First Results of a Study on the Vibrations Transmitted to the Driver by an Electric Vehicle for Disabled People During Transfer to a Farm

Abstract

This study evaluates the safety aspects of a prototype electric vehicle designed to enable wheelchair users to independently perform simple farm tasks in rural settings, like sample collection and crop monitoring. The vehicle, built at CREA, features four in-wheel electric motors, a pneumatic suspension system, and a secure wheelchair anchoring system. Tests at the CREA experimental farm assessed the vehicle’s whole-body vibrations on different surfaces (asphalt, headland, dirt road) using two tyre models and multiple speeds. A triaxial accelerometer on the wheelchair seat measured vibrations, which were analysed in accordance with ISO standards. Frequency analysis revealed significant vibrations in the 2–40 Hz range, with the Z-axis consistently showing the highest accelerations, which increased with the speed. Tyre A generally induced higher vibrations than Tyre B, likely due to the tread design. At high speeds, the effective accelerations exceeded safety thresholds on asphalt and headland. Statistical analysis confirmed speed as the dominant factor, with the surface type also playing a key role—headland generated the highest vibrations, followed by dirt road and asphalt. The results of these first tests highlighted the high potential of the vehicle to improve the agricultural mobility of disabled people, granting safety conditions and low vibration levels on all terrains at speeds up to 10 km h⁻¹. At higher speeds, however, the vibration levels may exceed the exposure limits, depending on the irregularities of the terrain and the tyre model. Overcoming these limitations is achievable through the optimization of the suspensions and tyres and will be the subject of the next step of this study. This technology could also support wheelchair users in construction, natural parks, and urban mobility.

1. Introduction

The agricultural sector in Italy offers significant employment opportunities for disabled individuals, but their integration is often hindered by the inability of the individual to operate machinery, insufficient support systems, and the lack of specialized equipment. Social farming initiatives aim to promote inclusion by providing work opportunities in agriculture. However, physical limitations and safety concerns make operating agricultural machinery particularly challenging. While modifications can improve the accessibility of this work, they may also introduce risks for both operators and co-workers [1].

Adapting machinery through ergonomic modifications, assistive technologies, and inclusive design can enhance the mobility, safety, and independence of individuals who are disabled in agricultural work. The Italian Decree of 17 January 2005 [2], issued by the Ministry of Infrastructure and Transport, permits disabled individuals to operate agricultural machines if they are properly adapted, highlighting the importance of mobility for workplace reintegration [3]. Despite these advancements, operators remain exposed to physical agents such as mechanical vibrations, which can impact their health and safety. Addressing these challenges through innovative solutions is essential to fostering greater accessibility and inclusion in agriculture.

In this context, in addition to the technical performance of the machinery the aspect of the protection of the operator’s health against accidents and occupational diseases has become increasingly relevant, which has led to the introduction of a series of devices and measures aimed at improving working conditions, such as sound-proof cabins to protect the driver from the noise emitted by the engine, transmission, and exhaust gas pipe [4,5] or increasingly effective shock-absorbing driving seats to protect against the vibrations induced by agricultural operations [6]. Vibrations certainly represent one of the most important and complex aspects to address, being generated by the characteristics and interaction of elements such as the tyres, axles, chassis, cabin and shock-absorbing seat itself. In modern tractors, high-frequency vibrations have a lesser importance in terms of health since seat suspensions are commonly effective in reducing them. Conversely, the interaction between the propulsion components (tyres and tracks) and the ground, especially during transit on compact surfaces and at high speeds, generates low-frequency vibrations, which cause by far the greatest discomfort and damage to the operator [7,8,9]. The Community Directive 2002/44/CE [10], establishing maximum values for the vibration exposure of workers (including those employed in the agricultural sector), has placed manufacturers of vehicles, machines, and equipment in front of a problem that is not yet completely resolved, namely the high generation of vibrations that, in the workplace (in practice the driving position), often far exceed the foreseen limits. However, it is necessary to consider that the norm, based on the criterion of daily exposure to vibrations, is certainly valid for the industrial sector but is objectively difficult to apply in the agricultural sector, where work is characterized by a seasonal trend and has peaks depending on factors such as crop and/or biological cycles, meteorological conditions, etc. Tyres can play an important role in the transmission of low-frequency vibrations to the driving position. The technical evolution of the treads together with suitable setting of the tyre inflation pressure can contribute, nowadays, to significantly reducing the vibration levels during transfers in fields and on other surfaces. For example, the increase in the section width (even over 700–800 mm for high-power tractors) and the decrease in the typical inflation pressure values (1 bar and even less) of tyres have simultaneously led to a significant increase in their contact area with the ground, which has the advantage of absorbing roughness and irregularities of the surface. In relation to these aspects, innovative vibration dampening systems have been developed which can be applied at the seat, cabin, and/or front axle level. Title VIII of Legislative Decree 81/08 defines the measures aimed at protecting the health of operators exposed to physical agents (including vibrations) [11]. However, drivers of agricultural vehicles often remain seated at the steering wheel for many hours, undergoing vibration levels three times higher than those that can be tolerated at the wheel of a car for the same exposure time [12]. The consequences of long periods of exposure to said levels of vibration can be important [13], as they can cause premature aging of the vertebral discs and the insurgence of professional’s diseases on the spine, like sciatica, lumbago, and herniated discs. Vibrations are initially absorbed by the tyres which act as an interface between the ground and the tractor, then propagate through the tractor frame, the cabin, and the driver seat and reach the body of the driver [14]. The role of the equipment is therefore crucial to limiting the body’s exposure to vibrations: the tyres, any suspensions, e.g., at the front axle and/or the cabin [15,16], and the suspended seat are the main devices for reducing them. The quality and type of the tyres have a direct impact on the level of vibrations to which operators are exposed, and it is therefore very important to adapt tractor equipment to the type of work that it will be used to carry out most frequently, to adjust the pressure to reduce vibrations, and, if possible, to use low-pressure tyres that have a much higher shock absorption capacity than cheap or low-end tyres. In this context, the reintegration of disabled people into productive activities in the agricultural sector would certainly be facilitated by increased mobility, which must however take place in compliance with safety conditions to improve the quality of their lives [17,18,19].

