Assistive device equipment can improve the performance of sit-to-stand (STS), standing, and walking of people with lower limb disability. The motorized assistive device is usually expensive and the use of another assistive device also makes an excessive force in the upper and lower extremity during (STS) transfer, which is not desirable for patients. In addition, only a few number of the non-motorized assistive devices that support all three phases; namely, sit-to-stand, standing, and walking are available. Consequently, improving and creating the new technology seems essential in this case. In this paper, the design procedure of saddle-assistive device is described in order to make use of the linear actuator in (STS) transfer and walk. Experimental results orientation of the shoulder during (STS) was recorded in the lab. Then, based on this analysis and simulation, saddle-assistive devices(S-AD) were designed and prototyped. Function prototype of the (S-AD) was done in the lab on a healthy person in (STS) and walking and then was compared with (STS) in normal mode. It is proposed due to the integration of the three phases in one device. Other advantages are force reduction on lower limbs, creating conditions of stability, and independence for patients with lower limb disability. Manuscript profile