Shady: A Robotic Sunshade
Carrick Detweiler, Alex Hornstein, Keith Kotay, Peter Osagie, Daniela
Rus, Paulina Varshavskaya, Iuliu Vasilescu,
Marsette A. Vona, Justin Werfel & Yeoreum Yoon
We work in the new Stata Center building in
a room with a large wall-window (about 4m tall and 8m wide) which currently
has no shades to block sunlight. As many of our desks are directly next
to this window we needed some means to block the light from hitting our
computer screens. Instead of traditional shades which would block the
whole window, detracting from the view, we have decided to build a robot
which can climb on the window's aluminum muntins.
It can thus be positioned on the window to be a localized sunshade and
will be able to dynamically track the sun throughout the day.
We are developing a four degree of freedom robot to climb around on
the lattice formed by the window muntins. The robot is symetric, with
two barrels that have a rotational degree of freedom, and each barrel
contains a one degree of freedom gripper which is able to grab onto a
muntin. Below is an image of the prototype.
Prototype of the four degree of freedom Shady robot with hand fan used
In addition to the four degrees of freedom used for motion, the robot
will also be able to deploy a hand fan as seen above. This will allow
the robot to move into the desired shading location with the minimum impact
on the aesthetics of the window. When it reaches the desired location
the shade can be deployed.
We are using a variety of hardware and electronics in the Shady prototype.
Most of the hardware has been custom designed. We are using a Sharp
Zaurus for high level control and interface the Zaurus with a stack
of Acroname Brainstems
for lower level sensing and motor control.
Planning and Control
Given a Shady robot and a system of muntins, we would like for Shady
to position itself in an optimal spot for shading. This requires the traversal
of the lattice formed by the muntins to goto and maintain the optimal
location which will possibly be changing as the outside lightning conditions
change. We developed a planning and control system that synthesizes the
primitive Shady steps needed to move from region A to region B on muntins.
We have implemented this in the Shady Simulator. This
allows us to test the algorithms we develop in simulation before using
them on the actual hardware. The simulator and hardware platform share
a large portion of the code base, allowing easy porting of algorithms.
One such algorithm we have developed is a Path Planner that finds the
shortest path from its current location to a desired goal point. Below
is a screen shot of the path finder.
Image showing all possible Shady gripper points in the environment within
a given search radius (light blue), the shortest path (red), and the goal
The user interacts with the planner by specifying a desired target point.
This is done in the simulator by clicking the mouse somewhere in the environment.
The path finder employs a breadth-first search to generate a graph representation
of the possible Shady gripper points in the environment. It then uses
Dijkstra's to find the shortest path given the selection of points. It
is interesting to note that it is possible that the path that gets Shady
closest to the desired point will not always be the shortest distance
path due to the kinematic structure of Shady. Furthermore, in environments
with muntins only intersecting at right angles, there are only a finite
number of points at which the barrel of a Shady can be attached.
Currently the planner is limited to 2D, however, it will be extended
in the future to work in arbitrary environments such as the 3D extension
of the Shady concept presented in .
We are also exploring ways in which Shadys can cooperate to improve
shading. If there are multiple locations that need to be shaded a group
of Shadys must decide which Shady should be assigned to which Shady location.
This planning process must take into consideration the fact that paths
my be blocked by other Shadys that are moving to a different shading location
or others that are actively shading. Additionally, there may be some situations
where multiple Shadys may be needed to shade a single location. In this
case care must be taken to avoid collisions. We are also exploring the
case where multiple Shadys can join together to form a unit modular self-reconfigurable
robot in .
NSF and Intel.
 Carrick Detweiler, Alex Hornstein, Keith Kotay, Peter
Osagie, Daniela Rus, Paulina Varshavskaya, Iuliu Vasilescu, Marsette A.
Vona, Justin Werfel, and Yeoreum Yoon. MultiShady: A Bipartite Heterogenous Unit Modular Self-Reconfigurable
Robot. In CSAIL Research Abstracts, 2005.