For these reasons, INAIL, through the BRIC 2019 call, promoted and financed the MOBI.RU.D. project (Rural Mobility for Disabled Persons), a research project aimed at developing an electric traction vehicle that is specially designed to promote and facilitate the insertion and/or reintegration of disabled people into the workplace, allowing them to move independently (without the use of the lower limbs) within rural sites and agricultural farms, in compliance with the legislation in force regarding the protection of the health and safety of the operators of agricultural equipment. A prototype of this vehicle was built at CREA. It enables the driver to get on board directly on their wheelchair, to fix it to the platform, and to start driving. As the vehicle can move on different surfaces, the driver can carry out various activities throughout a farm, such as direct monitoring of the status of crops or taking samples. The prototype has a frame that is open laterally on both sides so that an operator on a wheelchair will have direct access to the driving position. This aspect represents an important factor of serenity for the operator, who does not have to separate from his wheelchair. In the development of the prototype, it was necessary to take into account the aspects of the safety and health of the driver which were discussed above. This paper reports the following: (1) a description of the developed prototype; (2) the results of the first tests it was subjected to on asphalt, headland, and dirt road using two tyre models with different characteristics; (3) the evaluation of the conditions of safety and health with particular attention being given to the exposure of the driver to whole-body vibrations. The research scheme is summarised in Figure 1.

The test results indicated that the vehicle effectively enables the mobility of wheelchair users through good accessibility, anchoring, and manoeuvrability. The levels of whole-body vibration exceeded the limit value in some cases, especially during transfers at higher speeds on all test surfaces.

2. Materials and Methods

The tests of the prototype were carried out at the CREA farmland (Monterotondo, Italy, 42°5′51.26′′ N; 12°37′3.52′′ E; 24 m a.s.l.) with the aim of evaluating the behaviour of the prototype with regard to its capability to move on different surfaces while ensuring good safety/health conditions for the wheel-chaired driver. Considering that the vehicle is operated by an electric engine and the consequent absence of significant noise sources, whole-body vibration transmitted to the driver during travelling represents the main factor affecting the safety/health of the operator. Therefore, the tests concerned the evaluation of the levels of vibration depending on the variation in the following factors:

• The tyre model: two tyre models were mounted on the prototype;
• The ground surface: the tests were carried out on asphalt, headland, and dirt road;
• The travel speed: various speeds were adopted on each surface.

All tests were performed by the same driver, a person of about 80 kg sitting in his own wheelchair which was anchored to the vehicle structure.

2.1. The Prototype of Electric Vehicle

The prototype has been developed to allow the mobility of people on wheelchairs for a more general purpose of recovering them to an active/productive life in the agricultural sector. From this point of view, its main characteristics had to be the following:

• To give the possibility of accessing the driving place of the vehicle directly without transferring from the wheelchair to a conventional driver’s seat;
• To securely fix the wheelchair to the floor of the vehicle so as to allow the disabled person to drive it safely without being affected by the jolts due to irregularities in the road surface;
• To facilitate the driving and control operations of the vehicle and ensure safe conditions.

As for the type of propulsion, the electric solution was chosen, which is more sustainable both from an environmental point of view and from that of driver comfort due to the absence of exhaust gases and noise emissions.

2.1.1. Electric Powering and Control System of the Prototype

Figure 2 reports a schematic representation of the powertrain of the prototype.

The vehicle is equipped with four permanent magnet wheel hub motors of the “QS Motor” type 205 45H V3 2000 W, with a rated power of 2000 W (

Table 1. Specifications of QS motors 205 45H V3 2000 W hub motor.

Electric Motors	Height	244 mm
	Length	244 mm
	Width	275 mm
	Mass	13 kg
	Rated voltage	48 V DC
	Rated power (48 V)	2000 W
	Max speed (48 V)	494 rpm
	Max torque (48 V)	149 Nm
Power Supply System (Battery Pack)	Winston Cells	type LiFePO4
	Cell current	100 Ah
	Cell rated voltage	3.2 V
	Number of cells	15 (in series)
	Battery pack total voltage	48 V
	Battery pack total mass	49.5 kg
	Battery pack total volume	30 dm3

). Each motor is controlled by a dedicated inverter.

The electric motors are powered by a battery pack formed by 15 LiFePO4 Winston cells (Figure 3). The main characteristics of the power system are reported in Table 1. The charge status of each individual cell of the battery pack is controlled by the battery management system (BMS), which, through the vehicle management unit (VMU), informs the driver of the residual charge status by providing the residual distance (km) that the electric vehicle can still travel.

2.1.2. Chassis

The chassis was designed to be light, to ensure safety conditions, and to facilitate access by the wheelchaired driver. Therefore, the track width and the centre of gravity of the vehicle were suitably sized to avoid the overturning and to support the driving platform at a reduced height from the ground. The configuration of a standard frame was parametrized in terms of the positions and lengths of the most important structural elements and implemented to accommodate a wheelchair in total safety (Figure 4). The solution provides double access from both sides of the quadricycle via two ramps, a turntable, which has a maximum supportable load of 150 kg and a diameter of 420 mm, a platform large enough to accommodate a wheelchair, and an anchoring system to keep the wheelchair itself safe.

2.1.3. Suspension System

A pneumatic suspension system was adopted which is made up of four air bellows, in which the internal air pressure can be varied; four shock absorbers; an electric compressor, which keeps the air in the circuit under pressure; 4 switches, to inflate/deflate the bellows individually; and 4 control pressure gauges (Figure 5). Such a system, beyond shock absorption, allows the operator to vary the height of the vehicle from the ground and, in particular, to lower the quadricycle to facilitate access by the wheelchair by means of an ascent ramp of not-too-high dimensions and weight.

Considering the normal distance of the platform from the ground, which is approximately 110 mm, this solution allows it to be lowered by approximately 90 mm, i.e., until it is 20 mm from the ground (Figure 6). The horizontal platform visible in Figure 6a,b is 65 cm wide. It is fitted with a foldable, 35 cm wide extension which, if required by soil conditions, can be opened to reach the ground surface, further facilitating wheelchair access.

Table 2. Main characteristics of the prototype.

Masses	Total, kg	800	Battery pack included
	Battery pack, kg	375
	Max. transportable mass, kg	>300
	Max. platform capacity, kg	>300
Dimensions	Height, mm	1600
	Length, mm	2200
	Width, mm	1400	Closed platform
		2050	Open platform
		2400	Open platform extended
Others	Traction	4 WD
	Steering system	4 WS	Electronically controlled
	Turning radius, m	2.5	Four-wheel steering
	Tyre size, m	165/70 R14
	Maximum speed, km h−1	20	Limited
	Driving autonomy, km	70	Urban cycle
		40	Rural envir., frequent restarts
Steering aids	Accelerator	Wireless, trigger-operated
	Brake/handbrake	Manual push-forward lever
	Power assisted steering

reports the main characteristics of the prototype of an electric vehicle designed to be driven by people in wheelchairs.

