspection robots.

Shopping mall/hotel/hospital lobby: Smooth tiles, marble floors. Used for guided tours, delivery, and disinfection robots.

Data centers/laboratories: Anti-static flooring, smooth cement floors. Used for inspection robots.

Structured, channelized environments: Corridors, passageways: Wide enough for robots to pass through, with clear boundaries.

Shelf aisles: In warehouses, aisles are formed by neatly arranged shelves.

How to choose the right robot chassis for you? (Ackermann chassis and differential chassis)

1. What are the main application scenarios?

For indoor environments (warehouses, factories, homes, offices, hospitals), differential drive mobile robot chassis are mostly used. These environments often have narrow passages, require frequent turning on the spot, and operate at low speeds.

For outdoor environments (parks, roads, fields), Ackermann chassis are typically used, especially in applications requiring medium to high-speed operation, long-distance movement, and relatively flat terrain.  

2. Operating Speed  

For low-speed requirements, differential drive robot chassis are recommended due to their high flexibility and lower cost.  

For medium to high-speed applications, the Ackermann chassis must be considered, as differential chassis become unstable and dangerous at high speeds.

3. Requirements for Turning Flexibility  

If turning in extremely tight spaces or performing in-place turns is necessary, a differential robot chassis must be selected, as an Ackermann chassis cannot perform in-place turns.  

If sufficient turning space is available, either an Ackermann chassis or a differential chassis can meet your needs.

4. Requirements for positioning accuracy and odometer

If you heavily rely on the odometer for long-term/long-distance navigation and cannot frequently perform external corrections, the Ackermann chassis has an advantage (theoretically, no side slip, more accurate odometer).

If an external positioning system (LiDAR SLAM, UWB, visual positioning) is available, the odometer error of the differential chassis can be effectively compensated.

5. Payload and platform size  

For small, lightweight platforms, both Ackermann and differential steering systems are suitable.  

For medium to large, heavier platforms, the Ackermann steering system typically offers advantages in structural strength, stability, and scalability, especially when high speeds are required.