Category Archives: arduino

Trashbot upper body and neck servos revived

I recently split my Trashbot in half to finally get hold on the walking patterns of the lower part, as I changed the controller from Arduino Nano to Raspberry Pi. Here’s the upper part:

Trashbot upper body incl neck & head

Trashbot upper body incl neck & head

With the recent progress of running Oculus Rift from a Pi 3 and the experiments of streaming video from the stereo cam Blackbird 2, I thought it was a great idea to attach the camera to the upper part of Trashbot and send the Oculus head orientation to the neck controlling Arduino Mini Pro.

First step is to get the Arduino run with the PC again. But oh, that shitty servo:

So, before diving deeper into head synchronous robotic telepresence, I’ll need to fix that bugger…

Arduino Tamagotchi, first power up!

That was more intense and exciting than I anticipated! I thought building my first “homebrew Arduino”  from an atmega 328p and controlling an OLED via I2C shouldn’t be too complicated.

In fact, it isn’t, but there are a couple of things you have to think of, especially when you do it in this contrained space.

20161204_173740sAnd actually, you can see the wiring mistake I did up there, I connected the RST of the chip and the DTR of the FTDI port wrong. But chip, FTDI and capacitor survived it…

I also did the buttons wrong as the buttons were rotated and always ON / HIGH. So, I changed the layout from this:20161204_183737s

To this:20161211_212541So now the power is on the upper part of the buttons, instead of the right (for the left buttons).

Yeah, so finally, here’s the first power up! The date / time is wrong because the third perf board with the RTC and the speaker are not connected yet, so the clock starts when the atmega is powering up:

 

 

Arduino Tamagotchi from the left

Arduino Tamagotchi – first board fitting (Pt 2a of 3)

The design principle of keeping everything to a minimum is also paramount in the Tamagotchi project. In this case, I wanted to use the Arduino chip itself and layout a board around it by myself and luckily, I also found out that my slaughtered external phone battery delivered 5.1 Volts which is in the operating range of the Arudino.

Tamagotchi PCBs

Tamagotchi PCBs

Top left, you see the front board with the display and the intended buttons (only one placed), top middle the board for the Arduino and it socket plus an USB port that will be used for the LiPo charger board (the one that is close to the battery) and on the right it’s the back plate containing the speaker and the RTC board. Continue reading

breadboard tamagotchi

palmsize Tamagotchi

Recently, I’ve come across a really nice Tamagotchi project on Instructables.

Tamagotchies are virtual pets in little devices (later on also apps, etc) that the user has to feed, clean up after and play with. They are a nice addition in my thinking on social robotics. Also while still collecting knowledge for the 68k computer, I learned that I want to start with a stripped down Arduino, not a Nano I usually work with. So this is an ideal little weekend project to learn a few things. Continue reading

first “unit test” in programming an arduino mini pro

so, after i’ve connected the head and its servos to trashbot 6, it’s now time to work on the actual control of the neck servos. unfortunately, the servo-board connected to the raspberry is not sufficient to control the neck servos since the body is already using 15 servos and the controller only has space for 16.

so i thought to use an arduino mini pro for this since it has 6 PWM outputs that can control six servos (people have noted that the output pin doesn’t necessarily have to be capable of PWM to control a servo). Continue reading

trashbot 6, quick video walk through

most of this work has been done over christmas, but only now i found the time to at least do a quick tour around the bot. here are some highlights:

  • arduino nano changed to raspberry pi 2 & wifi
  • moved controller from back to hips
  • added 16 channel i2c servo controller
  • new foot construction adding an additional degree of freedom (DoF)
  • reconstructed legs that are lighter and now take up new batteries
  • power distribution board including i2c current / voltage measurement
  • accelerometer and gyro sensor (i2c) moved to “belly” instead of neck
  • added arms with shoulders (two DoF)
  • changed spine, reduced complexity
  • removed head for now (being redesigned)

Trashbot 5, new hips, first movements

Last week I added three degrees more to Trashbot, two hip servos for forward movement (“kicking”) and one to the bone.

This week I found some time to do the first single servo movements and tests to check out the new geometry of the bot since the broader hips will affect the Center of Gravity etc. Here’s the first attempt to do what the normal gait would do: shift the body to one foot:

So, definetly software teaching me how to improve hardware… Next draft iteration: Continue reading

Working on more Degrees of Freedom in the legs of Trashbot

I’ve been working on Trashbot for quite a while now, but the basic gait mechanism is still the same as in version one. The hips’ movements and the distance between the legs define the possible step length. This is annoying since the robot is rather tall and you’d expect that he’ll walk a bit faster than he actually does. However, moving faster induces stronger vibrations in the skeleton and makes him fall much easier.

trashbot 4 in full length

Also, the upper part of the body will tilt “stronger” when Continue reading

trashbot 4 fully assembled

trashbot 4 and more

this time it took really long to make more progress on trashbot but i had the feeling that there were many little improvements that made the bot better and somehow it felt like none of them were big enough to be worth a post.

now in the end i learn that quite a lot happened during the last 8 or so weeks and over easter i invested some time also into the cleanup of the software.

first of all, i added shins to the legs so that he wouldn’t swing too much when shifting his weight from one foot to the other. i used some screw / hooks that you use to hang wired lamps and have a tension on the wires:

IMAG0948r

next i couldn’t resist to Continue reading

using a laser to investigate trashbot 3’s walking pattern & balancing effects

recently, i had the idea to attach a laser pointer to trashbot’s neck and investigate the amplitudes of the laser on the ceiling. this time, the blog entry is shorter but the “how-to” is in the video:

from the results you can see much better the difference between active balancing:

laser active balance

vs no balancing (the spine is stiff, the upper body moves with the hip, thus larger amplitudes):

active spine off laser

with this technique, i hope to be able to document further improvements on the movement, especially when i connect the gait pattern with the balancing mechanisms as scientific robots do.

i recently contrasted trashbot 3’s walk with the spine balancing or bein static and was not happy with the result of the video. one can have the impression that active vs non-active balancing is somewhat similar but in fact the real robot “feels” different as we’ve seen in the video above.

next, i’ll attach a little camera (gopro clone) to the trashbot’s chest to view the gait from “first person” perspective…