**5. Nonstandard Steering System Designs and Related Certification and Driving License Examination Issues**

Universal design and "custom design" necessarily require a re-evaluation of many issues related to the certification of new solutions and obtaining driving licenses. The problem becomes particularly complex when we consider that there is a breakthrough in road vehicle technology. It is primarily about introducing vehicles with various levels of automation (according to the SAE classification), including vehicles at various levels of autonomy. According to the authors, the issues analyzed in this paper can be of great help here. Below is an outline of the solutions based on three-layer diagrams. The basic assumptions for their creation can be formulated in the following points:


Custom steering system designs increase the number of active users by adapting interface devices to the needs and limitations of drivers who are not fully able-bodied. This is possible if the vehicle is equipped with additional systems, such as drive by wire. The purpose of integrated design is, on the one hand, to provide a custom solution that is so intuitive and simple that it can be used by people with different constraints, while at the same time, there is some scope for individual customization. However, this requires close cooperation of designers with the vehicle end users in the design process. The next necessary stage is training with the use of the proposed interface solutions. Each driver would be given a diagram that defines the driver's rights. It would also be the same as the exam that was conducted. An example diagram is shown in Figure 16.

**Figure 16.** The concept of three-layer diagrams defining the driving license for a road vehicle.

Layer I in the case given in Figure 16 concerns the SAE classification. It can be seen how important it is to adopt the same (common on a global scale) classification. The work carried out, for example, under the UNECE World Forum for Harmonization of Vehicle Regulations (WP.29) on the regulation and harmonization of road regulations is of paramount importance here. Layer II, which will be developed along with the enhancement of new techniques, should include, among others, the type of steering system and additional equipment required. For example, in the case of steering the vehicle with brain waves, it is necessary to equip the cabin with screens that separate the driver's cabin from external electromagnetic interference. Layer III, on the other hand, contains a description of the disability. This list can be expanded and supervised by legal regulations. Figure 16 illustrates the following case:

The diagram concerns a person with a disability of the lower limbs (layer III). The driver can use a multifunction steering wheel or joystick. Additionally, the vehicle must be equipped with a drive by wire system. The driver is authorized to drive automation level 2, 3, or 4 according to the SAE classification. Level 5 means complete autonomy and will not have an interface (steering wheel) that would allow the driver to interfere with driving the car. The vehicle can only accept the trip's destination.

The above proposal should be considered as initially outlined. A number of additional problems should be taken into account when introducing it, e.g., how to eliminate the impact of the so-called simulator disease for research carried out on dynamic car simulators.

#### **6. Conclusions**

Providing people with various motor or sensory limitations with the possibility to drive vehicles will allow them to be more active in their social life and more independent.

The current practice consists of adapting the vehicle to the needs of a given person, using solutions available on the market that best suit the driver with a given disability. Nevertheless, the choice of the device does not always allow for efficient and easy steering. There is a need to search for solutions that are universal on the one hand and, on the other hand, still have a certain range of possibilities for individual adjustment. As part of the Eco-Mobility project, when designing a universal eco-car, it was equipped with a multifunctional steering wheel, which was anthropometrically verified, i.e., dimensioned to 95% of users. Only in experimental tests in a car simulator was it possible to evaluate the functionality of the new solution. The research was carried out on a sample of 30 men who did not have any motor limitations and who use standard steering wheels on a daily basis. The planned further tests will concern people using active wheelchairs, but as mentioned, it will require radical changes to the simulator's cabin in order to locate the wheelchair in it. Healthy drivers have specific driving habits and the short time spent on familiarizing themselves with the new steering wheel was not enough for them to feel its "sensitivity/responsiveness". In the case of people with disabilities of the lower limbs, there are usually also motor limitations of the upper limbs and, above all, the fingers. A smaller range of rotation of the ECO steering wheel and, at the same time, less movement of the limbs, in their case, may be an advantage and a positive feature of this solution.

The analysis of the test results showed the influence of the multifunction steering wheel parameters on the quality of maneuvers and the load on the driver's muscles. The obtained values of the adopted indicators confirmed a significantly lower functionality of ECO steering wheels in relation to the standard steering wheel in the "route" test. In the case of the "slalom" test, no statistically significant differences were found between the distributions of random variables of the paired observations. It can be assumed that the proposed solution of the multifunction steering wheel was not suited to the group of able-bodied drivers. Therefore, it seems that the thesis about the necessity to adapt the steering system to the individual characteristics of the driver is correct, in particular when it concerns people with reduced mobility. It can be obtained by integrating universal design and "custom design". This direction in the design process seems to be the only right one, as drivers with disabilities cannot use the standard steering system in most cases. On the other hand, the proposed solutions, apart from their reliability and safety, should minimize the stigmatization of users, i.e., they should be intended for all drivers with the possibility of minor improvements in special cases.

The development of the automotive industry, including the introduction of drive by wire technology, and the progressive automation of vehicles (partial autonomy) create completely new perspectives. In this case, the problem is also testing new solutions and granting permits to drive vehicles (in particular in relation to people with reduced mobility). Therefore, measures are taken to develop new rules for training drivers depending on the level of automation in the driven car. The three-layer diagrams proposed by the authors seem to be one of the interesting proposals defining the configuration of the steering system and the required skills obtained, for example, during training courses allowing driving at a specific level of automation and with an adapted steering system.

**Author Contributions:** Conceptualization, I.G., M.K. and W.C.; data curation, I.G.; formal analysis, M.K.; funding acquisition, W.C.; investigation, I.G., M.K. and W.C.; methodology, I.G., M.K. and W.C.; project administration, W.C.; resources, I.G. and W.C.; software, M.K. and W.C.; supervision, W.C.; validation, I.G., M.K. and W.C.; visualization, I.G. and M.K.; writing—original draft, I.G., M.K. and W.C.; writing—review and editing, I.G. and M.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** European Regional Development Fund: Eco Mobility Project (UND-POIG.01.03.01-14-154).

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics and Bioethics Committee Cardinal Stefan Wyszy ´nski University in Warsaw (KEiB–6/2015).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.