Figure 7 shows a drawing of the prototype and how it has been realized, together with a particular view of the access system that is suitable for an operator on a wheelchair.

2.2. Tyre Models

Two new models of tyres were used in the tests. Both the front and rear tyres had the same size, i.e., 165 70R14. The first model was a Ziarelli Mud Power—M+S (Tyre A, Figure 8a,b), which is suitable for extreme driving conditions with mud or sand and is characterized by a deeply sculpted tread with large blocks (equippable with non-slip nails) and a central stepped groove that favours the lateral flow of water, mud, and sand.

The second model, Sava Eskimo S3+ (Tyre B, Figure 8c,d), is a winter tyre designed to ensure high grip and braking performance on wet and snowy surfaces, as well as at low temperatures. Both models were tested at an inflation pressure of 220 kPa in compliance with the requirements of the European Tyre and Rim Technical Organisation (ETRTO) [20].

2.3. Test Surface and Travel Speed

The chosen test routes are representative of the normal road network of the farm and, therefore, include asphalt roads, headlands, and dirt roads. The whole-body accelerations transmitted to the driver on the wheelchair were measured at various speed values. These varied with the surface, as reported in

Table 3. Travel speed values adopted by the “Mobirud” on the three test surfaces.

Test Surface	Travel Speed, km h−1
Asphalt	-	10	-	20	30
Headland	5	10	15	-	-
Dirt Road	-	10	-	20	-

. For each combination of tyre, surface, and speed, three replicates were carried out. In total, the test is composed of 48 replicates.

2.4. Measurement of Vibrations

The vibrations were measured by means of the instrumental chain shown in Figure 9, which is in compliance with the standards ISO 2631-1:1997 [21] and ISO 8041-1:2017 [22]: Soundbook, eight-channel system fitted with the software Samurai 1.7, for acquisition and processing of vibration data; PCB triaxial accelerometer, model SEN027, for driver seats; PCB calibrator, model 394C06 for accelerometers.

All measurements were carried out while taking care to verify that the measurements of the calibrated signals obtained by the accelerometer before and after the test did not exceed the limits specified in the standard ISO 16063-1:1998/Amd 1:2016 [23]. For each test thesis, three repetitions were performed using a sampling time of 60 s, which is sufficient to characterize the daily exposure of an operator to vibration risk. During the tests, the accelerometer was fixed on the driver seat with the axes oriented as shown in Figure 9, as required by the standards ISO 2631-1:1997 and ISO 5348:2021 [24].

The linear axial accelerations, a_x, a_y, and a_z, were measured simultaneously and analysed in frequency bands of ¹/₃ of an octave in the range 0.5–200 Hz. The instant linear accelerations were corrected according to the standard ISO 2631-1:1997/Amd 1:2010 and the D. Lgs. 81/08, within the frequency range 0.5–80 Hz, to obtain the weighted axial accelerations, a_wki. The weighting filter W_d was applied to the x and y axes, while the weighting filter W_k was applied to z-axis to obtain the instant axial weighted accelerations at time, t, between two measurements. The axial frequency weighted accelerations result from the following relation:

$$a_{wki}={\left[{\displaystyle \frac{1}{T}}{{\displaystyle \int }}_0^T{a}_{wki}^2\left(t\right)dt\right]}^{{\displaystyle \frac{1}{2}}}$$

(1)

where:

• a_wki is the weighted acceleration on the k-th axis (k = X, Y or Z) in the i-th frequency band (1 ≤ i ≤ 23, where 23 is the number of frequency bands in the range 0.5–80 Hz) measured at t;
• T is the duration (s) of the measurement.

The root mean square of the frequency components of each axis, a_wk, is calculated by means of the following relation:

$$a_{wk}={\left[{{\displaystyle \sum }}_{i=1}^{23}{a}_{wki}^2\right]}^{{\displaystyle \frac{1}{2}}}$$

(2)

where:

• a_wk is the r.m.s. weighted acceleration on the k-th axis (k = X, Y or Z).

The acceleration vector a_v (i.e., the total acceleration acting on the operator’s whole body) can be calculate by multiplying a_wx, a_wy, and a_wz by their respective corrective coefficients, by means of the following relation:

$$a_v={(k_x^2{a}_{wx}^2+k_y^2{a}_{wy}^2+k_z^2{a}_{wz}^2)}^{{\displaystyle \frac{1}{2}}}$$

(3)

where:

• k_x, k_y, and k_z are the corrective coefficients established on the basis of the position assumed by the operator when they are exposed to vibrations: in the case of a sitting position, we have k_x = k_y = 1.4 and k_z = 1.

The evaluation of the daily exposure over eight working hours is carried out by adopting an equal energy principle. The maximum exposure time, T_max, of an operator to a measured level of vibration can be calculated by means of the following relation:

$$A\left(8\right)=a_v.\sqrt{{\displaystyle \frac{T_{max}}{T_0}}}$$

(4)

where:

• A(8) is the weighted equivalent acceleration and represents an indicator of the level of vibration that the operator can be exposed to during the reference time, T₀. A(8) varies depending on the level of caution adopted. In Italy, the D. Lgs 81/08 (Title VIII, Physical Agents, Chapter III, Protection of workers from the risks of exposure to vibrations) establishes the following maximum levels of weighted acceleration values allowed for 8 h of work:
• Limit value: A(8) = a_lim < 1 m s⁻²;
• Action value: A(8) = a_act = 0.5 m s⁻²;
• T₀ is the reference exposure time corresponding to 8 h of work;
• T_max is the maximum time of exposure to a_v and varies depending on the value of A(8) that is adopted. It is calculated by making the formula explicit with respect to T_max.

Relation (4) is applied in all cases in which the values of at least two axial components (a_wk) are comparable. Conversely, when the solicitations mainly occur on one axis and make its component significantly higher than those of the other two, the formula is modified by replacing a_v with the highest a_wk.

