# A Prototype Mechatronic Device for Upper Limb Rehabilitation and Analysis of Its Functionality
## 4 Device Functionality  
### Execution of the BBT Task on the Rehabilitation Device  
Prior to the commencement of a rehabilitation session, the device undergoes a calibration procedure tailored to the user's specific functional impairments and the current motor capabilities of the upper limbs. An initial assessment is conducted using dedicated software that allows adjustments in arm inclination and length, thereby determining the optimal range of motion for the exercises.  
To assess the appropriate task difficulty level, the task modules are first positioned accordingly. The user is then prompted--via visual and optionally auditory cues--to press  
Figure 15: Block diagram of the calibration algorithm for the rehabilitation training device.  
designated control buttons. This interaction enables the supervising clinician to make a preliminary evaluation of the patient's upper limb mobility. Following this, the storage container is loaded with test objects.  
The time elapsed between object detection in the designated slot and the button press is recorded. This measurement--along with task accuracy--provides an early indication of the user's motor function and informs the selection of objects suited to their abilities.  
Based on these outcomes, the system proposes specific training routines involving transferring objects from the central module to the peripheral task containers, placing them into the corresponding slots on the overlays. The system is capable of recording and analysing performance data, including completion times, enabling the monitoring of user progress and improvements in movement efficiency over time.  
To enable a precise control over tasks' difficulty, the system incorporates objects of varying colours, dual-colour variants, and diverse geometric shapes. The adjustable position of the mechanical arms further allows therapists to manipulate the movement trajectory, introducing spatial variability into the task. Moreover, the use of objects with different dimensions and surface textures stimulates tactile receptors in the palm and fingers, contributing to enhanced somatosensory feedback.  
A variety of exercise configurations are supported, with representative scenarios illustrated in Figure 16a-f. Tasks may require a full limb extension, for example  
* Ipsilateral object placement (same side as the active limb; e.g., Figure 16a,c);
* Contralateral object placement (opposite side of the active limb; e.g., Figure 16b,f);
* Cross-body manipulations (right limb operating in the left-side field or vice versa);
* Combinations of manipulation zones and containers.  
Each configuration targets specific joint actions and ranges of motion, including shoulder flexion/extension, elbow bending, and wrist articulation (Figure 16). These spatially distinct exercises activate different motor pathways, promoting a comprehensive upper limb rehabilitation.  
Figure 16: Basic exercise scenarios for rehabilitation of a single upper limb. Exercises within the same spatial area: (**a**) abduction movement of the limb, (**b**) parallel transfer of an object, (**c**) limb extension movement. Within the opposite spatial area: (**d**) parallel transfer of an object, (**e**) elbow flexion movement, (**f**) limb extension movement.  
Additionally, many of the object manipulation tasks are accompanied by a button press (see Figure 5), thereby increasing cognitive-motor integration and introducing an element of dual-task training.  
Depending on the programmed task sequence within a given exercise scenario, different degrees of joint motion are engaged.  
These motions follow the standards defined by the International Society of Biomechanics (ISB) [102].