Electric personal mobility devices (EPAMDs) have become an integral part of modern transportation, offering convenient and eco-friendly alternatives to traditional vehicles. These devices, which include electric skateboards, kick scooters, self-balancing unicycles, and Segways, typically transport individuals at speeds up to 25 km/h (16 mph) and have found widespread adoption in urban environments [1][2]. Their rising popularity underscores the need for effective repair and maintenance, particularly focusing on battery management systems (BMS), motors, and other electrical components, to ensure their reliability and safety [3][4].

The core of EPAMDs’ functionality lies in their advanced battery systems and BMS. Proper estimation of key health indicators such as state of charge (SOC), state of health (SOH), and state of energy (SOE) is critical for optimal performance. This necessitates a thorough understanding of electrical circuits, components, and safety protocols among repair technicians [3][4]. Certification standards, like those provided by UL Solutions, ensure that these devices meet rigorous safety requirements, further emphasizing the importance of technical expertise in their upkeep [5].

Different regions classify and regulate EPAMDs in various ways, reflecting ongoing evolution in terminology and legislative frameworks. For example, in New Zealand, the Segway PT is categorized as a mobility device, similar to electric wheelchairs and mobility scooters, and must comply with specific usage rules [1]. This regional variability necessitates a nuanced understanding of local regulations for both users and repair technicians, adding another layer of complexity to the management and maintenance of these devices.

Despite their benefits, EPAMDs have not been without controversy. Public hire e-scooters, in particular, have been linked to a significant number of injuries, prompting debates about their safety and the need for stringent regulations [6]. These concerns highlight the critical role of well-trained technicians who can effectively troubleshoot and repair these devices, ensuring they operate safely and efficiently. Through proper maintenance and adherence to safety standards, the potential of EPAMDs to offer convenient, sustainable transportation solutions can be fully realized [6][2].

Overview

Electric personal mobility devices (EPAMDs) have become increasingly prevalent in modern transportation systems, including electric skateboards, kick scooters, self-balancing unicycles, and Segways. These devices typically transport individuals at speeds up to 25 km/h (16 mph) [1]. Their growing popularity has led to the necessity of integrating these devices into existing transportation policies to ensure safe operation and improve the safety of all road users [2].

The functionality of these devices heavily relies on the performance of their battery management systems (BMS). A BMS is essential for monitoring various health indicators (HIs) such as state of charge (SOC), state of health (SOH), state of energy (SOE), and state of power (SOP) [3]. Proper estimation of SOC is particularly crucial as it ensures optimal battery charging and discharging, thereby enhancing the device’s reliability and safety [3].

Repair technicians working on EPAMDs must possess a comprehensive understanding of electrical systems, including knowledge of electrical circuits, components, wiring, soldering, and safety protocols. This expertise is vital for diagnosing and repairing these vehicles efficiently and optimizing their performance [4]. In addition to understanding the electrical systems, technicians must be familiar with the specific testing and certification standards. For instance, UL Solutions is recognized by the Occupational Safety and Health Administration (OSHA) as a Nationally Recognized Testing Laboratory (NRTL) for certifying micromobility products to UL 2272 standards, covering the electrical systems of personal e-mobility devices [5].

Furthermore, the terminology and classifications for these devices continue to evolve. While terms like personal transporter, electric rideable, and personal mobility device are commonly used, the definitions and regulations surrounding these devices differ across regions [1]. For example, in New Zealand, the Segway PT is categorized as a mobility device, similar to mobility scooters or electric wheelchairs, and must adhere to specific usage rules [1].

Types of Electric Personal Mobility Devices

Mobility Scooters

Electric scooters are another prevalent form of personal mobility device, favored for their ease of use and efficiency. Typically, they include essential parts that facilitate smooth operation and maintenance. These scooters are particularly beneficial for individuals who find traditional mobility scooters too bulky or stigmatizing, offering a more modern and sporty design. Some models can achieve ranges up to 40 miles on a single charge and have features like electrically opened storage compartments and anti-theft systems[7].

Electric Wheelchairs

Electric wheelchairs, also known as power wheelchairs, are among the most popular types of medical mobility equipment worldwide. These devices provide significant independence for users, allowing them to travel longer distances with minimal effort. The evolution of electric wheelchairs has led to advanced models equipped with the latest technology, including Internet of Things (IoT) and Artificial Intelligence (AI), enabling features such as autonomous navigation and health monitoring[8][9]. Heavy-duty models are available for users who require higher weight capacities without sacrificing mobility, featuring customizable armrests and contoured seats for optimal comfort[10].