2.5. Data Analysis

Direct noise measurements were used for the frequency analysis of linear axial accelerations, which are reported in diagrams to visualize any differences between the tyres, speeds, and surfaces. The linear axial accelerations were processed as explained in Section 2.4. in order to obtain the weighted axial accelerations a_wx, a_wy, and a_wz, the acceleration vectors a_v, and the maximum exposure times T_max. The evaluation of the vibrations was completed using the instantaneous peaks of the weighted axial accelerations needed to calculate the crest factor (CF) and verify any presence of impulsive vibrations when CF < 9, as stated in the abovementioned ISO 2631-1:1997/Amd 1:2010. Eventually, we conducted ANOVA and post-hoc tests on the dataset, by means of the software R 4.4.1, to verify the significance of the differences due to tyre models, speed values, and their interaction.

3. Results and Discussion

3.1. Test Results

All tests were carried out on the same day and the two tyre models were under similar environmental conditions. The overall distance that the tyres covered was less than 5 km and did not suffice to cause significant tyre wear or affect the vibration level. Moreover, the test sequence was the same for the two tyre models so, if any tyre wear occurred, it would occur in the same way in both models, ensuring the correctness of the comparison between them. Figure 10, Figure 11 and Figure 12 show the curves of the frequency analysis of the linear and weighted accelerations, respectively, measured on asphalt, headland, and dirt road with Tyre A and Tyre B at the speed values reported in Table 3. In general, significant levels of vibration were observed in the frequency interval 2–40 Hz. Here, the effects of the application of the weighting filters W_d and W_k mentioned in Section 2.4 are evident, with reduced peaks of Z components being observed mainly at higher speeds, and with flattened curves of X and Y components also being seen, both of which indicate that the Z components are the dominant ones.

The higher accelerations always occurred on the Z axis and the differences between the Z axis and the X and Y components increase with the travel speed on all surfaces. The maximum linear acceleration was a_z = 0.96 m s⁻² and was observed on asphalt, at 3.2 Hz, with Tyre A, at 30 km h⁻¹ (Figure 10a), and the corresponding weighted value (Figure 10b) was a_wz = 0.78 m s⁻². Both values are higher than those observed with Tyre B in the same conditions (a_z = 0.62 m s⁻² and a_wz = 0.50 m s⁻²). Conversely, still on asphalt, both at 20 and 10 km h⁻¹, the highest accelerations were produced by Tyre B, although the differences between Tyre B and Tyre A were very small at this point.

On headland (Figure 11) and dirt road (Figure 12), the higher Z accelerations were always observed with Tyre A, while no significant differences appeared when comparing the X and Y components of the two tyre models. Therefore, with the exception of Asphalt at 20 and 10 km h⁻¹, tyre A was always responsible for higher levels of vibration. This behaviour probably depended on how the large blocks of its tread interacted, at various speeds, with each test surface. From this point of view, at high speed (30 km h⁻¹), the production of vibrations could mainly be a consequence of the contact between the tyre’s big blocks and the smooth and hard surface of the asphalt road, while, on the same surface but at lower speeds, the tread’s blocks could have the time to deform and to act as shock-absorbers. On the other surfaces, despite the even lower speeds, this cushioning action could be overwhelmed by the combined action of the tread’s blocks and soil unevenness, which, again, would make Tyre A worse from the point of view of vibration.

The data shown in the diagrams of Figure 10, Figure 11 and Figure 12 were processed according to the procedure described in Section 2.4 in order to calculate the significant parameters needed to assess the driver’s exposure to whole-body vibration:

• The root mean square of the frequency band axial accelerations (a_wx, a_wy, a_wz), resulting from Relation (2);
• The acceleration vector (a_v), resulting from Relation (3);
• The maximum exposure time (T_max), resulting from Relation (4) and referring to the limit value (a_lim = 1 m s⁻²) and action value (a_act = 0.5 m s⁻²).

The results of the elaboration are reported in

Table 4. Tests of Tyres A and B on asphalt: values of weighted axial accelerations (a_wx, a_wy, a_wz), resultant vector (a_v), and maximum exposure time, T_max, are not to exceed, respectively, the limit value (a_lim < 1 m s⁻²) or the action value (a_act = 0.5 m s⁻²). The effective weighted accelerations are reported in bold characters.

Speed km h−1	Repl. St. Ind.	Tyre A						Tyre B
		awx	awy	awz	av	alim < 1 m s−2	aact = 0.5 m s−2	awx	awy	awz	av	alim < 1 m s−2	aact = 0.5 m s−2
		m s−2				Tmax (h)		m s−2				Tmax (h)
30	1	0.22	0.28	1.48	1.57	3.63	0.92	0.18	0.31	1.03	1.15	7.50	1.87
	2	0.24	0.31	1.56	1.66	3.27	0.82	0.16	0.23	0.92	1.00	9.38	2.35
	3	0.22	0.34	1.57	1.67	3.22	0.80	0.19	0.29	1.04	1.15	7.45	1.87
	Aver.	0.23	0.31	1.54	1.63	3.37	0.84	0.17	0.27	1.00	1.06	8.11	2.03
	St.D.	0.01	0.03	0.05	0.06	-	-	0.02	0.04	0.09	0.10	-	-
	C.V.	3.45	9.55	3.25	3.55	-	-	9.14	13.24	9.70	9.87	-	-
	St. Er.	0.00	0.02	0.03	0.03	-	-	0.01	0.02	0.05	0.06	-	-
20	1	0.16	0.18	0.62	0.71	<12	5.17	0.13	0.17	0.63	0.69	<12	5.10
	2	0.16	0.17	0.61	0.70	<12	5.28	0.13	0.19	0.64	0.71	<12	4.97
	3	0.16	0.17	0.65	0.73	<12	4.78	0.15	0.26	0.81	0.91	<12	3.03
	Aver.	0.16	0.18	0.63	0.71	<12	5.08	0.15	0.21	0.69	0.81	<12	4.37
	St.D.	0.00	0.00	0.02	0.01	-	-	0.02	0.05	0.10	0.12	-	-
	C.V.	0.35	2.34	2.70	2.10	-	-	16.60	21.19	14.38	15.35	-	-
	St. Er.	0.00	0.00	0.01	0.01	-	-	0.01	0.03	0.06	0.07	-	-
10	1	0.12	0.12	0.33	0.41	<12	<12	0.08	0.15	0.47	0.53	<12	9.10
	2	0.12	0.11	0.31	0.38	<12	<12	0.10	0.21	0.58	0.66	<12	5.95
	3	0.11	0.13	0.37	0.44	<12	<12	0.11	0.20	0.58	0.66	<12	5.97
	Aver.	0.12	0.12	0.34	0.41	<12	<12	0.10	0.18	0.54	0.62	<12	7.01
	St.D.	0.01	0.01	0.03	0.03	-	-	0.02	0.03	0.06	0.08	-	-
	C.V.	5.28	8.10	8.87	6.79	-	-	15.56	16.42	11.78	12.70	-	-
	St. Er.	0.00	0.01	0.02	0.02	-	-	0.01	0.02	0.04	0.05	-	-

,

Table 5. Tests of Tyres A and B on headland: values of weighted axial accelerations (a_wx, a_wy, a_wz), resultant vector (a_v), and maximum exposure time, T_max, are not to exceed, respectively, the limit value (a_lim < 1 m s⁻²) or the action value (a_act = 0.5 m s⁻²). The effective weighted accelerations are reported in bold characters.

