Recently Schaft, a robotics company owned by Alphabet, unveiled a new bipedal robot. The robot is basically, two legs that can waddle around.
Schaft has a good history in advanced robots since they won the DARPA robotics challenge and certainly have a great deal of talent in their team. But what are the actual challenges of building a walking robot?
When you stand there is really not too much going on that a robot can't do. Liquid filled sensors in your ears determine how you are angled, similarly to how an accelerometer in a robot does. Once that angle is determined, within your brain then a command is sent to muscles in your legs to adjust and move your center of gravity back over your feet, which again is what robots do. But there are a few major differences. The first is that our computer is vastly superior to any inside of a robot, and we have dozens more muscles than many robots today, so we can make small, imperceptible changes to our entire body rather than just tilting a bit, as a robot is required to do. Though it should be noted that many robots don't do that. When they stand they attempt to get into a position where they are basically a solid structure. They are basically "propped" in a standing position. While our brain continues to think about standing while we stand a robot basically shuts down once it feels that it is stable.
Now, with walking, everything becomes very complex from a design and control standpoint. Humans walk by using our perfectly engineered legs. Throughout the motion of taking a step, we use gravity to swing our legs forward and more or less use our muscles just to make a controlled fall into a new step. The only time our muscles are really activated are when we push off from a step. But all of out motions are very fluid and smooth. This gives us a phenomenally efficient means of locomotion.
When you look at a robot walking, most of the time you will see them slightly crouched. Their knees are continually bent and their torso is upright. What the robot is doing is making sure that it is always in a stable positions. They try to be a rigid structure so that if a leg ever goes on the fritz it will appear that the robot is just stopped mid-step. Robots like Honda's Asimo and all hobby humanoids use this methodology. Instead of using a human-like controlled fall, they first try to remain standing in any position.
Though robots are beginning to move away from the "moving structure" design. Boston Dynamics has really lead the charge in this front. Their robots look very human when in motion. They are relatively fluid and actually use hydraulic actuators instead of motors to better replicate the human musculature. The robots revealed by Schaft also seems to be very fluid, though it uses electric servo motors. The holy grail of walking robots is fluidity.
When a robot is able to move without looking like a machine, that is breakthrough. Fluid motion in a machine denotes efficiency. Walking robots are notoriously inefficient. While they move like a rigid structure most times they still have their motors activated when standing in order to hold the position. And when they walk in a crouch you can understand how much effort it takes. Go ahead and crouch a bit and then walk a ways. You will feel the burn.
So why don't we just simplify the walking to make it more fluid. The reason for that is in the what are called control algorithms. These are mathematical formulas that describe the motion of the robot. These algorithms allow the robot to predict how it is moving with accuracy. As it turns out, the crouched, "moving structure" method is easier to model than the chaotic "controlled falling" of a human. Though simulations and computing are getting to a point where human walking is becoming possible to model.
Let me put this in perspective as to the challenge. When Asimo was being created, engineers were likely designing much of his algorithms on paper. They would lay out the overall design and control variables, like gravity, and acceleration, and then perhaps feed them into a computer to some analysis. For a robot that is a "moving structure," that is possible because dynamics are not highly involved. But when you move into the design of a human walking robot you must consider hundreds if not thousands of changing circumstances. You must detect how the swing of the leg induces a rotation on the body. You must perceive ground conditions. You must remain balanced and in control even while falling forward and ensure that the leg is going to contact where you want it.
Let me make another comparison. In four legged animals 3 legs are always on the ground. A horse can stand on three legs and then extend out a fourth to take a step. The stepping leg is independent of the rest of the body. the body stands there rigidly and the leg moves ahead. This is what robots like Asimo try to achieve. Now consider a horse running. In this situation maybe one leg is on the ground at any given time and the entire body is moving forward and adjusting to remain balanced on changing terrain. In this situation on leg must move with all the rest of the body in a glorious symphony otherwise the whole system comes crashing down.
A bipedal robot that walks like a human in a running horse. Everything within the body of the machine must interact and move together so that it does not crash and burn. Imagine trying to develop an equation that describes every component of those motions, down to how quickly a hand must swing forward when a foot slips a quarter of an inch from where it was placed.
Those are the challenges of designing and building an advanced bipedal robot. Boston Dynamics has done an incredible job achieving these with their robots. But the trouble is that they have hit a common problem in the robotics industry in getting customers, their robots are very expensive. Schaft appears to have created something that seems to move fluidly, but it also appears to be less complex. The greater simplicity may make it much less expensive than a Boston Dynamics robot. If it is affordable enough Schaft may bring walking robots into use in industrial areas relatively soon, where wheels robots have been dominant if used at all.
I would imagine that walking robots would find use in areas like construction where transport over uneven areas is necessary and is tasks that humans do not enjoy. As far as walking robots in your house. Probably not for awhile.