## 3 Results
### Testing Results and Discussion  
The data obtained from laboratory testing (two exemplary courses) are presented in Figures 28 and 29. It is visible that all the events were registered correctly, both in terms of position and force change. It is noteworthy that the registered forces with simulated usage are very low (not exceeding 4 N). However, no dynamic scenarios (such as hitting against hard objects or lifting a heavy weight) were considered at this point, so that was to be expected.  
The tests with the patient went without any disturbances, and the prosthesis worked as expected, and the patient was comfortable with it and was able to operate the vehicle  
Figure 28: Sample data collected during laboratory tests—course #1.  
Figure 29: Sample data collected during laboratory tests—course #2.  
without any problems. However, as compared with the mechanical version, it was observed by the patient and the researchers that the electronic parts (especially the force sensor beam and SD card reader) stick outside the prosthesis main shell and could interfere with the clothing (long sleeves). Also, proper covering would be needed to prevent damage to the electronics via unfavourable atmospheric conditions (such as rain or snow). Another issue might be the need to use and attach a power bank properly (e.g., at patient's belt or in pocket), which might pose problems with ergonomics. These design considerations will be taken into account in the next version of the prosthesis.  
The photographs of this testing phase are shown in Figures 30 and 31.  
The data were gathered properly, without any breaks and improper data points. The data plots were recorded from two static tests, and the dynamic test (ride) are presented in Figures 32-34.  
In Figures 32 and 33, it is clearly visible that the nature of realized movements was different, by analysing the IMU data, and they correspond closely with real observed movements. Also, the force sensor readings are compatible with the IMU data, i.e., moments when the patient encountered resistance of the handlebar and changed the direction of the movement are clearly identifiable.  
In Figure 34, the nature of the patient's movement can be also easily guessed from the Euler angles patterns recorded in the plot. The force changes also correspond closely with the movement. A single visible dip was a threshold that patient encountered in the middle of the test drive path.  
Figure 33: Data registered in static test #2—right–left movement.  
Figure 32: Data registered in static test #1—up–down movement.  
It can be observed that the registered force during the test drive is considerably higher than in any other test. However, it is still very low (not exceeding 10 N). As such, the use of prosthesis in that manner is completely safe. However, the conditions in the test were also \"safe\" asthe patient did not drive very fast (no faster than 10 km/h) and did not encounter any serious terrain obstacles or height differences that might have caused the higher forces to occur. Further tests and more results are needed, and the patient has been given a prosthesis, and the results will be gathered and used in other experiments by the authors.  
To sum up the results, it should be stated that the obtained sensor data represented the measured activity in an expected manner. The prosthesis has been evaluated successfully by obtaining positive feedback from the patient himself, also recording proper data with installed low-cost sensors, compliant with the observations. As such, its concept was approved, and initial prototype was assumed as ready for further implementation work. The prosthesis with its sensors can be considered as a successful prototype as the idea of low-cost personalized 3D printed bicycle prosthesis equipped with sensors for registering the course of driving was proven to be viable and will be continuously developed.