Robotics

This simple circuit can detect the invisible fields of voltage which surround all electrified objects

CALEB CHUNG: Of course we could have used micro-servo motors to accomplish the motion of Pleo, but we aren’t able to use expensive motors. So we had to engineer it with a high-speed motor with high gearing and no backlash for control purposes and have it all fit within the muscle envelope of Pleo.

So what we did was go after a lot of ethology research. How do animals really handle the complexity of their environment? We built a virtual brain—a whole system that decides how Pleo will react in various situations.

CALEB CHUNG: Pleo will reset thresholds and adjust his idea of what he thinks is normal. Let’s say you get Pleo and you take him home to your shag carpet. When Pleo walks, the carpet will drag on his feet. So his force feedback sensors will realize that he is spending too much energy to walk around. Pleo will try different things to reduce the energy spent. Eventually, he will have the idea to step higher. Your Pleo compared to my Pleo will walk with a higher step.

Pleo Technical Specs: Ugobe LifeOS 32 bit Atmel ARM 7 microprocessor - The main processor for Pleo 16 bit sub processor - The processor dedicated to the camera system (4) 8 bit processors that provide the low-level motor control for the servos (35) Sensors including a camera custom designed to fit into Pleo’s very compact body. (4) foot-switches to detect footfalls and being picked up - assists with spatial orientation. (12) capacitive touch sensors (4) legs, (4) feet, back, shoulder, head, chin (2) microphones for directional sound detection (14) “Force” sensors, one per servo, to recognize abuse through force feedback joints. Orientation/tilt sensor IR transceiver for bidirectional data communication with other Pleos. IR interrupter for detection of objects in Pleo’s mouth (14) motors. Standard low voltage DC motors (150) gears and clutches Rechargeable NiMH battery pack USB port with mini USB connector SD/MMC memory card slot

Pleo不仅拥有内置的触摸、感光、听觉系统，还能够随着环境的改变随时“学习”，适应新环境。对于感官上的刺激，Pleo会立即做出真实的反映

Pleo同样善于表达，喜怒哀乐，皆形于色。当他感到疲劳时，它会昏昏欲睡渐渐入睡，甚至会做梦——这可是机器人过去想也不敢想的。更令人惊叹的是它们还能识别同类！但是你得当心了，因为感冒也会在它们之间传播！对了，差点忘了，它们甚至还会有见到强光就喷嚏连天的Achoo综合症。

Note that the resistor value of the pull-down resistor affects the voltage at pin 3 of the Furby's connector. We used a 1k ohm resistor to make it less sensitive to light (since we're now operating with it open to ambient light).

In the above diagram, a 20k ohm resistor is used as the pull-up resistor. You can, however, use any resistor as the pull-up resistor as long as the resistance is high enough to protect the circuit.

attach your Pager Motors to your Popper using two Fuse Clips, two Small Paper Clips, and no solder

note that the human body is a good absorber of stray RF fields, so this sensor should be a good people-detector

Many Logo-based and other robotics products produced by LEGO are distributed to schools in the USA by Pitsco.

This free-range turtle does not require connection to a computer. All the controls are on board.

The Cricket is a tiny computer, suitable for all kinds of robotics projects, that you can program using Logo.

All Cricket devices have a built-in bidirectional infrared communications channel, which is used for Cricket-to-desktop communication (when downloading programs to a Cricket, or viewing sensor data) and Cricket-to-Cricket communication.

Cricket Logo is based on an iterative, interactive model of project development. It includes a “command center” window; instructions typed into this window are instantaneously compiled, downloaded to a Cricket, and executed, giving the system the flavor of an interpreted software environment such as LISP, BASIC, or FORTH.

The MetaCricket software system is based on a virtual machine, written in PIC assembly language and running on the Cricket, and a compiler for the virtual machine running on a desktop development computer

Motorcycle lead acid batteries work great for larger low performance type robots. They are great for solar power robots too.

lead acid batteries have the serious problem of being very large and heavy, need to always be kept charged, and do not have the high discharge rates as the more modern batteries.

They have low power capacities, are heavy, have trouble supplying large amounts of current in short time periods, and get expensive to constantly replace

how to interpret sensor data into a mathematical form readable by computers

There are only 3 steps you need to follow: Gather Sensor Data (data logging) Graph Sensor Data Generate Line Equation

Some sensors (such as sonar and Sharp IR) do not work properly at very close range

pseudocode: read left_photoresistor read right_photoresistor if left_photoresistor detects more light than right_photoresistor then turn robot left if right_photoresistor detects more light than left_photoresistor then turn robot right if right_photoresistor detects about the same as left_photoresistor then robot goes straight loop

Photovore Algorithm, Improved This algorithm does the same as the original, but instead of case-based it works under a more advanced Fuzzy Logic control algorithm. Your robot will no longer just have the three modes of turn left, turn right, and go forward. Instead will have commands like 'turn left by 10 degrees' or 'turn right really fast', and with no additional lines of code! pseudocode: read left_photoresistor read right_photoresistor left_motor = (left_photoresistor - right_photoresistor) * arbitrary_constant right_motor = (right_photoresistor - left_photoresistor) * arbitrary_constant loop

stimulus-response

a plan of action

combine the best of both Reactive and Deliberative control

Droidmakr (Cliff Boerema) came up with an interesting idea for a light-tracking head with a form of peripheral vision. As often happens, the circuit turned into something different -- a photopopper:

All done with a single 74HC14 (the '240 being a motor driver).

I tried the same setup with the 74*240 (with an extra inverter per motor) and 7404, but the 74HC14 seems to work best.

I wanted to share an adaptation of the Schead v4, that I have been experimenting with. It is (for lack of a better term) a Master/Slave Schmitt Comparitor Head (M/S SC-H). With the addition of a 74 AC 240 or two (as motor drivers) and a pair of motors, you can put together an interesting little light seeking, wheeled robot with peripheral vision.

As long as the light reaching the photo-bridge of the Master SC-H is balanced, then the Slave SC-H acts as a regular, lone SC-H would. So, if one of the slave photo-diodes detects more light then the other, the inverter that controls the motor on that side changes states and is now the same as the inverter of the Master SC-H tied to the same motor. This turns that motor off and the robot will pivot around the stopped wheel toward the greater light source until the light on each sensors is balanced and the motor again begins to turn.

I am also using SCar to continue experimenting with Stacking separate Sensor/Behavior circuits onto a robot. I will post more as progress is made.

It is powered with two 3.3F Goldcaps. They can be charged in a few seconds. When they are charged, MAXIBUg gets "afraid" of light, and wanders of to go to play "in the dark". After a while, about 20 seconds (depending on the current used by the two motors ), the power has dropped, and it wants to "eat". It gets light attracted, and will turn and go to the light. When it gets there, it will recharge and still will be atrackted to the light until it reaches a trigger voltage , at which it gets "afraid"of the light again. This will go on all day until someone turns off the lightsource. While doing all this it also will backup when bumping into something.

Because of the "on-off" output of the first schmitt trigger, the inputs for the LDRs will switch. That's why it gets light atracted -light afraid. This also means that you cannot use IR diodes (like SHF205). You have to use LDRs !