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Wood for the construction of robots

These robots are made of a special material: within the lightweighting research project InRoHo, robot structures are being built using wood-based materials. This can help to save resources, reduce CO₂ emissions, and create flexible, high-performance robot systems.

What does an industrial robot look like? Clear, complex, futuristic, with a lot of cables and knobs, and in any case made of metal. Or perhaps not? Most industrial robots are currently made of steel or aluminium. But the InRoHo lightweight construction research project shows that it is also possible to build industrial robots in a lightweight design and thus lighter, more environmentally friendly and just as high-performing.

Industrial robots are used for production automation or for the handling of workpieces in many sectors, e.g. in the automotive industry and in mechanical engineering. Today, the load-bearing structures of these articulated and jointed arm robots are typically made of aluminium or steel castings. While this ensures high stiffness, precision and load capacity, the production of such parts also requires a lot of energy and therefore results in high CO₂ emissions. The robots  made of these materials are also comparatively heavy.

^{Significant saving potential compared with metal robot structures}

Furthermore, the current manufacturing methods are economically viable only in case of large production volumes with standardised geometries. At the same time, demand is increasing for robots whose dimensions and reach can be adjusted to specific applications. Rigid modular designs and long development periods have so far made this customisation difficult.

Wood-based materials can serve as an alternative. Wood is a regenerative raw material and can thus store CO₂, it has great potential for lightweight construction and can be processed in a flexible manner using panels-based construction methods and computer-assisted production. So far, wood has seldom been used as load-bearing material for the construction of robots and machinery.

^{Wood as an innovative lightweight material for high-tech robotics}

The InRoHo research project therefore aims to develop industrial robots based on wood construction whose performance, precision and lifetime is similar to those of conventional metal-based robots, while being much lighter and offering a better carbon footprint. Another focus is being placed on economically viable production – also for small production series. For this purpose, the project team is developing a modular wood-based lightweight design which allows the flexible adjustment of payload, range and geometry to different applications. The project partners are ligenium GmbH (project coordinator), the Institute of Materials Handling, Conveying and Plastics Engineering of Chemnitz University of Technology and Siemens AG.

By replacing metallic structure components with the regenerative raw material of wood, the aim is to reduce greenhouse gas emissions in both production and operation. In the long term, it will thus be possible to develop new design principles for climate-friendly mechanical and plant engineering, which can also be applied to further machinery and plant components.

^{New design concept for robot structures made of wood}

In a first step, load-bearing robot components made from wood-based materials and wood-composite materials are being designed to withstand the forces and movements of an industrial robot. Wherever appropriate, the researchers are combining wood with other materials (hybrid construction) to enhance the stiffness, vibration damping and precision. In addition, simulation models are being built and tested to realistically predict the mechanical behaviour, vibration characteristics and the lifetime of the wood structures. This helps to evaluate designs in a targeted way before extensive tests are carried out. Furthermore, the team is drawing up lifecycle assessments and comparing the environmental impact of the wood-based robots with conventional robots made of metal.

In order to allow for the configuration of the robot arms for different reaches, geometries and applications, adaptable modular concepts are being developed and tested using demonstrators as to their industrial feasibility. The project team brings together expertise from lightweight construction, wood engineering, robotics and simulation.

The project, which has received €838,000 under the Technology Transfer Programme Lightweight Construction (TTP LB), will run until the end of September. It demonstrates impressively that the mitigation of climate change and industrial performance are not conflicting aims.