Emerald Group Publishing Limited
Copyright © 2011, Emerald Group Publishing Limited
Focus on efficiency: bird flight deciphered
Article Type: Mini features From: Industrial Robot: An International Journal, Volume 38, Issue 6
One highlight for visitors at the 2011 Hanover Trade Fair was to see the fascinating SmartBird (Figure 1) in flight. One of the oldest dreams of mankind is to fly like a bird – to move freely through the air in all dimensions and to take a “bird’s-eye view” of the world from a distance. No less fascinating is bird flight itself. Birds achieve lift and remain airborne using only the muscle power of their wings, with which they generate the necessary thrust to overcome the air resistance and set their bodies in motion – without any rotating “components”. Nature has ingeniously achieved the functional integration of lift and propulsion. Birds measure, control and regulate their motion through the air continuously and fully autonomously in order merely to survive. For this purpose, they use their sensory organs.
The flight of birds was long shrouded in mystery. Many scientists failed in their attempts to understand how birds fly, and the secret remained unsolved. The research team from the family-owned enterprise Festo has now, in 2011, succeeded in unravelling the mystery. The key to its understanding is a unique movement that distinguishes SmartBird from all previous mechanical flapping wing constructions and allows the ultra-lightweight, powerful flight model to take off, fly and land autonomously.
SmartBird flies, glides and sails through the air just like its real-life counterpart – the herring gull – with no additional drive mechanism. Its wings not only beat up and down, but also twist at specific angles. This is made possible by an active articulated torsional drive unit, which in combination with a complex control system makes for unprecedented efficiency in flight operation. Festo has thus succeeded for the first time in attaining an energy-efficient technical adaptation of this model from nature.
In developing the model, the engineers were able to draw on their wealth of experience and innovations. The experience gained with the Bionic Learning projects AirRay and AirPenguin was incorporated into the creation of SmartBird. The fascination of building an artificial bird that could take off, fly and land by means of flapping wings alone provided the inspiration for the development team: as a global player in pneumatics, Festo’s mastery of airflow is unparalleled. In the development and production of the latest generations of cylinders and valves, the objective is to make optimal, efficient use of airflow for automation technology.
An unusual feature of SmartBird is the active torsion of its wings and the fact that it dispenses with the use of additional lift devices. The aim of the SmartBird project was to achieve an overall structure that is efficient in terms of resource and energy consumption, with minimal overall weight, in conjunction with functional integration of propulsion and lift in the wings and a flight control unit in the torso and tail regions. Further requirements were excellent aerodynamics, high-power density for propulsion, and maximum agility for the flying craft. The outcome is an intelligent biomechatronic overall system.
In practice, this system operates above all in an energy-efficient manner: the propulsion and lift, as intended, are achieved solely by the flapping of the wings and have a power requirement of only around 23 W. SmartBird has a total weight of around 450 g and a wingspan of 2 m. Measurements have demonstrated an electromechanical efficiency factor of around 45 per cent and an aerodynamic efficiency factor of up to 80 per cent. SmartBird is thus an excellent example of functional integration and resource-efficient extreme lightweight design, and demonstrates optimal use of airflow phenomena. It will provide important design insights for the further optimisation of future generations of cylinders and valves.
The onboard electronics ensure precise wing control. In addition, the torsion control parameters can be adjusted and thus optimised in real time during flight. The wing flapping and twisting sequence is controlled to within only a few milliseconds and results in optimum airflow around the wings. The SmartBird flight model has no rotating parts on its exterior and therefore cannot cause injury. It is further pursuing an approach that already played an important role in the development of the Bionic Handling Assistant: human-machine interaction. This feature of both the Bionic Handling Assistant and SmartBird poses no risk to the human operator. SmartBird thus joins the list of Festo’s future-oriented technologies that are expected to find practical application. Possible uses range from stroke wing generators in the energy sector up to actuators for process automation.
You can find more information about SmartBird, including a video preview of it in flight, at: www.festo.co.uk/bionic