SnakeBot

To create a robot with arbitrary DOF, the SnakeBot can be used.

The SnakeBot consists of n linkages, where n is a parameter passed to the constructor of the robot. Here, we assume each link has uniform mass distribution.

In the figure above, the \(i\)-th link consists of mass \(m_i\) and length \(l_i\).

Initial Configuration and Joint Parameters

Below, the robot in initial configuration with stationary coordinate frame \(\{S\}\) and origin \(\{O\}\) is shown:

Joint	Type	Point on Joint Twist Axis (m)	Joint Direction	Joint Twist
J1	Rev. (1)	(0, 0, 0)	(0, 0, 1)	(1, 0, 0, 0, 0, 0)
J2	Rev. (1)	(\(l_1\), 0, 0)	(0, 0, 1)	(0, \(-l_1\), 0, 0, 0, 1)
J3	Rev. (1)	(\(l_1+l_2\), 0, 0)	(0, 0, 1)	(0, \(-l_1-l_2\), 0, 0, 0, 1)
\(\vdots\)	\(\vdots\)	\(\vdots\)	\(\vdots\)	\(\vdots\)
Jn	Rev. (1)	(\(\sum_{i=1}^{n-1}l_i\), 0, 0)	(0, 0, 1)	(0, \(-\sum_{i=1}^{n-1}l_i\), 0, 0, 0, 1)

Example code

To construct a 5-DOF SnakeBot, run the following code:

% Geometric and Inertial Parameters of SnakeBot
nq = 5;         % The number of linkages of the Snakebot
m  = 1;         % The   mass of the each link
l  = 1;         % The length of the each link

m_arr = m * ones( 1, nq );  % The mass   array to construct SnakeBot
l_arr = l * ones( 1, nq );  % The length array to construct SnakeBot

% Construct a 5-DOF SnakeBot
robot = SnakeBot( nq, m_arr, l_arr );
robot.init( )

% Attach the 5-DOF SnakeBot to animation for visualization
anim = Animation( 'Dimension', 2, 'xLim', [-1.5,6.5], 'yLim', [-4,4] );
anim.init( )
anim.attachRobot( robot )

The output figure should look like this: