# Cable-Driven Exoskeleton for Ankle Rehabilitation in Children with Cerebral Palsy
## 1 Introduction
This robotic gait orthosis is designed for intensive locomotion therapy and features actuated hip and knee joints that guide the user's legs along predefined trajectories while walking on a treadmill. The system includes a dynamic body weight support (BWS) mechanism that gradually reduces support as the patient progresses, allowing for a more natural gait pattern [14]. By combining robotic assistance with a treadmill, Lokomat enables high-repetition, task-specific gait training under controlled conditions, optimizing movement patterns while reducing the physical strain on therapists [15]. Additionally, the system provides real-time biofeedback through a visual interface, enhancing patient engagement and motor learning. Studies have demonstrated significant improvements in gait speed, balance, and walking endurance, particularly in patients with neurological impairments such as stroke and CP. However, while Lokomat training enhances locomotion parameters, its effects on functional independence and overground walking ability remain comparable to those of conventional physiotherapy, highlighting the need for individualized rehabilitation approaches [16]. Despite demonstrating a positive impact for gait rehabilitation scenarios, these robotic devices are rigid and heavy structures that limit the subject's freedom of movement and, in some cases, introduce significant inertia in their joints [17]. For this reason, in recent years, exosuits have been developed as lighter structures that are better adapted to the patient's morphology compared with rigid exoskeletons. In exosuits, weight support relies entirely on the patient and their skeletal structure, reducing the device's weight and minimizing movement restrictions through the use of fabric harnesses and low-profile actuation systems [18]. Exosuits tend to sacrifice some efficiency in power transmission to the user in exchange for greater comfort, allowing for prolonged use, reducing the inertia introduced by rigid exoskeletons on the human body, and improving metabolic efficiency [19]. One of the main examples of exosuits is the ReStore (ReWalk Robotics, Israel). It is designed as a robotic lower-limb exoskeleton that assists locomotion by providing support for hip and knee flexion and extension, enabling individuals with spinal cord injuries, post-stroke hemiplegia, and other mobility impairments to walk with assistance [20]. In addition to supporting walking, ReWalk allows users to transition between sitting, standing, and walking postures, enhancing its functional applicability in rehabilitation settings [21]. Studies have demonstrated its effectiveness in improving mobility and post-stroke rehabilitation, as well as its ability to reduce the metabolic cost of walking, making ambulation more efficient for users [20]. Furthermore, research on the ReWalk ReStore exosuit confirms its safety, reliability, and clinical feasibility in post-stroke rehabilitation, with a reduction in adverse events following individualized device adjustments and training [20]. A multi-site clinical trial demonstrated that, after just 5 days of training with the ReStore, participants significantly increased both their assisted and unassisted walking speeds, highlighting its potential to enhance gait recovery [22]. While exosuits offer a novel and promising direction in assistive rehabilitation, they are fundamentally limited by their reliance on wearable interfaces for force transmission. These systems require continuous and secure physical contact with the user's body to actuate motion effectively, which can compromise comfort, restrict natural movement, and hinder voluntary motor exploration. As an alternative, exoskeletons based on Cable-Driven Parallel Robots (CDPRs) have emerged to address these limitations. Unlike wearable exosuits, CDPR systems externalize actuation by using lightweight cables to apply forces remotely, minimizing the mechanical load on the user.