A Taxonomy of Testing Activities in Product Development

We propose a taxonomy for categorizing testing activities on distinct levels with respect to the type of knowledge they are intended to provide. Our taxonomy adds to the well-established testing categories validation and verification the categories of experiment and trial-anderror. This theoretical model should help practitioners and educators to understand and explain different types of tests and to pass on knowledge

Dynamic Monitoring Reveals Motor Task Characteristics in Prehistoric Technical Gestures

<div><p>Reconstructing ancient technical gestures associated with simple tool actions is crucial for understanding the co-evolution of the human forelimb and its associated control-related cognitive functions on the one hand, and of the human technological arsenal on the other hand. Although the topic of gesture is an old one in Paleolithic archaeology and in anthropology in general, very few studies have taken advantage of the new technologies from the science of kinematics in order to improve replicative experimental protocols. Recent work in paleoanthropology has shown the potential of monitored replicative experiments to reconstruct tool-use-related motions through the study of fossil bones, but so far comparatively little has been done to examine the dynamics of the tool itself. In this paper, we demonstrate that we can statistically differentiate gestures used in a simple scraping task through dynamic monitoring. Dynamics combines kinematics (position, orientation, and speed) with contact mechanical parameters (force and torque). Taken together, these parameters are important because they play a role in the formation of a visible archaeological signature, use-wear. We present our new affordable, yet precise methodology for measuring the dynamics of a simple hide-scraping task, carried out using a pull-to (PT) and a push-away (PA) gesture. A strain gage force sensor combined with a visual tag tracking system records force, torque, as well as position and orientation of hafted flint stone tools. The set-up allows switching between two tool configurations, one with distal and the other one with perpendicular hafting of the scrapers, to allow for ethnographically plausible reconstructions. The data show statistically significant differences between the two gestures: scraping away from the body (PA) generates higher shearing forces, but requires greater hand torque. Moreover, most benchmarks associated with the PA gesture are more highly variable than in the PT gesture. These results demonstrate that different gestures used in ‘common’ prehistoric tasks can be distinguished quantitatively based on their dynamic parameters. Future research needs to assess our ability to reconstruct these parameters from observed use-wear patterns.</p></div

Tool path of one cycle for the PT gesture (top) and the PA gesture (bottom).

<p>The tool is depicted from side view for three time instances. The angle between workpiece and plane surface of the scraper is denoted as working angle. The user operates the tool standing at the left hand side.</p

Illustration of tool handling during the PT gesture on fresh hide.

<p>The subject grasps the tool at the shaft. Hand torque is required in order to apply force to the tool tip (illustrated as black arrow).</p

Plots of position, orientation, torque and force over time.

<p>The data shows two cycles of the PA gesture. Axes are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134570#pone.0134570.g006" target="_blank">Fig 6</a>. The position represents the location of the tip of the tool relative to the camera. The <i>z</i> position is plotted in a different scale than <i>x</i> and <i>y</i> position due to a lower range. The orientation of the tool is represented by <i>roll</i>-<i>pitch</i>-<i>yaw</i> local Euler angles. The data for torque shows the magnitude experienced by the tool at the location of the sensor. The Force experienced by the tool is depicted in tool frame and the force on the workpiece is depicted in camera frame. Additionally, shear force <i>F</i>_<i>s</i> is shown in camera frame.</p

The contribution of gesture in the formation of tool use wear.

<p>Wear due to repeated use of a tool to work a second material is dependent on the physical properties of the contact materials, the duration of the action [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134570#pone.0134570.ref033" target="_blank">33</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134570#pone.0134570.ref035" target="_blank">35</a>], as well as on the dynamics [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134570#pone.0134570.ref036" target="_blank">36</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134570#pone.0134570.ref038" target="_blank">38</a>], which, in the context of tool use, are dictated by the chosen gesture.</p