Design Principles

Spiri robots are designed to be autonomous, versatile, powerful and maintainable. Spiri robots are also designed to be familiar and inspiring. In this essay we will discuss some of the choices we made to put these ideas into practice.


The requirement for Spiris to be able to act on their own, either as individuals or in splendors, meant we needed them to have the best possible sensors, and the best possible “brain” to process the information from their sensors. We picked a main computer with lots of parallel processing power, as this is the best way to handle images and make inferences. The size and heat generation of the main computer set a lower limit on the size of the Spiri Mu.


We saw Spiri as a genus of robots capable of taking on many different missions, and so within each “species” of Spiri robot, we wanted to make sure it was easy to add special equipment, change behavioral characteristics, and so on. That is why we chose to have multiple open input/output ports available, and to provide local- and server-based support for switching Spiri personalities. For example, the Spiri Mu can be configured for upside down flight with a change of propellers and firmware. It can switch between indoor and outdoor modes. It can be an individual or a member of a formation. In formation, it can coordinate either client-server or peer-to-peer. The choice to use 3D printing for the mechanical parts was also partly in support of versatility — parts can be customized for adding extra gear.


We took care to provide Spiri with four kinds of power: computing power, sensing power, propulsion power, and teamwork power. The first three set requirements and constraints on the physical design of the robot. This is why Spiri is so compact — extra material is simply a drain on the thrust-to-weight ratio. This is also why we favored computational efficiency (parallel processing with lots of optimization) over processor size. The Spiri Mu is unequalled in terms of practical operational “thinking” per non-battery gram of robot and it fits into carry-on luggage. As for teamwork, this comes into our collaborative software, but is also supported by the compactness and versatility of a Spiri. We designed around the possibility that within a Spiri splendor there could be lots of specialization, robots with different jobs and equipment working together.


Spiri is a premium product and it should last a long time. At the same time, rapid improvements in battery, sensing, computational, and materials technology will make many of the components in a Spiri obsolete over time. Our approach to this issue is to modularize the build — any given component is made to be interchangeable with its replacement without affecting the rest of the robot (except to improve the function of the given component, of course). When you open a Spiri you will see how the functional areas are isolated for this purpose.


We intend for any Spiri to be able to interact closely with the rest of us, in spaces designed for humans to live and work. For this reason, we wanted Spiri to behave and sense in intuitive ways, for example having cameras like eyes pointed forward, to be left-right but not forward-back symmetrical like an animal, to be able to read signs and gestures. This makes its movements more predictable for us. We gave the Spiri Mu a more aqueous than birdlike or insect form, to match with the sense of it floating in air rather than gliding or flapping in it. We also worked to make it safe around us, with the option for propeller guards, the ability to deal with bumping into things, and a size that makes collision with a Spiri, while painful and dangerous for the eyes, otherwise not a danger to life or limb — the difference between stitches and lost fingers.


Our hope in designing Spiri is that it will inspire both hardware and software innovation. Everything we’ve discussed above is a part of that; our design is intended to provide a platform that helps you achieve autonomous goals, that is given to lots of variation, that has the computing and physical power you need, that will last a long time and permit lots of repair and upgrade, that behaves predictably and safely, and that makes you feel good developing on it. Like you, we are learning as we go, and look forward to seeing what you make of Spiri.