Matarić, M. J. (2007) The Robotics Primer, Chapter 3: Food for thought:

Q1: What do you think is more difficult, manipulation or mobility? Think about how those abilties develop in babies, children and then adults.

A1: This is a good question. Locomotion is difficult for a number of reasons. If a robot was just navigating around on a 10'x10' 2 dimensional square then locomotion is relatively easy. However we have all different types of terrain and each one has it's own challenges; some examples: Ice is cold, hard and slippery so it provides very little traction. Loose sand also provides little traction but it can also be hot and, in a way, soft. On land there are typically plants such as trees, rocks and tall grass which create obstacles and are visual impairments. Water is a completely different beast altogether. A robot would have to swiim like a fish (in a 3D environment) or drive along the bottom of the water with numerous other obstacles like rocks, plants, aquatic creatures and cliffs. And a last example is stairs which are typically found inside/outside of buildings. It is very hard for a robot with wheels to climb stairs.  

Manipulation is also a very challenging action since this requires fine motor skills, measurement and precise 3D coordination. Some objects are very soft or brittle and would possibly be destroyed by a hard mechanism that uses lots of pressure to pick it up. For example if an egg was picked up by a excavator type grabber the it would likely crush the egg (although I did see a video of someone doing this exact same thing to place an egg on a bottle). Some objects are very heavy and require lots of torque or power to move. Some other things require special handling procedures such as radioactive materials or molten metal at a smelting facility. At the same time the robot is manipulating any given object, it also is wise if it is sensing it's environment in other ways in order to complete it's task. This could mean making sure people in the surrounding area are safe, turning on a cooling system if the ambient temperature is too hot, or adjusting actions based on external forces such as wind or rain.

Using human development as a way to figure out which is more difficult; locomotion or manipulation. It would seem like locomotion was the more difficult action. Babies can manipulate toys much sooner then they can move around freely, and once they gain the ability of moving freely, then there is a very big risk that they could be harmed by falling off of furniture or stairs so someone has to be close by to watch them. That is the only reason I came to that onculsion though. Otherwise they both seem to be very difficult to master.

Q2: How large do you think your sensor space is?

A2: I think human sensor space is infinite, since the Robotics Primer book says that analog inputs and outputs are infinite. We can detect an infinite range of temperatures with our skin. We can detect an infinite amount of visible light (in the form of colors) in the electromagnetc spectrum. We can hear infinite frequencies between 20Hz to 20kHz. We have built in gyroscopes in our ears to detect orientation. We can detect infinite.... tastes and smells? I didn't know how else to write that. Everyone's sensor space is different though. I sometimes can't smell at all. Some people are deaf and cannot hear and other are blind. Typically other senses become stronger though which is interesting. 

Q3: Can you think of things or information in your life that is observable, partially observable, or hidden?

A3: Observable information is when the perceiver has visibility to all information that is available to them. I guess an example of this would be a light, where you can clearly see what state it is in on or off. Another would be a digital thermostat where it lists exactly what temperature it is in your house when you look at it. Partially observable information means that you have only a fraction of the information available to you. There are probable many examples of this but I can only think of a few. One is if someone was telling you a true story, but they left out some important information. Another one is if the weather forecast specified a % chance of precipitation, but they didn't tell you how much precipitation (in mm) was going to fall (This one bugs me a lot!). Hidden state means that you don't have any information at all. This one is not very clear because there's usually a way to at least get some information about anything. An exampe of this I think would be a battery by itself. It would be amost impossible to know what state the battery was in by itself (unless you licked it and felt a charge). You would need a multimeter or some equiment to plug it into to determine the charge.