Segways and Personal Transporters

The Segway™ Human Transporter, introduced in the 1990s, is a notable innovation in the category of personal mobility devices. It is designed to aid individuals with disabilities in navigating longer distances more efficiently. Personal transporters, or powered transporters, encompass a variety of compact, motorized vehicles designed for individual use, such as electric skateboards, kick scooters, and self-balancing unicycles. These devices typically operate at speeds not exceeding 25 km/h (16 mph) and have been subject to various legislative classifications worldwide[11][1].

Advanced Manual Wheelchairs

While not electric, advanced manual wheelchairs have also seen significant technological improvements. These wheelchairs are designed to be extremely light and durable, with features that allow for customized ergonomic adjustments to enhance user comfort and efficiency. Although manual, these devices play a crucial role in providing mobility solutions for individuals who prefer or require a non-motorized option[8].

Historical Context

The development and use of electric personal mobility devices (ePMDs) are rooted in a long history of personal mobility solutions aimed at aiding those with reduced mobility. As early as 1733, William Kent created an early stroller[12], and by 1760, the invalid carriage, or Bath chair, had brought the technology into more widespread use[12]. The push scooter, an ancestor to many modern mobility devices, was invented by Denis Johnson in 1819 and was typically constructed from wood[12].

In the 1930s, advancements in manufacturing materials made strollers more affordable and widespread[12]. This period also saw the emergence of the first powered mobility devices. Electric personal assistive mobility devices (EPAMDs) began to gain traction as power-assisted solutions for those with partial or complete immobility[11]. Innovations such as the Segway™ Human Transporter have added to the versatility and convenience of these devices[11].

The evolution of mobility devices is closely tied to technological advancements and societal awareness of the needs of people with disabilities. Electric wheelchairs, for instance, have seen significant changes in the last decade, moving from roller or belt drives to back-geared motor drives, and from electric to electronic control systems, which offer various programming advantages[13]. As of recent estimates, there are approximately 160,000 users of electric-powered wheelchairs and scooters in the United States alone, with about 100,000 using wheelchairs and 60,000 using powered scooters[11].

Despite the benefits and growing adoption of ePMDs, their use has been controversial, primarily due to safety concerns. Public hire e-scooters, in particular, have been involved in a significant number of injury incidents, prompting discussions about regulations and safety measures[6]. Nonetheless, these devices provide a convenient, on-demand form of transport that can potentially alleviate traffic congestion and offer solutions for short trips and last-mile commutes[6].

The legal landscape for ePMDs is still evolving, with various countries and states implementing policies to regulate their use on roadways, walkways, and sidewalks[2]. This ongoing evolution in legislation and technology reflects the dynamic nature of personal mobility devices and their role in modern transportation systems.

Components and Functionality

Electric personal mobility devices consist of several key components that work together to ensure efficient operation. Understanding these components and their functionality is essential for anyone involved in the repair and maintenance of these devices.

Battery Systems

Lithium-Ion Batteries

Lithium-ion batteries are the most commonly used power source in electric personal mobility devices due to their high energy density and efficiency. They provide a high capacity, allowing devices to operate for extended periods without frequent recharging. However, these batteries come with certain limitations, including the need to maintain a specific charge range (typically between 15% to 85%) to prevent cell weakening and potential safety issues such as thermal runaway [14][15].

Nickel-Metal Hydride (NiMH) Batteries

NiMH batteries are another type of rechargeable battery used in some personal mobility devices. They have a lower energy density compared to lithium-ion batteries but offer higher specific energy and energy density than lead-acid batteries. NiMH batteries are known for their high cycle life and recyclability, making them a viable option for various applications [16].

Battery Management System (BMS)

A critical component in managing the battery’s health and performance is the Battery Management System (BMS). The BMS is responsible for monitoring and controlling the charging and discharging cycles of the battery cells. It ensures that the voltage, current, and temperature of any cell or module stay within defined safety limits to prevent potential hazards like thermal runaway [17][14].

The BMS also performs statistical, stress, and fault analyses to verify the reliability of the battery pack. Tools are available to generate models from basic datasheet specs and measurement curves, facilitating the design process and ensuring the battery’s safety and efficiency [17].

Electric Motors

Electric motors are the driving force behind personal mobility devices, converting electrical energy from the battery into mechanical energy to propel the vehicle. These motors are designed to be efficient and reliable, ensuring smooth operation over various terrains.

Control Systems

The control system in an electric personal mobility device manages the interaction between the user and the machine. It includes throttle controls, braking systems, and various sensors that monitor the device’s performance. Advanced control systems can also include features such as regenerative braking, which recovers energy during braking to extend the battery life.

