The ankle joint has an important role in human mobility, providing stability, flexibility and ability to support body weight, during daily and sports activities. Due to its constant functional demand, ankle injuries are very common among other musculoskeletal diseases, with high rates of recurrence when rehabilitation is insufficient. These injuries can lead to long-term functional limitations, reduced mobility and decreased quality of life, if not addressed effectively. The complexity of ankle biomechanics requires precise rehabilitation procedures to restore full functional capacity. Conventional rehabilitation methods require significant therapist involvement, are often repetitive and offer limited precision or adaptability. Robotic rehabilitation devices have become a viable approach, facilitating accurate execution of movement patterns, consistent training and progress monitoring. However, current systems often face limitations related to transportability, operational simplicity and patient engagement. In this two part paper we will propose three versions of “portable” rehabilitation devices. In the first part design considerations and structural configurations of three versions of ankle rehabilitation platforms are discussed, characterized by low cost, user-friendliness and two degrees of freedom, suitable for both clinical and home use.