bots IN BRIEF
16 SERVO 07.2016
Not sure how to dispose of your
trash properly? Not
sure what goes in
the recycle bin or
Well, that is a
Clean Robotics is
trying to fix with its
trash robot. The
robotic system uses
motion sensors to
approaching and flipping open a lid; load sensors to
know when something is tossed into the bin; and metal
detectors and a machine vision system that analyzes the
objects to help determine whether they are recyclable
or landfill material. When it makes its decision, a simple
system of trap doors and tilting motors directs the
discarded object into the right bin.
The company admits that the robot’s $5,000 price
tag is a bit steep, but argues that some municipalities are
already purchasing $4,000 smart trash systems that
don’t do much besides report when they are full. So, it’s
not that crazy.
NEED AN EXTRA ARM? ZIP IT!
As useful as robot arms are, they tend to be heavy bulky things that need a bunch of support and structure to get
them to work properly. If you need precision and speed, this
may be unavoidable, but if all you’re looking for is long reach,
a high strength-to-weight ratio, and very low cost (which,
admittedly, are a lot of things to be looking for), another
option is available from researchers at the University of
Pennsylvania: an arm made out of a strip of plastic that zips
together with itself, creating an extendable cylinder that can
be paired with winches and cables, and used for manipulation.
This concept is similar in principle to some commercially
available systems like the Zippermast and Spiralift, but both of
those designs are heavier and significantly more complicated.
The spiral zipper uses a single band that’s made of very
lightweight plastic, with a relatively simple meshing mechanism
that meshes the teeth on the bottom edge of one wrap with
the teeth on the top of the wrap below to create a cylinder
that has a very high strength-to-weight ratio, with
exceptionally good compressive performance. Changing the
length of the arm is as simple as zipping or unzipping the band;
it’s completely reversible, and you can stow the arm almost
entirely in a very small volume consisting of the plastic band
spooled around the zipping mechanism.
The spiral zipper only creates the structure of the arm.
There’s no integrated actuation besides the extension and
retraction that you get from zipping or unzipping the arm on
demand. The researchers envision mounting the base of the
arm on a gimbal, with a 3-DOF wrist on the end of it to
create a 6-DOF system.
Since the arm isn’t particularly stiff (especially when
moving), it doesn’t make sense to actuate it with motors from
the base. Instead, winches mounted on the base with tethers
connected to the end of the arm could be used to control its
motion, which makes sure that the predominant force on the
tube is compression (what the structure is good at).
In terms of applications, there’s a lot of potential for a
system with such a high strength-to-weight ratio that can pack
down into a very small size. For example, the US Army is
interested in mounting the arm on an octorotor being
developed at the Army Research Laboratory, and the
researchers are also planning on trying the arm out on indoor
mobile robots as aids for the elderly.
The arm could also “enable the manipulation of large
objects such as furniture.” It seems like this design would lend
itself to space applications, where efficiency in weight and
volume are such a priority.