# Systematic Review of Mecanum and Omni Wheel Technologies for Motor Impairments
## 1 Introduction  
Assistive technology includes diverse tools and systems aimed at supporting individuals with motor impairments in achieving greater independence. These solutions are crucial for facilitating daily activities and improving mobility. Research in this field is carried out from multiple perspectives, focusing on enhancing accessibility [1] and advancing functionality--particularly through the integration of robotics, artificial intelligence, and sensor-based systems, as demonstrated in smart wheelchair technologies [2]. Assistive mobility devices, especially powered wheelchairs, have progressively evolved to incorporate advanced control mechanisms and mechanical improvements. These developments aim to meet not only basic mobility needs but also the demands of complex environments, ensuring greater safety, adaptability, and user-specific customization [3]. Understanding wheelchair user behavior, anthropometric factors, and ergonomic workspace layouts is essential for maximizing performance, safety, and comfort [4]. Postural support, in particular, significantly affects physical activity and quality of life, underlining the importance of proper seating and positioning systems [5]. Wheelchair users frequently encounter difficulties navigating complex or confined environments, highlighting the need for more maneuverable and adaptive technologies. Inresponse to this demand, researchers and designers have increasingly turned their attention to innovative solutions that improve flexibility and ease of movement. Among these advancements, the Mecanum wheels--invented by [PERSON] in 1973 [6]--and omni wheels stand out as key technologies offering significant improvements in multidirectional mobility. Mecanum wheels have rollers mounted at a 45\({}^{\circ}\) angle around a cylindrical base, allowing for omnidirectional motion without changing the platform's orientation, which is particularly advantageous in confined or dynamic spaces such as urban or healthcare environments. However, their limited grip on uneven terrain necessitates advanced control algorithms. Omni wheels, on the other hand, have rollers positioned perpendicular to the wheel axis, making them easier to control and more affordable. They are ideal for lightweight or educational applications, although they support lower load capacities compared to Mecanum wheels [7] (Figure 1). Mecanum and omni wheels stand out as innovations that have found extensive applications in mobile robotics. For example, [PERSON] and [PERSON] [10] proposed a four-wheeled omnidirectional robot using steerable wheels, while [PERSON] and [PERSON] [11] focused on kinematic modeling and control strategies for such platforms. Similarly, [PERSON] et al. [12] investigated positioning errors in Mecanum-based mobile robots, and [PERSON] and [PERSON] [13] explored holonomic designs for manipulation tasks. [PERSON] et al. [14] provided a theoretical discussion on holonomy in mobile robots, further supporting the widespread adoption of these wheels in autonomous navigation. These technologies have also proven valuable in industrial applications. For instance, [PERSON] et al. [15] conducted a systematic survey of Mecanum wheel-based robotic systems used in production, logistics, and service automation. Despite their advantages, Mecanum and omni wheels have notable drawbacks, including vibration, instability, and poor shock absorption on uneven terrain or when crossing thresholds. These issues arise primarily from intermittent roller-ground contact, generating vertical vibrations that compromise stability and comfort. Various studies have explored strategies to mitigate these effects. [PERSON] et al. [16] optimized wheel design to minimize vertical oscillations by analyzing equivalent stiffness. [PERSON] et al. [17] examined contact forces on rollers to understand how design influences vibration behavior. Additionally, [PERSON] et al. [18] analyzed whole-body vibration in electric wheelchairs when transitioning between surfaces, providing real-world insights into comfort and safety.