Speed km h−1	Repl. St. Ind.	Tyre A						Tyre B
		awx	awy	awz	av	alim < 1 m s−2	aact = 0.5 m s−2	awx	awy	awz	av	alim < 1 m s−2	aact = 0.5 m s−2
		m s−2				Tmax (h)		m s−2				Tmax (h)
15	1	0.20	0.37	1.19	1.33	5.60	1.40	0.19	0.30	0.94	1.07	9.03	2.27
	2	0.25	0.41	1.44	1.59	3.85	0.97	0.19	0.32	1.05	1.18	7.23	1.80
	3	0.25	0.43	1.48	1.63	3.67	0.92	0.21	0.31	1.03	1.16	7.48	1.87
	Aver.	0.23	0.40	1.37	1.52	4.37	1.09	0.20	0.31	1.01	1.13	7.92	1.98
	St.D.	0.03	0.03	0.15	0.16	-	-	0.01	0.01	0.06	0.06	-	-
	C.V.	12.75	7.13	11.20	10.67	-	-	6.31	3.24	5.90	5.24	-	-
	St. Er.	0.02	0.02	0.09	0.09	-	-	0.01	0.01	0.03	0.03	-	-
10	1	0.20	0.29	1.04	1.15	7.43	1.87	0.16	0.26	0.72	0.84	<12	3.85
	2	0.18	0.28	0.95	1.05	8.93	2.23	0.14	0.21	0.62	0.72	<12	5.22
	3	0.20	0.33	0.99	1.12	8.23	2.05	0.12	0.20	0.64	0.71	<12	4.92
	Aver.	0.20	0.30	0.99	1.11	8.20	2.05	0.14	0.22	0.66	0.76	<12	4.66
	St.D.	0.01	0.03	0.05	0.05	-	-	0.02	0.03	0.05	0.07	-	-
	C.V.	6.62	9.39	4.61	4.57	-	-	15.73	15.43	8.09	9.50	-	-
	St. Er.	0.01	0.02	0.03	0.03	-	-	0.01	0.02	0.03	0.04	-	-
5	1	0.11	0.18	0.53	0.60	<12	7.20	0.08	0.14	0.43	0.48	<12	11.02
	2	0.11	0.16	0.46	0.53	<12	9.58	0.10	0.21	0.43	0.54	<12	10.62
	3	0.10	0.15	0.48	0.54	<12	8.83	0.10	0.18	0.45	0.54	<12	9.75
	Aver.	0.11	0.16	0.49	0.56	<12	8.54	0.09	0.18	0.44	0.52	<12	10.46
	St.D.	0.00	0.02	0.04	0.04	-	-	0.01	0.02	0.02	0.04	-	-
	C.V.	4.02	10.77	7.44	7.25	-	-	11.48	11.11	4.55	7.69	-	-
	St. Er.	0.00	0.01	0.02	0.02	-	-	0.01	0.01	0.01	0.02	-	-

, and

Table 6. Tests of Tyres A and B on dirt road: values of weighted axial accelerations (a_wx, a_wy, a_wz), resultant vector (a_v), and maximum exposure time, T_max, are not to exceed, respectively, the limit value (a_lim < 1 m s⁻²) or the action value (a_act = 0.5 m s⁻²). The effective weighted accelerations are reported in bold characters.

Speed km h−1	Repl. St. Ind.	Tyre A						Tyre B
		awx	awy	awz	av	alim < 1 m s−2	aact = 0.5 m s−2	awx	awy	awz	av	alim < 1 m s−2	aact = 0.5 m s−2
		m s−2				Tmax (h)		m s−2				Tmax (h)
20	1	0.18	0.19	0.94	1.01	9.02	2.25	0.13	0.17	0.74	0.80	<12	3.00
	2	0.16	0.23	0.92	1.00	9.37	2.35	0.14	0.20	0.83	0.90	11.00	2.00
	3	0.21	0.27	0.93	0.73	9.18	2.30	0.14	0.18	0.82	0.88	11.00	2.00
	Aver.	0.18	0.23	0.93	0.91	9.19	2.30	0.14	0.19	0.80	0.86	11.00	2.33
	St.D.	0.03	0.04	0.01	0.16	-	-	0.01	0.02	0.05	0.06	-	-
	C.V.	15.70	18.38	0.96	17.68	-	-	6.34	8.33	6.70	6.61	-	-
	St.Er.	0.02	0.02	0.01	0.09	-	-	0.00	0.01	0.03	0.03	-	-
10	1	0.12	0.15	0.59	0.65	<12	5.67	0.07	0.11	0.44	0.48	<12	10.00
	2	0.11	0.13	0.54	0.59	<12	6.88	0.09	0.13	0.49	0.54	<12	8.00
	3	0.12	0.14	0.56	0.62	<12	6.32	0.08	0.13	0.52	0.56	<12	7.00
	Aver.	0.12	0.14	0.57	0.62	<12	6.29	0.08	0.12	0.49	0.53	<12	8.33
	St.D.	0.01	0.01	0.03	0.03	-	-	0.01	0.01	0.04	0.05	-	-
	C.V.	4.66	7.39	4.90	5.04	-	-	8.61	9.85	8.65	8.58	-	-
	St.Er.	0.00	0.01	0.02	0.02	-	-	0.00	0.01	0.02	0.03	-	-

, respectively, for asphalt, headland, and dirt road and confirm the previous considerations regarding both the behaviour of the two tyre models and the clear prevalence, in all cases, of the Z component compared to the X and Y components, whose contribution in determining the value of a_v is very limited. The values of a_v are in fact always very close to those of a_wz, which were therefore taken into consideration as the effective accelerations in the calculation of the maximum exposure times. If we consider the averages of three replicates, the limit value was exceeded by the effective accelerations with both tyre models on asphalt at 30 km h⁻¹ (Table 4) and on headland at 15 km h⁻¹ (Table 3). The values of a_wz were between the limit value and the action values in all other cases except for Tyre A on asphalt at 10 km h⁻¹ (Table 4), both tyres on headland at 5 km h⁻¹ (Table 5), and Tyre B on dirt road at 10 km h⁻¹ (Table 6). However, sometimes, when the average values were slightly lower than the limit value or the action value, these limits were exceeded by the a_wz values of one or two replicates. In general, the results indicate that, at high speeds, Tyre B performs better than Tyre A, with a_wz values that are only slightly above the limit value. At lower speeds, the a_wz values of Tyre B, although never exceeding the limit value, were slightly higher than those of Tyre A on asphalt and lower than those of Tyre A on the other surfaces.

