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

Abstract

<jats:title>Abstract</jats:title> <jats:p>This paper investigates the feasibility of replacing metal robot links by wooden bodies for the purpose of eco-sustainable design. 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. In this work, to be able 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. Experiments for characterizing its accuracy and its stiffness are performed. Experimental results show that it is realistic to design a wooden robot with performance compatible with Industry requirements in terms of stiffness (prototype deformations lower than 400 microns for 20 N loads) and accuracy (prototype repeatability lower than 60 microns), guaranteed in a rectangular workspace of 800 mm x 200 mm. These works provide a first step towards the eco-sustainable mechanical design of robots.</jats:p>