Table of Contents
Bipedal Robot Locomotion: Getting Started
Motor Interface
The biped is controlled using Dynamixel AX-12 and/or AX-18 motors. We have created a Matlab interface for the Dynamixel motors. This interface enables controlling the motor actuation, as well as reading motor values and parameters. There is even an associated trajectory class that takes in trajectories and can replay them.
1. Go meet up with the biped contact and complete #1 (Hardware Setup) and #2 (Matlab Interface) of the Dynamixel Tutorial.
Submit a live demo or, alternatively, a (link to) video showing completion of Exercises 1 and 2 in Matlab Interface.
Robot Model
The first step here is to get to know the biped, as well as to model the biped that you will be using. Depicted below is a sketch of the biped model.
2. Measure the link lengths for your biped and submit values for $l_0$ to $l_4$. If there is no $l_0$ value yet, then use something sensible and state as much. Use this value for now. Later, it will get locked down.
3. Using the picture below as a guide, submit a stick-figure sketch of your biped robot using lines to depict links and with a frame rigidly attached at each joint. Each frame should have one of its axes aligned with a link. Additionally, submit the forward kinematics that describe the left foot frame relative to the torso frame ($g^T_{LF}$), as well as the right foot frame relative to the torso frame ($g^T_{RF}$). Placement of the torso, left foot and right foot frames are depicted below.
4. Download the Matlab Biped class skeleton code: Biped.zip. Fill out the following functions in the Biped class: 'set_geometry( … )', 'set_alpha( … )' and 'fwd_kinematics( … )' according to the descriptions in the in-line comments.
5. Flesh out the plotTF member function of the biped class. It should use the 3 functions completed for #4 and plot the robot relative to the torso frame. As long as the torso frame is not set to anything, then it should plot at the origin (meaning the torso frame is in the identity configuration). The predicted, forward kinematics left and right foot frames ($g^T_{LF}$ and $g^T_{RF}$, respectively) should each have one axis align with the feet for whatever joint angles are chosen for the manipulator. In essence, executing this function, together with plots of the reference frames should give a nicer version of the picture below.
Submit Biped.m and biped_demo.m Matlab files that, when run, produce the described plot (ie. stick figure plot of the biped as well plot of the torso, left foot and right foot frames, all relative to the torso frame).
