PYRO
I have replicated some four-legged robot projects and even with good documentation it is often not possible to follow the installation. There are extreme dependencies on the OS and many software packages, especially when using ROS, which even with a successful build can make long-term operation questionable. Therefore my attempt to build a robot based on a Pi 4, python and other elementary packages.
I was able to rebuild these two projects very well and I learned a lot.
https://github.com/PetoiCamp/OpenCat
https://github.com/mike4192/spotMicro
Furthermore, I decided to work with hobby mini servos like MG92B for the small prototype. They are affordable, sufficient as proof of concept, and if everything goes well you can still realize a big dog. The big version uses PDI-HV5523MG 23KG servos.
setup raspian 2022-04-04-raspios-bullseye-armhf.img.xz
sudo apt-get update; sudo apt-get upgrade
sudo apt install pi-bluetooth
sudo bluetoothctl
pairable on
scan on
scan off
pair A4:AE:11:DE:4E:BB
trust A4:AE:11:DE:4E:BB
wget http://repo.continuum.io/miniconda/Miniconda3-latest-Linux-armv7l.sh
sudo /bin/bash Miniconda3-latest-Linux-armv7l.sh
source ~/.bashrc
conda create -n env106 python==3.10.6
conda acivate enc3106
/home/pi/.conda/envs/env3106/bin/pip install python3-pip
pip install adafruit-blinka
pip install python3-numpy
pip install adafruit-pca9685
pip install adafruit-circuitpython-servokit
pip install adafruit-circuitpython-mpu6050
pip install pyPS4Controller
pip install urdfpy
pip install pyPS4Controller
pip install matplotlib
sudo apt install i2c-tools
sudo raspi-config -> enable interfacing, i2c
sudo chown :i2c /dev/i2c-1
sudo chmod g+rw /dev/i2c-1
install configparser
sudo apt install git
Servos:
PDI-HV5523MG 23KG High Precision Metal Gear Digital HV
Operating Speed (8.4V): 0.16 sec/60°
Maximum pulse width: 500-2500us
To move the motors to a defined starting position at the beginning (init), I control the motors one after the other, because I am still working with a laboratory power supply, which I cannot load highly. Later, the power supply will be taken over by a Lipo, which can deliver the necessary high currents, then the motors will be controlled simultaneously.
Version_Step_1.py:
Basic movement, static, no inverse kinematic yet
Implemented rest, sit, calibate and stand/balance for testing the servo control and motion.
Done.
Version_Step_2.py:
Inverse Kinematics
Moves using the great package from Mike (https://github.com/mike4192/spotMicro):
git clone git@github.com:sffranke/spot_micro_kinematics_python.git
Done.
Version_Step_3.py:
Add PS4 Controller for posing.
pyro.py c -> calibration pose
pyro.py r -> rest or init pose
pyro.py b -> stand pose
pyro.py i -> sequence of inverse kinematiks poses for testing
pyro.py without argument runs the PS4 Controller:
Press X-Button: rest and exit programm
Press Square-Button: rest or stand pose
Press Circle-Button: sit or stand pose
press Options-Button: calibration pose (LL)
Done.
Version_Step_4.py:
Added conig file confg.ini for properties and servo parameters.
Done.
Version_Step_5.py:
Add MPU6050* for balancing
PS4 Buttonon_share sitches MPU Messurement and correction on and off for balancing in pitch axis and roll-axis.
Done. Fine tuning later. Needs the Lipo now for balancing.
Walking
In progress, coming not so soon :-)