– BY LAURI POLDRE
Birds are the most efficient flying “machines” in the world. I had the opportunity to talk to Markus Fischer, Head of Corporate Design in Festo AG & Co. KG, German based engineering-driven company in pneumatic and electric actuators industry. Festo’s SmartBird is an innovative mechanical bird that they recently built to explore bird’s flight and challenges in the lightweight construction. See SmartBird in flight, check the video.
Lauri: Why Smartbird? What was the idea behind this project?
Markus Fischer: The objective of the project was to construct a bionic bird modelled on the herring gull. The fascination of building an artificial bird that could take off, fly and land by means of flapping wings alone provided the inspiration for our SmartBird’s engineers.
Lauri: Working on such a large scale projects takes abviously lot of time and effort. How many hours did you spend for this project?
Markus Fischer: Yes, you are right. We spend many hours on this projects. It´s difficult to say how many, because it took several months to get the SmartBird to fly.
Lauri: How many prototypes did you develop?
Markus Fischer: We’ve only got three prototypes. They are on the road all over the world.
Lauri: How did you decipher the flight of birds?
Markus Fischer: The experience gained with the Bionic Learning projects AirRay and AirPenguin was incorporated into the creation of SmartBird. Moving air in a specific manner is a core competence of Festo that has been a driving force for the company for more than fifty years.
The unusual feature of SmartBird is the active torsion of its wings without the use of additional lift devices. The objective 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 lift, and maximum agility for the flying craft.
Under scientific supervision, an intelligent cybernetic overall design was realised in discrete individual stages. Flapping-wing flight comprises two principal movements. First, the wings beat up and down, whereby a lever mechanism causes the degree of deflection to increase from the torso to the wing tip.
Second, the wing twists in such a way that its leading edge is directed upwards during the upward stroke, so that the wing adopts a positive angle of attack. If the rotation were solely due to the wing’s elasticity, passive torsion would result. If on the other hand the sequencing of the torsion and its magnitude are controlled by an actuator, the wing’s torsion is not passive, but active.
SmartBird’s wings each consist of a two-part arm wing spar with an axle bearing located on the torso, a trapezoidal joint as is used in enlarged form on industrial excavators, and a hand wing spar. The trapezoidal joint has an amplitude ratio of 1:3. The arm wing generates lift, and the hand wing beyond the trapezoidal joint provide propulsion. Both the spars of the inner and the outer wing are torsionally resistant. The active torsion is achieved by a servomotor at the end of the outer wing which twists the wing against the spar via the outmost rib of the wing.
Lauri: Did you achieve your goals with the SmartBird?
Markus Fischer: Yes we did, and a lot more. The reaction to our SmartBird since its release has been really amazing.
Lauri: Did you use any innovative materials?
Markus Fischer: For the SmartBird we used:
- a lightweight carbon fibre structure,
- for the lining an extruded polyurethane foam,
- lithium polymer accumulator,
- 2x digital servo units with 3.5 kg actuating force for control of head and tail sections
- 2x digital servo units for wing torsion with 45 degree travel in 0.03 s
- Microcontroller: MCU LM3S811, 32-bit microcontroller@50 MHz, 64 kByte flash, 8 kByte RAM
- Radio transmission: 868 MHz/2.4 GHz two-way radio transmission based on ZigBee Protocol
- Motor: Compact 135, brushless
- Sensors: Motor positioning 3x TLE4906 Hall sensors
- Accelerometer: LIS302DLH
- Power management: 2x LiPo accumulator cells with ACS715 voltage and current monitoring
- LED activation: TPIC 2810D
Lauri: What were the main challenges when designing and building this man-made bird?
Markus Fischer: One of the main challenges was to make the bird fly, start and land autonomously, only driven by a control mode. The other challenge was the active torsion of the wings.
Lauri: What software did you use for engineering tasks?
Markus Fischer: The wing’s position and torsion are monitored by two-way radio communication with ZigBee Protocol, by means of which operating data are conveyed such as battery charge, power consumption and input by the pilot. In addition, the torsion control parameters can be adjusted and thus optimised in real time during flight.
Together with the electronic control system, this intelligent monitoring enables the mechanism to adapt to new situations within a fraction of a second. This facilitates the simple, efficient and weight-optimised mechanical design of the bird model for optimised efficiency of the overall biomechatronic system in flight operation.
Lauri: What is the practical use of such a bird?
Markus Fischer: For now the SmartBird is on the road all over the world to inspire people to take an interest in science and technology and by this get them interested in our company and solutions.
Lauri: What is the future of this project? What are your plans?
There are no explicit plans for the SmartBird. We don’t want to produce a swarm of SmartBirds, if that’s what you think. But we’re trying to copy the knowledge on topics like energy efficiency and lightweight construction to other products from Festo and those of our customers. We can use the learnings and offer ore efficient products and solutions to our partners.
You can get more info about this project from the Festo SmartBird website.