Design of an Accurate and Stiff Wooden Industrial Robot: First Steps Toward Robot Eco-sustainable Mechanical Design

This article investigates the feasibility of replacing metal robot links by wooden bodies for eco-sustainable design's purpose. Wood is a material with low environmental impact and a good mass-to-stiffness ratio. However, it has significant dimensional and mechanical variabilities. This is an issue for industrial robots that must be accurate and stiff. To guarantee stiffness and accuracy performance of a wooden robot, we propose an integrated design process combining (i) proper wood selection, (ii) adequate sensor-based control strategies to ensure robot accuracy, and (iii) a robust design approach dealing with wood uncertainties. Based on the use of this integrated design process, a prototype of a wooden five-bar mechanism is designed and manufactured. Experimental results show that it is realistic to design a wooden robot with performance compatible with industry requirements in terms of stiffness (deformations lower than 400 mu m for 20 N loads) and accuracy (repeatability lower than 60 mu m), guaranteed in a workspace of 800 mm x 200 mm. This study provides a first step toward the eco-sustainable mechanical design of robots.