At least one exoskeleton system in order to provide walking support to people who have disability in walking or in order to provide performance improvement to healthy people, and having at least one first body for being connected to the motionless upper part of the leg and at least one second body for being connected to the motionless lower part of the leg and at least one knee embodiment provided between said first body and said second body in a manner allowing motion of the knee joint, and at least one leg embodiment for forming support to the foot part by being connected to the second body, wherein said knee embodiment comprises at least one crossed four-bar linkage provided in a manner supporting the bio-mechanical motion of the knee joint from the side (sagittal plane) part of the knee joint, said crossed four-bar linkage comprising: a first part connected to the first body, a second part connected to the second body, a third part connecting the first part and the second part, allowing motion compliant with the bio-mechanics of the knee joint, a movement element, wherein the movement element is associated with the first part from one end of the long edge and is associated with the second part from the other part thereof, an energy storage element connected to the movement element and a positioning element, wherein the positioning element is a support connected to the first body wherein the energy storage element provides support to the movement of the knee, the exoskeleton system further comprises; an activation housing allowing the energy storage element to move within the activation housing, wherein said activation housing is essentially a slot which will provide engagement and disengagement of the support, a locking element, said crossed four-bar linkage further comprises at least one spring, said spring being configured to be compressed during upward movement of the locking element when the heel touches the ground, and wherein, when the locking element passes to the high position, the spring fixes the position of the energy storage element and provides engagement thereof, such that during weight acceptance, the energy storage element realizes weight acceptance support by means of storing energy, and said spring also drives the locking element downwardly within the activation housing when the heel is elevated from the ground, thereby the locking element allows free movement of the energy storage element in the activation housing. a first part connected to the first body, a second part connected to the second body, a third part connecting the first part and the second part, allowing motion compliant with the bio-mechanics of the knee joint, a movement element, wherein the movement element is associated with the first part from one end of the long edge and is associated with the second part from the other part thereof, an energy storage element connected to the movement element and a positioning element, wherein the positioning element is a support connected to the first body wherein the energy storage element provides support to the movement of the knee, the exoskeleton system further comprises; an activation housing allowing the energy storage element to move within the activation housing, wherein said activation housing is essentially a slot which will provide engagement and disengagement of the support, a locking element, said crossed four-bar linkage further comprises at least one spring, said spring being configured to be compressed during upward movement of the locking element when the heel touches the ground, and wherein, when the locking element passes to the high position, the spring fixes the position of the energy storage element and provides engagement thereof, such that during weight acceptance, the energy storage element realizes weight acceptance support by means of storing energy, and said spring also drives the locking element downwardly within the activation housing when the heel is elevated from the ground, thereby the locking element allows free movement of the energy storage element in the activation housing.