A new generation of ambulatory machines is striding to market
It is easy to conclude, as many do, that these new walking robots simply mimic nature. But that is not quite the case. A quadruped, being a stable platform, is a good starting point from which to design a walking robot. After co-ordinating the four limbs, getting a good balance and fitting a system of vision that lets the robot work out where to put its feet, Spot’s designers ended up with a dog-oid. Michael Perry, head of business development for Boston Dynamics, says that is not surprising because nature has been developing efficient designs for a long time.
Another example of art evolving to imitate nature occurred during the design of Digit. This inherited its ostrich looks from Cassie, a two-legged torso which Agility sold to a number of research groups. Cassie’s developers had to find a way to stop some of the robot’s actuator motors from working against each other. Their solution turned out to look like a pair of bird’s legs.
Cassie subsequently acquired arms and evolved into Digit as the result of the engineers’ attempts to solve another problem. When it swung a leg forward Cassie’s body twisted a little, which sometimes caused the robot to fall over if it was walking quickly. In nature, some animals use tails to improve their balance when manoeuvring at speed. Borrowing this idea, Agility’s researchers attached a pair of tail-like appendages, one on each side of the robot’s torso, to improve its mobility. That worked. Then they turned the appendages into a pair of arms. These can catch the robot should it fall, and help it get up again.
The arms can perform other useful tasks, too, such as moving boxes in a warehouse. Digit can carry up to 20kg. Distributing and delivering goods is likely to be an important application for walking robots, reckons Dr Hurst, especially now that e-commerce has boomed as a result of restrictions imposed in the wake of covid-19. Some automated distribution centres are set up for conventional fixed and wheeled robotic systems, but these have usually been built this way from scratch. Most warehouses are designed around people. Robots with legs, which move in a similar way to human workers, would fit right in.
With further development, walking robots will undertake more complex tasks, such as home deliveries. Ford is working on this with a Digit robot that rides in the back of a van. Though robots with wheels already make some deliveries, reaching many homes is tricky, and may involve climbing steps or stairs. “Legs are how you would want to get up to most front doors to deliver a package,” observes Dr Hurst.
Exactly how this might be done remains to be seen. Unless they are on a preprogrammed mission, most mobile robots require an operator to provide basic instructions to, say, proceed to a certain point. The robot then walks there by itself, avoiding obstacles and climbing or descending steps and stairs along the way. This means a walking robot making door-to-door deliveries might need some kind of digital map of the neighbourhood, to know in advance the paths it can traverse and the flower beds it should avoid. That might involve a big data-acquisition effort, much like those used to build digital maps for driverless cars. Similarly, in a factory or a warehouse, a walking robot would need to be shown the ropes by a human being before it was let loose to work on its own.
A fully autonomous robot that could walk into an unknown environment and decide for itself what it needed to do remains a long way off. One of the hardest tasks for such a device would be caring autonomously for someone at home. The robot would have to be able to make numerous complex decisions, such as administering the correct medicine, deciding whether or not to let strangers into the house or knowing when to take the dog for a walk. Yet many roboticists think they will get there, or at least close to it, one day.
In the meantime, the new generation of robots now being developed will keep building up the machines’ capabilities. At Boston Dynamics Mr Perry reckons that, besides surveying, Spot will find many roles in inspection and maintenance. Such robots can, for instance, enter hazardous environments like electrical substations without them having to be taken off the grid, as is necessary whenever a human engineer goes inside.
Instead of just looking for problems, Spot’s next trick will be to take action to resolve them, such as throwing a switch or turning a valve. It will do this with a single manipulator arm which makes it look less like a dog and more like a long-necked Brachiosaurus. A prototype of this configuration is already running around the company’s offices, opening and shutting doors.
This version of Spot should go on sale next year. As for Atlas, Boston Dynamics’s humanoid, that is currently too expensive to spawn a commercial version. But the lessons being learnt from it will help provide the engineering needed for other robots to come, says Mr Perry.
Some of these walking robots of the future may not be deployed on this world. At Caltech, Dr Ames thinks robots with legs will have advantages in planetary exploration—negotiating difficult terrain and entering caves, for example. Meanwhile, back on Earth, he and some colleagues at other institutions are using the new knowledge of robotic locomotion to develop lightweight prosthetic devices for those unable to walk easily, and powered exoskeletons for those who cannot walk at all. In a world not made for wheels, this raises the tantalising prospect that walking robots will one day help rid the world of wheelchairs. ■