Error Analysis for the In-Situ Fabrication of Mechanisms

2003 ◽  
Vol 125 (4) ◽  
pp. 809-822 ◽  
Author(s):  
Sanjay Rajagopalan ◽  
Mark Cutkosky
Keyword(s):  
Error Analysis ◽  
Solid Freeform Fabrication ◽  
General Technique ◽  
Ongoing Research ◽  
Stochastic Error ◽  
In Situ Fabrication ◽  
Driver Error ◽  
Joint Clearances ◽  
Component Assembly

Fabrication techniques like Solid Freeform Fabrication (SFF), or Layered Manufacturing, enable the manufacture of completely pre-assembled mechanisms (i.e. those that require no explicit component assembly after fabrication). We refer to this manner of building assemblies as in-situ fabrication. An interesting issue that arises in this domain is the estimation of errors in the performance of such mechanisms as a consequence of manufacturing variability. Assumptions of parametric independence and stack-up made in conventional error analysis for mechanisms do not hold for this method of fabrication. In this paper we formulate a general technique for investigating the kinematic performance of mechanisms fabricated in-situ. The technique presented admits deterministic and stochastic error estimation of planar and spatial linkages with ideal joints. The method is illustrated with a planar example. Errors due to joint clearances, form errors, or other effects like link flexibility and driver-error, are not considered in the analysis—but are part of ongoing research.

Error Analysis for the In-Situ Fabrication of Mechanisms

2000 ◽  
Author(s):  
Puneet Goel ◽  
Sanjay Rajagopalan ◽  
Mark R. Cutkosky
Keyword(s):  
Error Analysis ◽  
Solid Freeform Fabrication ◽  
General Technique ◽  
Ongoing Research ◽  
Stochastic Error ◽  
In Situ Fabrication ◽  
Driver Error ◽  
Joint Clearances ◽  
Component Assembly

Abstract Fabrication techniques like Solid Freeform Fabrication (SFF), or Layered Manufacturing, enable the manufacture of completely pre-assembled mechanisms (i.e. those that require no explicit component assembly after fabrication). We refer this manner of building assemblies as in-situ fabrication. An interesting issue that arises in this domain is the estimation of errors in the performance of such mechanisms as a consequence of manufacturing variability. Assumptions of parametric independence and stack-up made in conventional error analysis for mechanisms do not hold for this method of fabrication. In this paper we formulate a general technique for investigating the kinematic performance of mechanisms fabricated in-situ. The technique presented admits deterministic and stochastic error estimation of planar and spatial linkages with ideal joints. However, only a planar example is illustrated in this paper. Errors due to joint clearances, or other effects like flexibility and driver-error, are not considered in the analysis — but are part of ongoing research.

Optimal Pose Selection for In-Situ Fabrication of Planar Mechanisms

1999 ◽  
Author(s):  
Sanjay Rajagopalan ◽  
Mark R. Cutkosky
Keyword(s):  
Solid Freeform Fabrication ◽  
Link Length ◽  
Planar Mechanisms ◽  
Freeform Fabrication ◽  
In Situ Fabrication ◽  
Tolerance Region ◽  
Ongoing Work ◽  
Task Requirements ◽  
The Difference

Abstract Solid Freeform Fabrication (SFF) techniques allow the in-situ fabrication of fully-assembled devices with mating/fitting parts. Recently, this technique of fabrication has been found to be useful for building integrated mechanisms in robotics, and a wide array of other similar applications are anticipated. An interesting issue that arises during the fabrication of such mechanisms is the determination of an optimal pose in which the mechanism should be built. For example, should the mechanism be built in a folded or stretched-out position? In conventional manufacturing these issues do not arise, as each individual link is typically manufactured separately and then the pieces are brought together during assembly. In this paper, we address the issue of finding a preferred (or optimal) pose for in-situ fabrication of planar mechanisms. There are many factors (e.g. achievable tolerances, non-interference, workspace size limitations, thermal considerations etc.) which can determine the suitability of a candidate build pose so that pre-specified task requirements are met. We limit our analysis to finding the optimal build configuration given achievable (in general, non-homogeneous, anisotropic) accuracy on joint position. For this treatment, we also make the simplifying assumption that the task requirements can be best satisfied by minimizing variability of link-lengths. Alternate task requirements, for example, maintaining end-point accuracy within a tolerance region, are being considered as part of ongoing work. We cast the problem of minimizing variability in link length as that of determining the relative position of two location tolerance regions for which the difference between their extremal distances is at a minimum (i.e., as they undergo constrained relative motion in the Euclidean plane). The method is similar to computational geometry techniques that have been developed in pattern matching and robot motion planning, with some important differences. We present some example mechanisms and their optimal pose under given workspace configurations.

