The Past and Present of Ackermann Mobile Robots
1. The Past and Present of Ackermann Steering
Ackermann Dynamics
Originating from automotive applications, the Ackermann geometry is a fundamental mechanism designed to achieve smooth vehicle turning. When navigating a curve, the inside and outside wheels steer at different angles, allowing the inside wheel to turn along a smaller radius than the outside wheel.
This geometry was initially devised by German carriage builder Georg Lankensperger in 1817. His agent, Rudolph Ackermann, patented the invention in the UK in 1818, after which this steering geometry became widely known as Ackermann steering.
Decades earlier, however, Erasmus Darwin had already conceived the concept. The grandfather of Charles Darwin (the pioneer of evolutionary theory), Erasmus Darwin was a legendary polymath in British history—a scientist, poet, inventor, botanist, and physician.
After studying at Cambridge and Edinburgh, Darwin began practicing medicine in Lichfield at the age of 25. His exceptional medical skills brought him widespread renown—even leading King George III to invite him as court physician, an offer Darwin declined. His versatile talents established him as a key figure in the Lunar Society of Birmingham, where he developed a close friendship with James Watt, famous for improving the steam engine.
During his extensive travels by carriage to treat patients—similar to the illustration below:
Historical Carriage Steering Illustration
Covering over 10,000 kilometers annually, Darwin quickly identified two major steering flaws in traditional carriages:
(1) Obstacle clearance limitations: Because the front wheels turned on a central pivot axle, wheel diameter was restricted, making them prone to lifting over rocks and obstacles.
(2) Geometric wheel interference: Parallel front wheels forced the four wheels onto conflicting turning arcs, causing the carriage to easily lock up and skid during turns.
Driven by these challenges, Darwin began modifying his carriages. By 1766, correspondence with friends revealed that he had converted two carriages and conducted over 10,000 kilometers of road trials.
In 1767, Darwin and James Watt exchanged insights regarding steam power applications. While Watt focused on stationary industrial machinery, Darwin envisioned steam power replacing horses in road locomotion. Darwin shared chassis design sketches featuring an early linkage steering mechanism, which Watt recognized on the envelope as a rectangular linkage structure.
Original Linkage Steering Manuscript
By 1768, Darwin documented the complete trapezoidal four-bar linkage steering mechanism in his letters:
Trapezoidal Four-Bar Linkage Manuscript
This linkage mechanism was fundamentally identical to modern automotive steering geometry. However, manufacturing constraints of that era prevented widespread adoption, and four-wheeled carriages continued using center-pivot axles for another century. It was not until the emergence of the modern automobile that Ackermann steering realized its full potential.
Early Benz prototype vehicles started as simple three-wheelers, largely due to the complexity of front-wheel four-bar steering mechanisms:
Early Benz Three-Wheeled Prototype
From its second model onward, Benz permanently transitioned to four-wheeled configurations utilizing Ackermann steering, ushering in the rapid expansion of the automotive industry.
Early Benz Four-Wheeled Prototype
2. Ackermann Steering in Mobile Robotics
During the early stages of mobile robotics, two-wheel differential drive configurations were the dominant approach. Between 1956 and 2013, most mobile robotics research relied on differential steering architectures. However, these systems faced identical constraints to those encountered 250 years earlier: poor terrain passability, inability to handle heavy payloads in outdoor environments, high maintenance frequency, and limited suitability for non-structured outdoor domains.
Early Two-Wheel Differential-Drive Prototype (Stanford Research Institute, 1966–1972)
In 2013, four mobile robotics pioneers founded YUHESEN to enable intelligent mobile robots across diverse industrial environments. Lead engineer Li Leida proposed implementing the Ackermann steering mechanism to achieve scalable, all-scenario deployment. The engineering team redesigned traditional differential platforms and conducted a 3-year, 10,000-kilometer field validation program through 2016.
This breakthrough opened the door to widespread adoption, followed by large-scale commercial deployments across logistics and e-commerce leaders. Industry data indicates that as a leading mobile robot chassis provider, YUHESEN maintains an annual application growth rate of 350%–400%, driving overall industry growth beyond 100%.
3. Core Advantages of Ackermann Mobile Robots
Wheeled Ackermann mobile robot chassis platforms are purpose-built for paved road environments, addressing heavy-payload delivery up to 600kg, perimeter security patrol, autonomous cleaning, and smart mobility assistance.
The platform combines a rear-wheel differential drive axle with precise front-wheel steering angles, delivering stable forward, reverse, and radius-turning motions. With high load-bearing capacity and precise motion control, Ackermann chassis architectures represent the standard hardware configuration for modern outdoor service robotics.
