Linear Motion

The other day Brett and Joel got a foot on the robot to move in a straight line! This required coordination of multiple joints and path planning.

They used the Arduino Teensy board that Joel developed as the leg controller, talking to a computer running some python code that Brett wrote to do path planning and kinematics.

Check out the videos!


State of the robot

Here’s where we’re at.


Physical robot is mostly done

Stompy is built!  There are six legs, a chassis, a roll cage, and an engine.  The engine runs and powers the hydraulics.  All of the hydraulics are hooked up and working properly.

There is still some work left to be done on the electronics.  All six legs have a sealed Leg Controller enclosure with a Beaglebone Black inside.  The Beaglebones have custom perf board capes.  Each cape carries a Dual MC33926 Motor Controller, which can drive four PWM channels to control two pistons.  The current plan is to drive the Knee and Thigh joints with those two channels, and add three more boxes located on the chassis to drive the Thigh joints.

All of the Leg Controller boxes are wired up to the network switch.  We can plug a laptop into the switch and talk to all the Beaglebones in the legs.

The Beaglebones don’t have software to do closed loop control yet, but we can SSH in and directly set the PWM outputs to move the Knee and Thigh joints.



Most of our activity right now is focused on software.  We recently decided to run our code in ROS and have been spending a lot of time getting the ROS ecosystem up and running.

We have a SDF file that Brett Graham put together a little while back.  He even linked in the Solidworks files for the robot, so we’ll be able to simulate a realistic model of Stompy in Gazebo.


Current Tasks

Seth Woodworth and Robin Garner have been working on using Vagrant and Ansible to automate building virtual environments.  The goal is to be able to repeatably spin up a virtual machine with the ROS environment set up that we can use for development.  Hopefully we will be able to use the same Ansible setup to deploy directly to the Beaglebones on the robot.

Spark is working on getting a launcher script to run nodes on different machines across a network.

Chris Stokes has been investigating the SeeedStudio Motor Bridge Cape as a new option for a motor controller cape.  If we switched over to it, it would replace the custom perf board capes as well as the MC33926 motor controllers.  This option would allow us to control all three leg joints from the Leg Controller BeagleBone.  There are pros and cons to running all three leg joints from the Leg Controller, but overall it’s probably preferable to do it if we can.


Here are some more photos, and a video showing the constructed robot.

Enclosure for a Leg Controller
Enclosure for a Leg Controller
Stompy's hydraulics powerplant
Stompy’s hydraulics powerplant