Table 7. Peak values of axial accelerations (a_wpeak) and crest factor, CF = a_wpeak/a_wz, where a_wz is the effective weighted accelerations whose values are reported in bold characters in Table 2, Table 3 and Table 4.

Surface	Speed km h−1	Rep.	Tyre A						Tyre B
			X		Y		Z		X		Y		Z
			awpeak	CF	awpeak	CF	awpeak	CF	awpeak	CF	awpeak	CF	awpeak	CF
			m s−2	-	m s−2	-	m s−2	-	m s−2	-	m s−2	-	m s−2	-
Asphalt	30	1	1.51	6.27	1.22	4.07	7.49	5.19	1.10	5.99	1.10	3.85	4.41	4.43
		2	1.29	5.88	1.08	3.66	9.69	6.53	0.71	4.44	0.86	3.41	4.47	4.96
		3	1.26	5.73	1.47	4.44	9.29	6.23	1.14	6.17	0.95	3.40	4.93	4.98
	20	1	0.81	5.69	0.87	4.97	2.85	4.67	0.60	4.92	0.84	5.01	3.18	5.27
		2	0.79	5.33	0.93	5.47	2.89	4.92	0.81	6.40	0.83	4.28	2.96	4.82
		3	0.87	5.44	0.80	4.66	2.33	3.82	0.77	5.44	1.65	6.90	4.34	5.64
	10	1	0.61	5.28	0.43	3.73	1.69	5.29	0.36	4.38	0.67	4.41	2.47	5.49
		2	0.35	3.12	0.52	4.91	1.28	4.31	0.69	6.92	1.09	5.33	3.87	7.07
		3	0.45	4.08	0.56	4.38	1.35	3.86	0.66	6.13	1.02	5.35	3.30	5.98
Headland	15	1	0.95	4.86	1.86	4.92	4.43	3.85	0.81	4.29	1.10	3.67	3.72	4.10
		2	0.91	3.73	1.54	3.81	5.60	4.02	1.51	7.25	2.13	6.03	6.51	6.16
		3	1.02	4.24	1.41	3.30	5.09	3.63	0.81	4.12	1.11	3.72	4.92	4.95
	10	1	0.73	3.75	1.06	3.76	3.90	3.90	0.56	3.77	1.11	4.54	2.90	4.13
		2	0.65	3.65	1.22	4.51	3.79	4.14	0.53	4.00	0.83	3.98	2.38	4.07
		3	1.14	5.76	2.27	6.87	4.98	5.20	0.43	3.69	0.63	3.21	2.49	4.05
	5	1	0.53	5.13	0.84	4.96	1.82	3.63	0.36	4.11	0.60	4.33	1.70	4.14
		2	0.61	5.74	0.73	4.63	1.93	4.40	0.37	3.60	0.94	4.73	1.76	4.24
		3	0.61	6.15	0.51	3.60	2.52	5.33	0.46	4.58	0.64	3.62	2.68	6.21
Dirt Road	20	1	1.12	6.48	0.83	4.17	6.25	6.91	0.70	5.66	0.74	4.18	3.63	5.10
		2	0.80	5.39	1.57	6.83	5.87	6.64	0.87	6.26	0.80	4.00	4.15	5.04
		3	0.84	3.92	1.14	4.17	3.80	4.16	0.89	6.33	1.14	6.00	4.72	5.89
	10	1	0.63	5.60	0.78	5.27	2.65	4.66	0.27	3.93	0.48	4.63	2.04	4.82
		2	0.46	4.17	0.57	4.35	2.33	4.45	0.55	6.37	0.51	4.02	2.01	4.21
		3	0.71	6.30	0.81	5.98	2.50	4.67	0.32	4.10	0.50	4.19	2.43	4.78

reports the peaks of instant weighted axial accelerations together with the values of the crest factor (C.F.). In this case, in all replicates, the maximum peak values and C.F. values occurred on the Z axis. Regarding the comparison between the C.F. of Tyre A and that of Tyre B, their values have a trend similar to the trend of the axial weighted accelerations on the three test surfaces, reported in Table 4, Table 5 and Table 6. However, since the C.F. values are always lower than 9, the presence of impulsive accelerations can be excluded.

3.2. Statistical Analysis

The statistical analysis of the results of the measurements confirmed the above considerations. The analysis was carried out on the value of a_wz that are reported in Table 4, Table 5 and Table 6. The series of values underwent the Shapiro–Wilk test and always resulted in normal distribution, except for two cases: (1) asphalt, speed 30 km h⁻¹, Tyre B, Repl. 2 (p = 0.026); (2) dirt road, speed 20 km h⁻¹, Tyre A, Repl. 3 (p = 0.029). The deviations in the values that caused the two negative responses to the Shapiro-Wilk test were not such as to make them be considered outliers (the mean and median were similar in both cases), so it was decided to submit the dataset to ANOVA.

The ANOVA (

Table 8. Results of the ANOVA carried out on the three datasets relating to the three test surfaces. Significance codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05.

