What are the advantages of the Ackerman steering

Ackermann steering


An alternative to the wheel-side steering, which is used on most VolksBot models, is the steering knuckle. It was patented by Rudolph Ackermann in 1816 and is therefore also named after him.
With the Ackermann steering, each wheel on the steered axle is turned independently and has different steering angles. In the automotive industry, the correct steering angles are usually implemented using a mechanical arrangement, the steering trapezoid (see figure on the right). The correct steering angle for each wheel (also called Ackermann angle) depends on the dimensions of the vehicle (wheelbase, track width, steering radius).
In the VolksBot project, the mechanical construction of a steering trapezoid was dispensed with and instead a separate steering drive was implemented for each steered wheel. The calculation of the Ackermann angle is done by the software, whereby the above-mentioned dimensions of the vehicle are made available to the software as input parameters. As a result, the greatest possible flexibility in the dimensioning of the vehicle is retained and larger steering angles can be implemented.
In order to maintain good driving characteristics even with large steering angles, the drive was relocated to the steered axle.

Our solution based on Volksbot components includes:

  • Two UDUs (Universal Drive Units)
  • Four wheels 260 x 85 mm
  • Wheelbase: 560 mm
  • Track width: 436 mm
  • Steering radius: 62.5 mm
  • Max. Steering angle: + - 60 °
  • Max steering speed: 33 ° / s
  • Integrated shock absorbers
  • Steering drive: 2 Maxon DC motors 22 W, each with 2 planetary and worm gears and 2 Maxon EPOS 24/2 motor controllers
  • Travel drive: 2 Maxon EC Flat motors 90 W, 2 Harmonic Drive gears and 2 Maxon EPOS 24/5 motor controllers
  • Power supply: Two lead-gel batteries, 12 Volts, 15Ah
  • VolksBot Power Unit (SPU) with power supply 24V / 20A, 12V / 5A, 5V / 5A
  • Software connection via C ++ libraries for Windows and LinuX including the control modules for calculating the different Ackermann angles and driving speeds for the left and right side.