9,215 research outputs found
Role of friction-induced torque in stick-slip motion
We present a minimal quasistatic 1D model describing the kinematics of the
transition from static friction to stick-slip motion of a linear elastic block
on a rigid plane. We show how the kinematics of both the precursors to
frictional sliding and the periodic stick-slip motion are controlled by the
amount of friction-induced torque at the interface. Our model provides a
general framework to understand and relate a series of recent experimental
observations, in particular the nucleation location of micro-slip instabilities
and the build up of an asymmetric field of real contact area.Comment: 6 pages, 5 figure
Automatic polishing process of plastic injection molds on a 5-axis milling center
The plastic injection mold manufacturing process includes polishing
operations when surface roughness is critical or mirror effect is required to
produce transparent parts. This polishing operation is mainly carried out
manually by skilled workers of subcontractor companies. In this paper, we
propose an automatic polishing technique on a 5-axis milling center in order to
use the same means of production from machining to polishing and reduce the
costs. We develop special algorithms to compute 5-axis cutter locations on
free-form cavities in order to imitate the skills of the workers. These are
based on both filling curves and trochoidal curves. The polishing force is
ensured by the compliance of the passive tool itself and set-up by calibration
between displacement and force based on a force sensor. The compliance of the
tool helps to avoid kinematical error effects on the part during 5-axis tool
movements. The effectiveness of the method in terms of the surface roughness
quality and the simplicity of implementation is shown through experiments on a
5-axis machining center with a rotary and tilt table
Computing push plans for disk-shaped robots
Suppose we want to move a passive object along a given path, among obstacles in the plane, by pushing it with an active robot. We present two algorithms to compute a push plan for the case that the obstacles are non-intersecting line segments, and the object and robot are disks. The first algorithm assumes that the robot must maintain contact with the object at all times, and produces a shortest path. There are also situations, however, where the robot has no choice but to let go of the object occasionally. Our second algorithm handles such cases, but no longer guarantees that the produced path is the shortest possible
Desktop fiber push-out apparatus
A desktop fiber push-out was developed which offers the advantage of being compact, easy to operate, and inexpensive. A description of the design and operation of this apparatus is given
Customer Focus Newsletter, May - June, 2011, Vol. 8, no. 3
A bi-monthly bulletin to keep the department/agency management teams of state government better informed. We hope to consolidate most of the service update messages we send throughout the month and keep you updated about the work of the Customer Councils.
If yours is one of the many departments who participated in the second
annual DAS customer satisfaction survey recently, we thank you for taking
the time to give us this important feedback. We look forward to sharing
survey results with you, and pledge to consider responses carefully as we
work to determine benchmarks and set future priorities
Nonprehensile Dynamic Manipulation: A Survey
Nonprehensile dynamic manipulation can be reason- ably considered as the most complex manipulation task. It might be argued that such a task is still rather far from being fully solved and applied in robotics. This survey tries to collect the results reached so far by the research community about planning and control in the nonprehensile dynamic manipulation domain. A discussion about current open issues is addressed as well
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