Robots That Jump

Robot Bodies Needed Before Robot Minds

Robots That Jump – Historical Apr 4-8, 2004

Thursday, April 08, 2004

Sensors, sensors
I was thinking about the fate of CMU’s Sandstorm in the 2004 DARPA Grand Challenge. After hanging up on an embankment, the robot car continued to spin its wheels, causing the rubber to burn off in a cloud of smoke and flame.

Hmmmm…for all the speed and power of that system (and it looks by most competent while driving) it couldn’t tell it was stuck. To me, this indicates that the robot is paying too much attention to the environment without checking its own internal state. The thing at issue here is sensors. Any biologist will tell you that simple animals don’t have elaborated brains – but they have a huge load of sensors. A single bacterial cell has thousands of protein-based sensors – measuring temperature, pressure, salinity, light, and chemical composition. This complex sensor array is coupled to a few simple outputs, like whether to divide, swim, tumble in space. This patternis repeated with more complex organisms – very rich sensor nets coupled with simple processes at the decision-making level and motor output level.

How would this work in a robo-car like Sandstorm? Well, I have a smoke detector above my computer which is relatively cheap and works fine. If Sandstorm had a few of these in its wheelwells it would have sensed the problems with the spinning tire and shut off the engine.

I suspect that a lot of the “stupid” behavior of mobile robots is simply due to their extremely limited sensor set. An insect has tens of thousands of sensors on its body recording a variety of stimuli (light, chemical, temperature, pressure). The very advanced QRIO robot that Sony produces probably has about 100. As the number of sensors increases we’ll see a version of “Moore’s Law” for robots – double the sensors, double the performance and apparent “intelligence.”

One could argue that this can be done in software. For example, if you program a routine that detects tires spinning without forward motion of a robot car you have de facto “sensed” a tire spinning against the ground. Fair enough. But this approach means that one has to figure out a huge number of environmental states in advance and figure out how to measure them in software using a limited sensor set.

Frankly, a smoke detector in the wheel wells seems easier.

One thing I’ve noticed about robotics work is that everyone seems to work with a small number of sensors. IR, ultrasound, laser rangefinder – we see them again and again. Nothing wrong with that. But this means that anything not easily processed by these systems in the environment has to be recognized by a software program.

The fact is, there are a huge number of sensors out there. Many are special-purpose devices designed for industrial robots and are very specific. There are sensors for heat, fire, rotary motion, proximity of metal (too close to another robo-car) windspeed using ultrasonics, temperature, humidity, strain, hydraulic pressure, ionization, low-level acoustic (detect change in standard sounds like an engine), magnetic, compass, a variety of gases like CO, O2, CO2, and biogenic gases, leak detectors, movement, radiation, micro cameras, sudden motion (airbags), moisture in oil. and more. To see examples of this go to the Direct Industry website and search for “sensors.” You’ll get a huge amount of information. A lot of these sensors are relatively small – too big for a hobby robot, but fine for a pickup truck.

I wouldn’t say that the extreme focus on robot vision for the fast 40 years is misplaced, but it is inadequate. During the 2004 Grand Challenge, Digital Auto Drive performed beautifully in termse of vision – but got stuck (lightly) on a rock. The robot sat there revving its engine but not enough to free itself. If it could “feel” the rock it could have determined its state and possibly got free. A human driver got the DAD car free in a couple of seconds becaus they could “feel” the rock themselves through the vibrations of the car transmitted to their body. They didn’t have to see the rock. Vision is not always necessary to solve problems. The right kind of sensor can pick up very specific information that can be handled as a low-level reflex rather than requiring high-level computing.

My image of an “alternative” robo car would be to cram the system with as many unique sensors as possible. Put in a few obvious low-level reflexes (e.g. tire smoke in the wheelwell tries to shut off the engine). Use a subsumption-style architecture to allow override in special cases – but do that later. Don’t worry about the complexity explosion of monitoring large number of sensors – tie them up with simple reflex circuits. The “brains” of the robo-car would normally only get the message that nothing was wrong.

I’m guessing a sensor-rich carbot would have a better chance of completing the course than a comparable system with super-vision processing and few sensors.

Finally, trying out some of these strange, alternative sensors that mobile robotics groups don’t use today might lead to some insights. Just possibly, there’ too much focus on a few well-known sensors at the expense of the others. So dig through a list of every sensor out there and try to think of creative ways to use them. If your’re a hobbyist, do the same – dump the standard IR or sonar sensors for something really different. By doing so you’ll be bringing us closer to robots that jump.

Sunday, April 04, 2004

Robot Cars are Important – They Can Jump!
I just had an article published on Robotics Trends (http://www.roboticstrends.com entitled “Why Robot Cars are Important.” The exact link to the article may be found here. So why tout wheeled vehicles on a blog devoted to robots that jump? Well, if you think about a car as a robot body you’ll see it is far better than most of the bodies constructed in a one-off fashion in academic research:

  • Robot cars are sensitive – modern cars are loaded with sensors, mostly of the MEMS variety. In addition, a sensor network connects the sensors to low-level regulatory brains. So a robot brain can immediately take advantage of the car’s built-in sensors.
  • Robot cars are powerful – A huge problem with mobile robots is power. The Asimo can only run about a half an hour between recharges, and the new Toyota trumpet-playing robots have similar limitations. Hobby robots run with ancient microprocessors dating from the 1980s in part because these sloooow chips consume very little power, allowing the hobby robot to run with batteries. In contrast, a robot car has power to burn. The engine can supply lots of electrical power, or a second generator may be placed in the car. A fully-fueled robot car can run for 10 hours or more while moving down the highway, at the same time powering several multi-gigihertz computers. If a network of low-power PC boards like those from VIA are used, you can put a supercomputer in an SUV.
  • Robot cars can use standard computers – The power problems on mobile robots have led to custom hardware solutions. In contrast, a robot car can use a computer you get from Best Buy. This allows hobbyists to experiement with high-powered computing for their robot at a relatively low cost.
  • Robot cars have standardized bodies – Unlike a “one off” robot body, cars are mass produced. If you design a robotic system for one car, you can use it in thousands of others like it.
  • Car races are a proving ground for social robots – In a race, both competition and cooperations are required. A car passing another must cooperate or they’ll crash, but must compete to win. This is a simplified version of real-world social systems, ideal for early robots to master.
  • Cars don’t have the “terminator” stink – Humanoid robots invoke a Hollywood-conditioned fear response, at least in the US. In contrast, we don’t have strong feelings about the good or evil of robo cars. There are some negative images (“Christine”) but some fun positive ones (Knight Rider’s KIT, Love Bug). And who wouldn’t want their car to have a personality.
  • People love cars – The fact that millions of people go to see car races means that there’s a market for building expensive car robots outside the military – NASCAR. We already have some early robot races going. In a decade, the cars will have electronic “personalities” like pro wrestlers. Who wouldn’t love it if a “monster truck” really wanted to crush small cars with its huge wheels? The car is a celebrity today like the driver. Tomorrow, the car alone with be enough.
  • Robot cars can jump – Unlike other wheeled robots, cars are tough and reliable. They can drive a high speed, spin out, and – of course – jump through the air. With the use of pneumatics (powered by the car’s own engine” one can put in airshocks, even Shadow air muscles and give the robot car a musculature. Unlike weak metallic muscles, pneumatic muscles are strong. Imagine a robot car jumping up and down on its air shocks for the fun of it, or to “intimidate” another robot car?

    Calling all robot – people – get outside and start hotwiring your car into a robot!

    Also check out the International Robot Racing Federation at http://www.irrf.org.

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