scholarly journals Rapid mechanochemical synthesis of polyanionic cathode with improved electrochemical performance for Na-ion batteries

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xing Shen ◽  
Quan Zhou ◽  
Miao Han ◽  
Xingguo Qi ◽  
Bo Li ◽  
...  
Keyword(s):  
Energy Storage ◽  
Electrochemical Performance ◽  
Mechanochemical Synthesis ◽  
Cathode Materials ◽  
Industrial Application ◽  
Synthesis Process ◽  
In Situ Fabrication ◽  
Stationary Energy ◽  
Carbon Coated

AbstractNa-ion batteries have been considered promising candidates for stationary energy storage. However, their wide application is hindered by issues such as high cost and insufficient electrochemical performance, particularly for cathode materials. Here, we report a solvent-free mechanochemical protocol for the in-situ fabrication of sodium vanadium fluorophosphates. Benefiting from the nano-crystallization features and extra Na-storage sites achieved in the synthesis process, the as-prepared carbon-coated Na3(VOPO4)2F nanocomposite exhibits capacity of 142 mAh g−1 at 0.1C, higher than its theoretical capacity (130 mAh g−1). Moreover, a scaled synthesis with 2 kg of product was conducted and 26650-prototype cells were demonstrated to proof the electrochemical performance. We expect our findings to mark an important step in the industrial application of sodium vanadium fluorophosphates for Na-ion batteries.

In-situ fabrication of novel flower like MoS2/CoTiO3 nanorod heterostructures for the recyclable degradation of Ciprofloxacin and bisphenol A under sunlight

Chemosphere ◽  
2021 ◽  
pp. 130822
Author(s):  
Ramakrishna Dadigala ◽  
Rajkumar Bandi ◽  
Madhusudhan Alle ◽  
Bhagavanth Reddy Gangapuram ◽  
Veerabhadram Guttena ◽  
...  
Keyword(s):  
Bisphenol A ◽  
In Situ Fabrication

scholarly journals In Situ Fabrication of Activated Carbon from a Bio-Waste Desmostachya bipinnata for the Improved Supercapacitor Performance

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Gopal Krishna Gupta ◽  
Pinky Sagar ◽  
Sumit Kumar Pandey ◽  
Monika Srivastava ◽  
A. K. Singh ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Energy Density ◽  
Power Density ◽  
Supercapacitor Electrode ◽  
In Situ Fabrication ◽  
Transmission Electron ◽  
Good Energy ◽  
Supercapacitor Performance ◽  
Operating Potential

AbstractHerein, we demonstrate the fabrication of highly capacitive activated carbon (AC) using a bio-waste Kusha grass (Desmostachya bipinnata), by employing a chemical process followed by activation through KOH. The as-synthesized few-layered activated carbon has been confirmed through X-ray powder diffraction, transmission electron microscopy, and Raman spectroscopy techniques. The chemical environment of the as-prepared sample has been accessed through FTIR and UV–visible spectroscopy. The surface area and porosity of the as-synthesized material have been accessed through the Brunauer–Emmett–Teller method. All the electrochemical measurements have been performed through cyclic voltammetry and galvanometric charging/discharging (GCD) method, but primarily, we focus on GCD due to the accuracy of the technique. Moreover, the as-synthesized AC material shows a maximum specific capacitance as 218 F g−1 in the potential window ranging from − 0.35 to + 0.45 V. Also, the AC exhibits an excellent energy density of ~ 19.3 Wh kg−1 and power density of ~ 277.92 W kg−1, respectively, in the same operating potential window. It has also shown very good capacitance retention capability even after 5000th cycles. The fabricated supercapacitor shows a good energy density and power density, respectively, and good retention in capacitance at remarkably higher charging/discharging rates with excellent cycling stability. Henceforth, bio-waste Kusha grass-derived activated carbon (DP-AC) shows good promise and can be applied in supercapacitor applications due to its outstanding electrochemical properties. Herein, we envision that our results illustrate a simple and innovative approach to synthesize a bio-waste Kusha grass-derived activated carbon (DP-AC) as an emerging supercapacitor electrode material and widen its practical application in electrochemical energy storage fields.

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