When talking about legged motion in robotics, we typically cite the number of legs and make assumptions based off that figure. For example, if I say something is bipedal, you typically thing of a humanoid walking system with an upright stance and gait. If I say quadrupedal, you would likely assume something like a dog, and if I say hexapod, you're likely already cringing with thoughts of insects and arachnids.
This robot, called iStruct, hopes to escew these assumptions in an attempt to be more varried in its capabilities. Looking toward nature, we can see some specific examples of creatures that are capable of switching between quadrupedal and bipedal walking. Non-human primates can adjust their locomotion systems to traverse varied terrain. They can cover distance quite quickly using all four legs, and we've seen them switch to bipedal walking when they have their hands full. Based off of a primate's anatomy, this robot looks and walks like a baboon.
Several areas of the bot carry some interesting advances. The complexities involved in transitioning between the two modes of locomotion can be focused on two areas: the spine and the ankle.
A flexible spine allows the bot to shift from the curved spine in quadrapedal mode, necessary to retain forward-looking head placement, to the straighter spine of the bipedal mode. The midsection of the robot mimics the muscles and tendons necessary to hold the body upright in the bipedal mode.
The hind foot
A typical quadruped has a single-point-of-contact-style foot. Apart from the added stability of three feet being in contact with the ground at any given moment, any more foot parts are unnecessary. In bipedal motion, however, a foot with multiple actuated parts can help with grip and balance.
Just like the Wildcat from Boston Dynamics, this bot is both terrifying and not necessarily useful in its own right. It is intended to be a development-and-test platform. You may not ever see baboon bots roving the streets, but you may see a nice prosthetic ankle that owes its design to this bot.