## 1 Introduction  
As life expectancy increases and fertility rates decrease, the proportion of the elderly population is growing significantly worldwide [1]. In South Korea, where population aging is progressing at the fastest pace in the world, the proportion aged 65 or older accounted for 17.5% in 2020 and is expected to increase to 46.4% in 2070 [2]. As the elderly's desire for quality of life increases along with such rapid population aging, various studies on age-friendly products that can provide quality services to the elderly are being conducted [3]. For the elderly, walking ability is an essential factor for carrying out daily life and social activities. However, when sensory function, postural reflexes, and muscle strength deteriorate due to physical aging, the elderly's gait strategy changes [4]. Walking assistance devices such as a came or walker are representative age-friendly products that provide psychological stability to the elderly who have difficulty walking normally and support safe activities by preventing falls [5]. Selecting an appropriate assist device is very important for walking safely in the elderly. It has been established that both the standard walker and wheeled walker (rollator), which can efficiently assist walking through extended supports, provide greater stability and mobility than canes [6]. Previous studies have compared and analyzed the differences between the two types of walkers in terms of biomechanics. [PERSON] al. [7] reported that the wheeled walkers, rather than standard walkers which require lifting the device off the ground when walking, can help elderly people with reduced upper body strength maintain a natural walking pattern. [PERSON] et al. [8] compared the clinical effectiveness of two types of walkers and found that using wheeled walkers was faster and involved less energy expenditure than standard walkers. In addition, postural stability in older adults with muscle weaknesses and balance impairments were improved by the use of a rollator [6]. In other words, it was confirmed that using a rollator, which enables smooth movement with less effort than a standard walker, is more suitable for the elderly. On the other hand, the use of walking aids can be a risk factor for falls in elderly people [5]. Additionally, it was reported that fall injuries occur mainly on uphill, downhill, uneven ground, and obstacle terrain [9]. Plantar pressure distribution and electromyography (EMG) measurements are widely used and useful clinical evaluation methods to evaluate foot load characteristics and lower extremity function during walking. In previous studies, the gait strategy of the elderly in various walking environments were investigated by analyzing biomechanical variables, including gait pattern, muscle activity, and plantar pressure. [PERSON] et al. [10] found that older adults' gait patterns were more variable during the initial stance phase and the middle swing phase to maintain stability and prevent falls when walking on uneven ground. [PERSON] et al. [11] revealed a walking strategy in the elderly that compensates for physical limitations by simultaneously activating lower extremity and pelvic muscles during forward propulsion during uphill walking. Based on analysis of lower limb muscle activity and plantar pressure, [PERSON] et al. [12] confirmed that the pressure and contact time of the rearfoot increase to prevent falls that may occur due to unstable ankle movement when elderly people walk in an outdoor environment. In recent years, with the development of technology, many studies related to intelligent wheeled walkers have been conducted. [PERSON] et al. [13] demonstrated the effectiveness of a robotic wheeled walker in improving gait and postural stability in patients with balance disorders. [PERSON] et al. [14] introduced a step detection algorithm for rollator users based on a three-axis accelerometer in smartwatches. [PERSON] et al.