High-precision robots: What to do when absolute accuracy is poor?

With leading devices and years of experience, Fraunhofer IPA reaches the source of incorrect robotic procedure. Resource: Rainer Bez, Fraunhofer IPA

Robotics are generally very repeatable. Outright precision, on the various other hand, commonly leaves something to be preferred. A group at the Fraunhofer Institute for Production Design and Automation IPA is discovering the factors for this and aiding firms to attain a lot more reliable robotic systems.

Repeatability and outright precision are developed criteria for analyzing the high quality and accuracy with which a robotic executes a particular job. If a robotic executes a particular job often times with virtually the same outcomes, this shows great repeatability. Lots of commercial robotics attain worths in the series of 0.1 mm or far better.

On the other hand, outright precision defines exactly how precisely a robotic’s spatial collaborates are attained in regard to its base system, despite previous activities. And below, there is commonly still space for renovation. Generally, worths in between 0.5 and 1.5 mm are attained. This propensity towards mistake is not a trouble for some applications, however it is for others.

Downsides of incorrect robotics

It is challenging to make use of robotics with reduced outright precision in procedures that are not duplicated identically, such as in the manufacturing of little set dimensions. When welding a setting up, as an example, it is specifically crucial that the cord suggestion is located exactly in the facility of the weld joint. Specific placing cause top notch weld joints that satisfy sector needs.

Nonetheless, variances of simply a couple of tenths of a millimeter can substantially harm high quality and even cause denials. Outright precision is not just crucial for robot-based welding, however likewise for applications such as choice and location, overspray-free paint, or robot-based boring and deburring.

An additional drawback of incorrect robotics emerges in offline programs (OLP), which is likewise regularly utilized while doing sos stated over. Below, the robotic program is produced in a simulation and afterwards moved to the genuine robotic. The benefit depends on the opportunity of the robotic keeping procedure while programs is executed. Consequently, while the robotic is refining one part, the following part can be configured in parallel.

However if outright precision wants, the produced program can not be utilized straight. Rather, taxing adjustments are needed, causing undesirable maker downtime, which subsequently harms effectiveness and efficiency.

The often-achieved outright precision of 0.5 to 1.5 mm is consequently inadequate for facility applications and can restrict and even avoid making use of robotics in particular applications. It likewise regularly results in added job actions, such as the re-teaching, which lowers the effectiveness of the whole manufacturing chain. In numerous commercial circumstances, an outright precision that resembles the repeatability is preferable and even needed.

Factors for an absence of outright precision

Along with the precision dimensions supplied according to ISO 9283, firms repetitively transform to Fraunhofer IPA with the inquiry of exactly how they can boost the efficiency of their robotics in regards to accuracy. The root causes of errors are manifold and can be separated right into hardware-related, software-related, and on the surface relevant reasons.

Hardware-related factors might consist of the layout of the robotic, such as substandard encoders or equipments, or inadequate strength, whether it is a verbalized arm, a SCARA robotic, or a gantry system. Poor calibration of the robotic is among the primary factors for mistake on the software program side, together with inadequate controller efficiency.

Additionally, a raising variety of robot systems are furthermore outfitted with “cognitive” features, specifically those pertaining to understanding. These supposed closed-loop systems collaborate with sensing units that find the robotic’s atmosphere, and their software program refines the determined information to readjust the robotic’s course appropriately. In such a system, bad sensing unit information, a low-performing controller, or suboptimal communication in between the elements in the robot cell normally create issues.

Ultimately, outside aspects such as temperature level and atmospheric pressure, however likewise procedure pressures that happen, can have an unfavorable influence on outright precision.

The dimensions made by these gadgets have a precision of +- 40 µm throughout the functioning area. Resource: Fraunhofer IPA

Detailed evaluation with brand-new standard

If firms that make use of robotics, in addition to the robotic suppliers themselves, are disappointed with the outright precision of their systems, the whole application ought to be checked out and assessed. As explained over, a specific examination of the reasons is needed.

The automation group at Fraunhofer IPA is a neutral job companion that can perform this root-cause evaluation in a systematic fashion based upon substantial specialist understanding and experience.

In a normal job, the group initially tapes the existing circumstance utilizing sensing unit modern technology such as the Leica Outright Tracker AT960 to develop a strong data source. The laser tracker documents the placements of the robotic with submillimeter precision. Unique efficiency signs are computed from the tape-recorded information, which can be utilized to identify the efficiency of the robotic system.

Additionally, the attributes of the robotic’s activities are checked out, which likewise offer important understandings. In a more action, the professionals examine the source of the unfavorable actions. To do this, they check out both the software and hardware of the robotic system.

Additionally, the group has actually established a closed-loop standard especially for the closed-loop robotic systems stated over. The standard appropriates for robotics from numerous suppliers. In the standard, a reference-giving tool, a “metronome,” is utilized to prompt the robotic right into particular actions, which enables verdicts to be attracted concerning its efficiency.

While ISO 9283 just concentrates on the robotic itself to determine outright precision, the standard established can check out whatever that composes a closed-loop regulated procedure or treatment. As an example, this consists of the efficiency of the whole robot cell, consisting of the sensing unit modern technology and the desired procedure.

The benchmark treatment existed at the 56th International Robotics Seminar (ISR 2023) and at the 21st International Seminar on Automation Modern Technology and Mechanical Design (SITUATION 2025).

With a precise robotic, the intended course can be performed without hands-on communication on the genuine robotic. Resource: Fraunhofer IPA

Included worth of high outright precision

A robotic with adequate outright precision can not just change a lot more pricey devices however likewise boost adaptability and lessen rework. In numerous applications, it consequently makes good sense to examine abnormalities and boost outright precision.

A robotic that functions exactly and dependably uses financial benefits, in addition to boosts a firm’s competition. Purchasing this location is consequently a tactical choice that settles in the long-term.

Regarding the writer

Martin Finkbeiner is a task supervisor at the Fraunhofer Institute for Production Design and Automation IPA. He can be gotten to at martin.finkbeiner@ipa.fraunhofer.de and +49 711 9701046.

The message High-precision robotics: What to do when outright precision is bad? showed up initially on The Robotic Record.