Surface	Factors of Variation	Df	Sum Sq.	Mean Sq.	F Value	Pr (>F)	Signif.	Effect Size (η2)
Asphalt	Replic.	2	0.026	0.013	-	-	-
	Tyre	1	0.036	0.036	9.04	0.013	*	0.06
	Speed	2	2.333	1.166	293.88	1.31 × 10−9	***	0.39
	Tyre:Speed	2	0.459	0.230	57.83	3.19 × 10−6	***	0.55
	Residuals	10	0.040	0.004	-	-	-
Headland	Replic.	2	0.002	0.001	-	-	-
	Tyre	1	0.320	0.320	40.22	8.44 × 10−5	***	0.37
	Speed	2	1.923	0.962	120.79	9.92 × 10−8	***	0.06
	Tyre:speed	2	0.095	0.047	5.94	0.020	*	0.57
	Residuals	10	0.080	0.008	-	-	-
Dirt Road	Replic.	2	0.007	0.004	-	-	-
	Tyre	1	0.016	0.016	1.70	0.240	-	0.37
	Speed	1	0.295	0.295	30.77	0.001	**	0.11
	Tyre:speed	1	0.001	0.001	0.13	0.733	-	0.51
	Residuals	6	0.058	0.010	-	-	-

) indicated the speed as the most significant factor affecting the levels of vibration on all surfaces (asphalt and headland: 0 < p < 0.001; dirt road: 0.001 < p < 0.01), while, for the tyre model, we observed a lower significance on asphalt (0.01 < p < 0.05), a high significance on headland (0 < p < 0.001), and no significance on dirt road (0.1 < p < 1). The differences due to the interaction between the tyre and speed were highly significant on asphalt, (0 < p < 0.001), less significant on headland (0.01 < p < 0.05), and not significant on dirt road (0.1 < p < 1). The values of η² reported in Table 8 confirm that the effect size of the speed is strongly related to the tyre model, highlighting the importance of the interaction between the two factors. The effect of the tyre model slightly increases on dirt road.

Table 9. Results of the Tukey test carried out on the asphalt dataset, based on the results of the ANOVA reported in Table 8. Cases with no significance are in italics.

Factors of Variab.	Pairwise Compar.	Diff.	lwr	upr	p Adj.
Tyre	B-A-0.0	−0.0893	−0.1652	0.0134	0.0249
Speed	v20-v10	0.2265	0.1127	0.3403	5.039−4
	v30-v10	0.8513	0.7374	0.9651	0
	v30-v20	0.6248	0.5110	0.7386	0
Interaction Tyre:Speed	A:v30-A:v10	1.2202	1.0175	1.4229	0
	A:v30-B:v10	1.0156	0.8129	1.2183	0
	A:v30-A:v20	0.9218	0.7191	1.1245	0
	A:v30-B:v20	0.8610	0.6583	1.0637	1.00−7
	B:v30-A:v10	0.6870	0.4843	0.8896	1.00−6
	B:v30-A:v30	−0.5332	−0.7359	−0.3305	1.560−5
	B:v30-B:v10	0.4823	0.2797	0.6850	4.360−5
	B:v30-A:v20	0.3886	0.1859	0.5913	3.569−4
	B:v20-A:v10	0.3592	0.1565	0.5619	7.317−4
	B:v30-B:v20	0.3278	0.1251	0.5304	0.0016
	A:v20-A:v10	0.2984	0.0957	0.5011	0.0035
	B:v10-A:v10	0.2046	0.0019	0.4073	0.0474
	B:v20-B:v10	0.1546	−0.0481	0.3573	0.1808
	A:v20-B:v10	0.0938	−0.1089	0.2965	0.6398
	B:v20-A:v20	0.0608	−0.1419	0.2635	0.9066

,

Table 10. Results of the Tukey test carried out on the headland dataset, based on the results of the ANOVA reported in Table 8. Cases with no significance are in italics.

Factors of Variab.	Pairwise Compar.	Diff.	lwr	upr	p Adj.
Tyre	B−A	−0.2667	−0.3515	−0.1820	1.7600 × 10−5
Speed	v15−v10	0.3931	0.2660	0.5203	7.60−6
	v5−v10	−0.4075	−0.5347	−0.2804	5.30−6
	v5−v15	−0.8006	−0.9278	−0.6735	0
Interaction Tyre:Speed	B:v5−A:v15	−1.0243	−1.2507	−0.7979	0
	A:v5−A:v15	−0.9617	−1.1881	−0.7353	1.00−7
	A:v15−B:v10	0.7619	0.5355	0.9883	1.10−6
	B:v5−B:v15	−0.6395	−0.8659	−0.4131	7.40−6
	B:v5−A:v10	−0.6152	−0.8416	−0.3888	1.110−5
	A:v5−B:v15	−0.5769	−0.8033	−0.3505	2.170−5
	A:v5−A:v10	−0.5526	−0.7790	−0.3262	3.370−5
	A:v15−A:v10	0.4092	0.1828	0.6356	0.0006
	B:v15−A:v15	−0.3849	−0.6113	−0.1585	0.0011
	B:v15−B:v10	0.3770	0.1507	0.6034	0.0013
	B:v10−A:v10	−0.3528	−0.5792	−0.1264	0.0022
	B:v5−B:v10	−0.2624	−0.4888	−0.0360	0.0203
	A:v5−B:v10	−0.1998	−0.4262	0.0266	0.0959
	B:v5−A:v5	−0.0626	−0.2890	0.1638	0.9313
	B:v15−A:v10	0.0243	−0.2021	0.2507	0.9990

and

Table 11. Results of the Tukey test carried out on the dirt road dataset, based on the results of the ANOVA reported in Table 8. Cases with no significance are in italics.

Factors of Var.	Pairwise Compar.	Diff.	lwr	upr	p Adj.
Tyre	B−A	−0.0737	−0.1934029	0.0459	0.193
Speed	v20−v10	0.3135	0.1938	0.4332	3.09–4
Interaction Tyre:Speed	A:v20−B:v10	0.3872	0.1522	0.6223	3.32–3
	B:v20−B:v10	0.3337	0.0987	0.5687	0.0081
	A:v20−A:v10	0.2933	0.0583	0.5283	0.0167
	B:v20−A:v10	0.2398	0.0048	0.4748	0.0456
	B:v10−A:v10	−0.0939	−0.3290	0.1411	0.5988
	B:v20−A:v20	−0.0535	−0.2885	0.1815	0.8827

report the results of the post-hoc test relating to the data shown in Table 8. In particular, the Tukey pairwise test for equal means showed highly significant differences between the vibration levels for all speed values on all surfaces. As to the interaction between the tyre and speed, the Tukey pairwise test regarded all possible combinations of factors (15 comparisons on asphalt and headland; 6 comparisons on dirt road). In Table 9, Table 10 and Table 11, the cases of no-significance are reported in italics. For each comparison, the tables also report the lower and upper observed values and the difference between the means. The differences between the means for Tyres B and A were always negative on all surfaces, indicating that Tyre A causes a higher level of vibration than Tyre B. Similarly, for speed, observing the sign of the differences between the means shows that the level of vibration is always higher for higher speeds.

