This paper presents clinical results from the use of monitor-nomad (MONIMAD), which is a reactive robotized interface for lower limb rehabilitation of patients suffering from cerebellar disease. The first problem to be addressed is the postural analysis of sit-to-stand motion. Experiments with healthy subjects were performed for this purpose. Analysis of external forces shows that sit-to-stand transfer can be subdivided into several phases: preacceleration, acceleration, start rising, and rising. Observation of center of pressure, ground forces, and horizontal components force on handles yields rules that identify the stability of the patient and adjust the robotic interface motion to the human voluntary movement. These rules are used in a fuzzy-based controller implementation. The controller is validated on experiments with diseased patients at Bellan Hospital, Paris, France.