## 4 Evaluations
### Setup  
An example of the setup using during both studies can be seen in Figure 7a, where the participant is placed in a wheelchair while the exoskeleton is attached to their right arm. The length of each link in the exoskeleton was adjusted to fit the participant and the kinematic model of the exoskeleton was updated accordingly. Once the exoskeleton was attached, the participant was asked to complete a small calibration procedure to find the center point of their hand. This was necessary as the soft nature of the Carbonhand meant that the participant's hand did not always end up in the same location. The calibration procedure consisted of grasping a bottle with a known position and orientation and was repeated each time the participant wore the exoskeleton. The participant was seated at a table with a computer screen, the wireless receiver for the tongue-based interface, several ArUco markers, and the objects to interact with. The computer screen is used to provide visual feedback to the user during the experiment. The screen displayed visual feedback for the tongue-based interface while the user learned to control it during the first days of the study. When testing the control schemes, the screen is only used to display the current control scheme to the participant. The ArUco markers were added to make it possible to cross-reference recorded images and videos from multiple sources. Finally, the objects on the table included either a plastic bottle or a plastic strawberry, as shown in Figure 7b. Both objects are bright red to make detection easier. These two objects could be placed in two predefined positions, as illustrated by the markers under each object. The choice of using a strawberry and a bottle was to have a larger object which was easy to grasp and to have a smaller object which would be more difficult to grasp. Grasping the strawberry would, in most cases, require the participant to rotate the wrist of the exoskeleton. This was not necessary in the case of the bottle. Four possible test scenarios were constructed from these two objects:  
* **Bottle--Single:** Only the bottle is present in one of the two predefined positions. The user must grasp and lift the bottle. * **Strawberry--Single:** Only the strawberry is present in one of the two predefined positions. The user must grasp and lift the strawberry. * **Bottle--Multi:** Both the bottle and the strawberry are present and placed in the two predefined positions. The user must grasp and lift the strawberry. Figure 7: An overview of the test setup. (**a**) The participant is placed in a wheelchair with the exoskeleton attached to the right arm in the starting position. In front of the participant is a table with different objects to grasp. (**b**) The two objects used in the studies for the task of grasping: a plastic strawberry and a plastic bottle. The objects can be placed on the two predefined positions marked on the table below the objects. The test scenarios were constructed to create both easy and difficult situations. In easy scenarios, with only a single object, the intention prediction would always be correct. In the more challenging scenarios, with two objects, the intent prediction could possibly be wrong, and the participant would also have to avoid collision with the object not to grasp. Furthermore, the test scenarios involving the strawberry are anticipated to be more difficult due to its smaller size and as it requires using the wrist rotation of the exoskeleton in order to grasp it. A video of a few trials from study A can be found in Supplementary Materials. Each trial started with the exoskeleton being in a predefined home position, as shown in Figure 7a. The participant was then told what control scheme was active, and what object to grasp and lift; afterwards, they could start moving the exoskeleton. The start of each trial is marked by the participant starting to move the exoskeleton, and the trial ends once the participant has grasped and lifted the object from the table for a few seconds.