## 1 Introduction  
Duchenne muscular dystrophy (DMD) is a disease that affects approximately 4.78 per 100.000 born male children [1, 2]. DMD is produced by an X-linked recessive dystrophy myopathy caused by the absence of _ dystrophin proteins_ in the muscular system, myocardium, and brain [3]. This pathology is characterized by muscular weakness that leads to early confinement in a wheelchair. Several complications may arise during the course of the disease such as irregular muscle fatigue, lack of stability during walking, and cardiac and respiratory complications, especially during adult ages [4]. A few years ago, DMD was considered a disease with zero treatment expectations; however, nowadays, there are methods used to slow down the natural evolution of the disease through early diagnosis and specialized treatments. These treatments include the use of corticosteroids such as prednisone and deflazacort [5], as well as gene and stem cells therapy [6]. One of the most effective treatments to slow down the muscular dystrophy evolution is physical therapy with muscular stretching and nutritional supplements to maintain symmetrical muscle mobility [7]. Physical therapy for individuals with DMD has been shown to be helpful in monitoring changes in strength, range of motion, and functional mobility. Additionally, it provides a tool for interventions in and education of individuals and their families on stretching,positioning, and activity pacing [8]. Nevertheless, providing constant and reliable therapy is a complex task due to the limited access to rehabilitation centers. This is a common problem for illnesses that require physical therapy. Nowadays, progress has been made to tackle this problem with an engineering perspective using exoskeletons to assist movement that improves functional walking ability [9]; however, the development of such tools for the treatment of DMD patients has been scarce. Applications of wearable arm exoskeletons have been developed for assisting patients with DMD and help them to improve their performance in the execution of daily life activities [10]. These applications allow for enhancing upper extremity function of DMD patients via robotic exoskeletons [11; 12; 13] However, less attention has been devoted to the development of exoskeletons for lower limb assistance or therapy. Consensus on the treatment of patients with DMD has pointed out that appropriate physical therapy could reduce the rate of progression of the disease [7]. These treatments should be formulated by a multidisciplinary team including neurologists, pediatrics, neurologists, and rehabilitators, which should adapt the therapy to the patient's stage of clinical progression. However, performing physical therapy according to medical recommendations could be challenging due to the lack of appropriate technological tools. The aims of treatment during the early DMD phases are devoted to maintaining a level of activities that preserves the ability to perform daily functions. In this way, to maintain muscle strength, the use of orthopedic devices such as knee-ankle-foot orthoses (KAFOs) could prolong the patients' independence and mobility [14]. The early stages of DMD are focused on preserving muscle extensibility and joint mobility and symmetry to prevent contractures and deformities [15]. To accomplish the objective of maintaining the muscles and joints' functionality, each patient should receive between four to six sessions of physical therapy per week [16]. However, achieving this high frequency of therapy is not feasible because of the limited medical personnel available at these therapy centers. This reveals the need for the development of technological tools that allow for preventive management of muscle flexibility and extensibility. Gait exoskeletons have been used to assist therapy of children that suffer cerebral paralysis [17] and spinal muscular atrophy. Atlas 2030 is a robotic system that supports patients from the trunk to the feet and provides mobility to lower limbs and trunk stability.