Rampco - Deliverable D2.2

The present deliverable "D2.2 Bill of materials, design documents, 3D simulations and physical prototype of traction system" describes in detail the final design of the traction system and the bill of materials (BOM) and presents the physical traction system prototype construction. The starting point for this deliverable is the previously prepared deliverable D2.1, which specified the design specifications, computations and 3D simulations. The traction system consists of two main units: The traction UNIT A (one part in each side) and the UNIT B balancing mechanism (one part in each side). In the following paragraphs the BOM and the construction of the UNIT A is first presented. Then the BOM and the construction of the UNIT A is presented. Details on components are provided in attachments at the end of the deliverable. The unit A is based on long tracks so to ensure multiple touching points on stair steps and to distribute the traction power over a larger friction surface. During the RampCo operation the teeth of the tracks will match the carpet profile. The track is directed around two main aluminum alloy pulleys, driven by pulleys from a very light and compact servo- gear-motor with the transmission of power between the gearbox and the traction wheel is realized by a double synchronous belt. The whole mechanism is hosted into two lightweight aluminum frames. The gearbox and belt transmission realize a non-back-drivable 40:1 transmission. The two Units B are responsible of keeping the platform horizontal. The counterbalancing function is based on the continuous rotation of servo motors either clockwise or counter-clockwise based on feedback from the inclinometer. The Units B consist of the frame and the actuator. The materials used for the construction are: Ergal Aluminum 7075 for the two legs, the two rods responsible for counterbalancing the platform and the wheels housing units, Carbon Fibre for the frame tubes and Aluminum 6061 for the external cylinder of the actuator, the tube connectors and the peripheral components required to provide the motion and power. During the final design an additional active, fail- safe electromagnetic brake is added that provides a locking mechanism effectively preventing unwanted behaviour in the case of a power failure or any failure in the motors/drivers/control system. The manufacturing processes applied for the construction of traction system are: CNC milling, CNC turning, conventional milling and turning, laser cutting, drilling, threading, boring and press fitting. Reported results have regularly been exchanged and discussed with all the partners during the periodic technical meetings (December 2014, March 2015) and web sessions.