Robotic manipulation with flexible link fingers

A robot manipulator is a spatial mechanism consisting essentially of a series of bodies, called "links", connected to each other at "joints". The joints can be of various types: revolute, rotary, planar, prismatic, telescopic or combinations of these. A serial connection of the links results in an open-chain manipulator. Closed-chain manipulators result from non-serial (or parallel) connections between links. Actuators at the joints of the manipulator provide power for motion. A robot is usually not designed for a very specific or repetitive task which can be done equally well by task-specific machines. Its strength lies in its ability to handle a range of tasks by virtue of being "re-programmable". Therefore, in addition to the mechanical hardware two other elements are integral to the description of a robot: sensors and control. With the advent of micro-electronics and digital computers the availability of sensors is ever increasing and the control is usually done by software executed by computers which also collect the sensory data. It is possible to model quite accurately, the dynamics of robot manipulators for purposes of control. However, for most practical robots the models are complex and numerically intensive to calculate in real-time. Traditional analyses of robot manipulators consider the whole mechanism to be rigid. Relaxation of the assumption of rigidity leads to further complication of the dynamics of the manipulator, leading to more difficulties in control. The overall motion of the manipulator is augmented by additional motion due to the dynamics of flexibility which must be considered. Sensing is also made more difficult. However, the ability to control robots with significant structural flexibilities, referred to as flexible robots in the rest of this thesis, influences robotics in many ways. It allows for consideration of new applications, observance of less conservative structural design and performance enhancements in certain classes of robotic tasks, which will be addressed in greater detail in the sections which follow

An Experimental Comparison of Tradeoffs in Using Compliant Manipulators for Robotic Grasping Tasks

Controllers developed for control of flexible-link robots in hybrid force-position control tasks by a new singular perturbation analysis of flexible manipulators are implemented on an experimental two-robot grasping setup. Performance criteria are defined for the grasping task. We present preliminary experimental data to show the tradeoffs between controller complexity and performance enhancement as we deal with greater flexibility. Various performance criteria are set up and experimental results are discussed within that setting. We conclude that large flexibility can be controlled and can lead to reasonable performances

A new method for accurate assessment of DNA quality after bisulfite treatment

The covalent addition of methylgroups to cytosine has become the most intensively researched epigenetic DNA marker. The vast majority of technologies used for DNA methylation analysis rely on a chemical reaction, the so-called ‘bisulfite treatment’, which introduces methylation-dependent sequence changes through selective chemical conversion of non-methylated cytosine to uracil. After treatment, all non-methylated cytosine bases are converted to uracil but all methylated cytosine bases remain cytosine. These methylation dependent C-to-T changes can subsequently be studied using conventional DNA analysis technologies. The bisulfite conversion protocol is susceptible to processing errors, and small deviation from the protocol can result in failure of the treatment. Several attempts have been made to simplify the procedure and increase its robustness. Although significant achievements in this area have been made, bisulfite treatment remains the main source of process variability in the analysis of DNA methylation. This variability in particular impairs assays, which strive for the quantitative assessment of DNA methylation. Here we present basic mathematical considerations, which should be taken into account when analyzing DNA methylation. We also introduce a PCR-based assay, which allows ab initio assessment of the DNA quality after bisulfite treatment and can help to prevent inaccurate quantitative measurement resulting from poor bisulfite treatment

Correlation between the results obtained from the quality control assays and PCR success from additional genomic targets of varying length

<p><b>Copyright information:</b></p><p>Taken from "A new method for accurate assessment of DNA quality after bisulfite treatment"</p><p></p><p>Nucleic Acids Research 2007;35(5):e29-e29.</p><p>Published online 26 Jan 2007</p><p>PMCID:PMC1865059.</p><p>© 2007 The Author(s).</p> The bar graphs in panel () and () show the results from the quality control assays similar to Figure 5. The QC assay indicates that incubation at 90°C limits amplification to only short amplicons

Box plot graphic depicting the variability of repeated measurements for each step in the process (Step 1: bisulphite treatment; Step 2: PCR; Step 3: MassCLEAVE; Step 4: MALDI-TOF MS analysis)

<p><b>Copyright information:</b></p><p>Taken from "A new method for accurate assessment of DNA quality after bisulfite treatment"</p><p></p><p>Nucleic Acids Research 2007;35(5):e29-e29.</p><p>Published online 26 Jan 2007</p><p>PMCID:PMC1865059.</p><p>© 2007 The Author(s).</p> Boxes are centered on the median and range from the lower to the upper quartile. Whiskers indicate the interquartile range. Red whiskers indicate the standard deviation from the mean. Bisulfite treatment and PCR can be identified as the greatest source of process variability. The post-PCR processing (MassCLEAVE) and, in particular, the MALDI analysis show high precision in repeated measurements

Gradient PAGE gel with CYBR Gold staining showing the DNA fragmentation of untreated genomic DNA (left) and after bisulfite treatment at varying temperatures (from left to right: 50, 70 and 80°C)

<p><b>Copyright information:</b></p><p>Taken from "A new method for accurate assessment of DNA quality after bisulfite treatment"</p><p></p><p>Nucleic Acids Research 2007;35(5):e29-e29.</p><p>Published online 26 Jan 2007</p><p>PMCID:PMC1865059.</p><p>© 2007 The Author(s).</p> The figure indicates that an increase of the incubation temperature during bisulfite treatment results in increased DNA fragmentation

Panel () shows the probability distributions for observed methylation ratios based on the binomial distribution and different amounts of starting molecules

<p><b>Copyright information:</b></p><p>Taken from "A new method for accurate assessment of DNA quality after bisulfite treatment"</p><p></p><p>Nucleic Acids Research 2007;35(5):e29-e29.</p><p>Published online 26 Jan 2007</p><p>PMCID:PMC1865059.</p><p>© 2007 The Author(s).</p> Shown are examples for 10, 25, 50 75 and 90% methylated molecules in the starting template. With a sample size of 3000 molecules, 95% of all randomly sampled probes will contain between 48 and 52% methylated DNA when the DNA sample contains 50% methylated DNA (red colored distribution). However, when the DNA sample contains only 300 molecules, this range is expanded from 43 to 57% (blue colored distribution). Panel () shows the 95% confidence intervals for sampling-means as a function of the number of the sampled molecules. Shown are results for 10 (blue), 25 (red) and 50% (black) methylated molecules in the starting template