Semipowered and unpowered enhancing prosthesis are very hard to actually implement. Here&#x27;s an ARS article about a lab actually succeeding: <a href="http:&#x2F;&#x2F;arstechnica.com&#x2F;science&#x2F;2015&#x2F;04&#x2F;an-unpowered-exoskeleton-decreases-the-energy-required-for-walking&#x2F;" rel="nofollow">http:&#x2F;&#x2F;arstechnica.com&#x2F;science&#x2F;2015&#x2F;04&#x2F;an-unpowered-exoskele...</a>