ACCURACY
Why is the Archimedes Drive so accurate?
In gearboxes and mechatronic setups, accuracy is crucial on two fronts: at the component level, where even small discrepancies matter, and at the system level, where these discrepancies can amplify into major positioning errors.
Errors that lead to the poor positioning accuracy of robots can be divided into two categories: geometric errors and non-geometric errors.
- Geometric errors are caused by manufacturing: they are the discrepancies between a system’s designed kinematic parameters (like link lengths, offsets, joint angles, and twists) and the actual physical build, which lead to positioning deviation.
- Non-geometric errors are dynamic deviations in positioning caused by effects like joint deformation, backlash, and other load-dependent phenomena.
However, it is difficult to compensate for the non-geometric errors by modelling. Those errors come from the component nature of the system, which is where the Archimedes Drive Delivers a major advantage. As a very accurate component, it results in limiting the non- geometric errors.
When it comes to transmission systems in a mechatronic system: Accuracy values represent the difference between the theoretical angle and the actual angle of output for any given input. When we say the Archimedes Drive is “very accurate,” we mean that for any given input, the resulting output angle closely matches the target angle, leaving only a minimal difference between the commanded position and the actual position.
Our goal in this series of articles is to substantiate this claim with empirical evidence. Moreover, we will focus on accuracy alone, not repeatability. As repeatability is relatively easier to obtain with stable control algorithms and a well-calibrated system. Accuracy, however, requires precise mechanical design, high stiffness, and elimination of backlash and compliance—factors that the Archimedes Drive optimizes inherently.
“Repeatability is doing the same task over and over again, while accuracy is hitting your target each time.”
— Ahmed Joubair, Ph.D
Because we aim to demonstrate how the Archimedes Drive achieves high accuracy, the following key attributes will be examined:
– High Stiffness (1):
The Archimedes Drive exhibits exceptionally high torsional stiffness, ensuring that the torsional force from the motor at the input has negligible impact on the output position. This results in a minimal angular difference between the reference position and the actual position of the output.
– Absence of Backlash and the effect of minimal lost motion (2):
A defining feature of the Archimedes Drive is its True Zero backlash. The elimination of backlash, combined with its high stiffness, yields a very flat hysteresis curve. The zero backlash characteristic of the drive contributes by eliminating mechanical play that could otherwise distort the output.
– Efficient Control System (3):
These attributes collectively confirm the Archimedes Drive’s ability to place the output exactly where it should be—meeting the stringent accuracy requirements of high-performance mechatronic applications. In the sections to follow, we will delve into each of these factors to illustrate why the Archimedes Drive stands out as an exceptionally accurate solution.
Read our following three articles to learn more about:
1
2

Archimedes Drive: Revolutionary Stiffness for Precision Robotics
Explore how the Archimedes Drive maximizes accuracy through unparalleled stiffness, optimized stress distribution, and advanced torsional resistance.