scope:

Objective and scope

By the "quality" of a technical system, one generally understands the degree to which it approaches its ideal behaviour.

The motion systems to be considered and the controlled sequences of motion in production plants and conveying equipment are extremely varied. The weighting of the individual criteria is therefore varied, too, and is a consequence of the desired function.

This guideline aims at presenting objective criteria for the comparative assessment of motion systems and sequences of motion, which are valid irrespective of the technical implementation. In addition to classical characteristics of position-controlled systems, like

• position error

• velocity error

• acceleration error

it is for economical, ergonomical, and ecological considerations that criteria such as

• investments in equipment

• energy consumption

• wear

• noise generation

• heat generation

are also to be taken into account. In addition to quantifiable criteria others can at least be derived from them in a qualitative manner; examples are overtemperature, noise generation, wear.

As a matter of course, any actual machine must first and foremost fulfil its technical function (motion and action of force) at the point of action, i.e. the point of processing. Not fulfilling this function is a disqualification criterion. The comparative criteria mentioned above serve for comparative quality assessment. They are typical of specific technical solutions, but their validity is limited.

Prior to assessing the quality of different solutions, the task, i.e. the motions to be executed, must be defined exactly. In addition to a description of the continuous movement, specify, e.g., discrete events during the sequence of motion, cycle times, or synchronisation conditions (see also VDI/VDE 3684).

This guideline exclusively deals with periodic sequences of motion, and with the quantifiable criteria

• precision of the sequence of motion

• energy efficiency

• stress limits in the electromechanical system

The quality criteria are an aid to developers as well as users of motion systems in specifying objective parameters of quality and in using these parameters as the basis of contractual agreements, thus rendering the course of development more reliable. Furthermore, the quality criteria allow the objective comparison of competing products.