About 74 million of the world population needs assistive leg devices on daily basis on account of some form of disability. Although the standard wheelchairs perform well on level ground terrains but they prove ineffective on soft ground and in crossing large obstacles. For dealing with the advance challenges of navigating the human environment a biped walker seems to a more suitable choice. The research presented here is focused on building and actuating a two-joint leg structure that is an integral part of ongoing leg-chair project in Popovic Labs. The project provides a proof of concept that how the synthetic hydro muscles (also developed by Popovic Labs) can be used for the control of large artificial limb joints. Here we discuss the designing, testing and corresponding refining of electronics design, actuation and control of the bi-joint hydro muscle actuated leg structure .We will also elaborate on the requirements, design, problems and refinement of some of the important mechanical components like Coupler/Decoupler and Force Multipliers.