Charging Systems

Charging systems are essential for maintaining the energy levels of the battery. These systems must be compatible with the specific battery type used in the device, whether lithium-ion or NiMH, to ensure efficient and safe charging. Proper maintenance of charging systems is crucial to prevent issues like overcharging or overheating [14][16].

Safety Features

Safety features in electric personal mobility devices include various sensors and protective mechanisms to ensure user safety. These features can range from thermal sensors that monitor the temperature of the battery and motor to automatic shutdown systems that activate in case of a malfunction. Ensuring these safety features are functional is a critical aspect of device maintenance [14][18].

Understanding these components and their functionality is crucial for anyone involved in the repair, maintenance, or design of electric personal mobility devices. Proper knowledge and training in these areas ensure the devices operate efficiently and safely.

Repair and Maintenance

Repair and maintenance of electric personal mobility devices, such as electric wheelchairs, scooters, and other similar vehicles, involve several key areas including component troubleshooting, battery management, and motor repairs.

Component Troubleshooting

Effective repair of electric personal mobility devices often begins with component-level troubleshooting. Technicians diagnose issues with both hardware and software components of these devices. Common problems include malfunctioning power systems, motors, and batteries. The troubleshooting process involves identifying malfunctioning components and replacing them as necessary, utilizing lead and lead-free soldering, board-level troubleshooting, and circuit analysis[19]. For example, a detailed cleaning and regular maintenance can prevent dirt, grime, bacteria, and mold accumulation, ensuring the optimal performance of mobility devices like power wheelchairs and electric scooters[20].

Battery Management System (BMS)

The battery management system (BMS) plays a crucial role in the operation and maintenance of electric personal mobility devices. The BMS is responsible for monitoring, controlling, and protecting battery packs. It performs functions such as thermal management, state estimation, and fault diagnosis. Key aspects of BMS management include ensuring battery safety by preventing overheating, short circuits, and overcharging or undercharging, which could lead to battery damage or safety hazards[21][14]. The BMS also provides status estimation of the battery’s capacity, health, and remaining life, which helps in determining the battery’s availability and performance[22][23].

Motor Repairs

Motor issues are a common problem in electric mobility devices. These devices typically use 24-volt motors, and problems can range from motor failure to performance degradation. Regular maintenance and timely replacement of motors are essential to keep the devices functioning properly[20]. Technicians specializing in electric mobility devices are equipped to perform motor replacements and other related repairs to ensure users regain mobility and independence swiftly[24].

General Troubleshooting and Maintenance

Maintaining electric personal mobility devices in top shape requires regular maintenance checks and timely troubleshooting. Users can follow troubleshooting guides to identify and resolve common issues such as battery and electrical problems, steering, and brake issues. Regular maintenance helps in early detection of potential problems, ensuring that the devices remain reliable and safe for daily use[25][26]. When complex issues arise, it is advisable to seek professional repair services to avoid further damage and ensure proper repairs are conducted[27].

By adhering to proper maintenance protocols and utilizing specialized repair services, users can ensure the longevity and optimal performance of their electric personal mobility devices.

Technical Knowledge and Training

Technical knowledge and training are pivotal for the maintenance and repair of electric personal mobility devices. A thorough understanding of electrical systems, including components, circuits, and wiring, is essential for diagnosing and resolving issues effectively. Key systems within these devices, such as the charging systems, battery systems, and high-voltage systems, require specific expertise to maintain and repair [4].

EV repair technicians must possess a comprehensive understanding of various subsystems, including the cooling system, power electronics converter, and high voltage interlock loop system. These components are crucial for the safe and efficient operation of electric vehicles. For instance, the cooling system protects the battery from overheating, while the power electronics converter allows the battery to provide power to the motor [4].

Training programs often focus on both theoretical and practical aspects, ensuring that technicians can handle complex electrical problems. This includes knowledge of electrical circuits, wiring, soldering, and adherence to safety protocols. Understanding these elements not only enables effective diagnosis and repair but also contributes to optimizing the vehicle’s performance [4].

Moreover, electric wheelchair troubleshooting involves both software and hardware analysis. Advanced troubleshooting techniques may require specialized tools or expertise and should ideally be conducted by trained professionals. This comprehensive training ensures that technicians can inspect and repair wheelchairs to ensure user safety and cost management [24].

Battery management systems (BMS) are another critical area of focus in training programs. Effective thermal management within a BMS is essential for maintaining optimal battery performance. Systems can utilize active liquid cooling, often employing ethylene-glycol coolant, to maintain the temperature across the battery pack assembly within a narrow range. This involves circulating coolant through a system of pumps, pipes, and heat exchangers [28][17]. Understanding these cooling techniques, including the trade-offs between pumping speed and thermal consistency, is crucial for technicians [28].