Eventually, the ANOVA test was carried out to assess any significant effects of the surfaces on the levels of vibration emitted by the two tyre models. In this case, the test only concerned the data observed at 10 km h⁻¹, which was the only speed value used on all three surfaces. The results of the analysis (

Table 12. Results of the ANOVA carried out on the dataset resulting from all data observed at 10 km h⁻¹ on the three surfaces. Significance codes: 0 ‘***’ 0.001 ‘*’ 0.05.

Factors of Var.	Df	Sum Sq.	Mean Sq.	F Value	Pr (>F)	Signif.	Effect Size (η2)
Replication	2	0.0027	0.00136	0.416	0.6706	−
Tyre	1	0.0293	0.02931	8.979	0.0134	*	0.08
Surface	2	0.6162	0.30811	94.402	3.22 × 10−7	***	0.36
Tyre:Surface	2	0.2334	0.11669	35.753	2.78 × 10−5	***	0.56
Residuals	10	0.0326	0.00326	−	−	−

) show a very high significance (0 < p < 0.001) of the differences due to the type of surface and the interaction between this and the tyre, and a lower significance (0.01 < p < 0.05) of the differences due to the tyre model. In this case, the effect size of the different factors’ variability on the total variability was very small for tyre models and increased for test surface and, mostly, for the interaction between surface and tyre model.

The results of the post-hoc test relating to the data shown in Table 12 confirm the results of the ANOVA (

Table 13. Results of the Tukey test related to the results of the ANOVA reported in Table 12.

Factors of Var.	Pairwise Compar.	Diff.	lwr	upr	p Adj.
Tyre	B−A	−0.08069842	−0.1364476	−0.02494923	0.0083147
Surface	DR−Asph.	0.0585	−0.0251	0.1421	1.9020 × 10−1
	HL−Asph.	0.4185	0.3349	0.5021	0
	HL−DR	0.3599	0.2763	0.4435	2.0 × 10−7
Interaction Tyre:Surface	A:HL−A:Asph.	0.6972	0.5483	0.8460	0
	A:HL−B:DR	0.5833	0.4344	0.7322	2.0−7
	A:HL−B:Asph.	0.4926	0.3437	0.6414	1.30−6
	A:HL−A:DR	0.4893	0.3405	0.6382	1.40−6
	B:HL−A:HL	−0.3528	−0.5016	−0.2039	4.550−5
	B:HL−A:Asph.	0.3444	0.1955	0.4933	5.790−5
	B:HL−B:DR	0.2305	0.0817	0.3794	2.341−3
	A:DR−A:Asph.	0.2078	0.0590	0.3567	0.0054
	B:Asph.−A:Asph.	0.2046	0.0557	0.3535	0.0060
	B:HL−B:Asph.	0.1398	−0.0091	0.2887	0.0703
	B:HL−A:DR	0.1366	−0.0123	0.2854	0.0792
	B:DR−A:Asph.	0.1139	−0.0350	0.2627	0.1788
	B:DR−A:DR	−0.0939	−0.2428	0.0549	0.3393
	B:DR−B:Asph.	−0.0907	−0.2396	0.0581	0.3726
	A:DR−B:Asph.	0.0032	−0.1457	0.1521	1.0000

). Also, in this case, the differences between the means of Tyres B and A are negative, confirming that higher vibrations are caused by Tyre A on all surfaces at 10 km h⁻¹. As regards the effects of the surface, the significance of the difference between the means is always very high and, according to their values, higher vibration levels are observed on headland, followed by dirt road and asphalt.

4. Conclusions

The prototype of the electric vehicle developed for wheelchair users in this study effectively enables autonomous mobility in agricultural environments, allowing access and manoeuvrability without requiring a transfer from the wheelchair to the driver’s seat. Features such as the adjustable platform, pneumatic suspension, and secure anchoring system make it suitable for various agricultural tasks, including crop monitoring and sample collection. However, the significant vibrations that occur when moving over different surfaces remain a critical issue that could affect safety and health. One key limitation is the transmission of low-frequency vibrations to the operator’s body on uneven terrain, particularly due to tyre–ground interaction. The prototype performs quite well on all surfaces; however the level of vibration can exceed regulatory exposure limits, especially at high speeds and with certain tyres. The tests conducted herein indicated that the z-axis was the most affected by vibrations. The highest weighted accelerations were observed with Tyre A, with mean values of 1.54 m s⁻² and 1.37 m s⁻² on asphalt at 30 km h⁻¹ and on headland at 20 km h⁻¹, respectively. Since said values exceeded both the action value (0.5 m s²) and the limit value (1 m s²), the driver’s exposure times were significantly reduced compared to the theoretical 8 h: with regard to the limit value, the exposure times were 3.37 h on asphalt at 30 km h⁻¹ and 4.37 h on headland at 20 km h⁻¹. The exposure times referred to the action value were even lower (0.84 h and 1.09 h). Tyre B behaved better than Tyre A in all cases, with lower weighted accelerations which only touched the limit value in the two above mentioned cases, i.e., on asphalt at 30 km h⁻¹ and headland at 20 km h⁻¹. Enhancing the suspension system with advanced vibration damping technologies and testing specialized tyres could help mitigate this issue. Further improvements could focus on optimizing the suspension system, which could be based on a semi-active [25] or active [26] vibration control system fitted with hydraulic or electromagnetic actuators. Considering the results of the present and previous studies, the development of such new systems should mainly concern low frequency vibrations [27]. Further contribution to the reduction of vibrations could come from the adoption of low-pressure tyres that are more suitable for agricultural terrain and more capable of absorbing shocks due to soil unevenness. Expanding research into vibration reduction and operator safety and comfort, integrating IoT technologies for real-time monitoring, and implementing high-capacity batteries or hybrid traction could further improve the performance and sustainability of our prototype. Although designed for agriculture, the vehicle’s features make it easily adaptable to other sectors that are characterized by rough terrain, such as construction sites, natural parks, and urban areas with or without architectural barriers, and could also significantly upgrade urban mobility. In all cases, the electric vehicle would improve the quality of life of disabled people and support their re-integration into active life [28]. Such a fan of possible applications could have a positive economic impact, triggering innovative production activities and startups aimed at the industrial development of the vehicle and its diffusion and use in the form of sale or rental. Specific modifications could enhance its usability in diverse environments, improving mobility and employment opportunities for individuals with disabilities. In conclusion, the electric-powered vehicle prototype shows significant potential for development and broader application, but addressing the challenges related to vibrations and operator safety will be essential to expanding its usability in both rural and other professional settings.