# Impact of a Robot Manipulation on the Dimensional Measurements in an SPC-Based Robot Cell
## 3 Materials and Methods
### Measurement Scenarios  
To investigate the robot movement's influence that occurs prior to a dimensional measurement on the final measured values, we divided the robot's tasks into functions, such as grip, rotation, and translation, which were the basis for the composition of nine different robot scenarios (Table 1). In all scenarios, and for all codes, the Renishaw Equator was used as the measuring device. Various scenarios are defined, programmed, and verified, from no robot manipulation to full robot manipulation, and their short descriptions, together with the used measurement method, are listed in Table 1.  
Scenario 1 represents no robot manipulation. The measured object is inserted into a fixture inside the Equator working area with no additional robot manipulation. The fixture is placed firmly at the very beginning and locked with a pneumatic system in the Equator system's measuring area. The measured object is being positioned in the measurement area, without any interruption at all over time, without any removal or external interference. Only the Equator measurement device makes contact during the measurement itself. Therefore, this situation is the best possible environment, where the measurement error is equal only to the capability of the Equator and the supporting fixture of the measured object. The subsequent scenarios are adding more manipulative gestures to the primary scenario 1. In scenario 2, only a short and simple gripping sequence is superimposed to investigate how much the gripping of the object, placed in the fixture, influences the measurements. The robot approaches the object (from a distant point outside the Equator working area) that is already in a fixture and has just been measured, grasps with the gripper, and makes a release immediately, without any robot movement during this time. Then, the robot retracts from the object and moves outside the Equator working area. Further scenarios 3 to 6 represent other, different starting displacements of the object, such as translation along the vertical z-axis, rotation around the vertical z-axis, or a combination of both. Different starting displacements correspond to different robot motions for placing the object in the measuring position. In scenario 3, the object is already in a fixture and has been measured, the robot approaches the object from a distant point outside the Equator working area, grasps it, and does a simple translation along the z-axis  
Figure 4: Demonstration of the measured characteristics with tolerances for the product PKR. Figure 3: Demonstration of the measured characteristics with tolerances for the product Magnet. for 20 mm. This is followed by a backward movement and placement of the object in a fixture. The robot then moves away, and a subsequent measurement with the Equator is begun. In scenario 4, as well, the object is in a fixture and has just been measured. The robot approaches the object from a distant point outside the Equator working area, grasps it, and makes a rotation around the z-axis by 15 degrees. The opposite rotation back to the original pose is executed, the object is released, the robot moves away, and the measurement commences. A translation along the object's z-axis involves the movement of three robot joints (2, 3, and 4), while rotation about the object's z-axis involves two robot joints (1 and 5). Scenario 5 represents a combination of scenario 3 and 4; thus, translation for 20 mm and rotation by 15 degrees with the robot are applied after object grasping. Any other procedures are the same as in the scenarios mentioned before. In scenarios 3 to 5, there is no release of the object between the individual measurements. After the measurement, the robot approaches the object from a distant point outside the Equator working area, grasps it, and moves to a displaced position. Insertion into the fixture is followed, and the robot releases the object and moves away. In scenario 6, releasing the object after moving into a displaced position is added.