A walking bipedal robot by adding passive springs like mono and biarticular muscles which correspond to rectus femoris (RF), biceps femoris (BF), gastrocnemius (GAS) and tibialis anterior (TA) in human legs has been modeled in this paper. The stability of human-like leg walking can be achieved by adding these passive springs in the leg mechanism of bipedal robot. On the other hand, using these springs may inflict a fatigue during walking due to the additional work that can provide to the joints. The main objective of this paper is to analyze the total work of the robot during walking by proposing four cases of the preload of the springs at the equilibrium position. It's found from this study that the case that has the most energy saving and ensure the comfortable walking to the robot is when the two muscles (GAS) and (TA) are not preloaded to support the total weight at the equilibrium position.
In recent years, the need for eco-friendly machining processes has increased dramatically in order to limit the excessive use of conventional cutting fluids, thereby reducing their negative effects on both environment and operator's health. In this context, dry cutting, minimum quantity lubrication (MQL) and nanofluid assisted MQL, as environmentally alternatives, have been positively shown their significance to overcome this problem. This experimental study was conducted from the perspective of performance analysis of machining characteristics in turning of AISI 304 austenitic stainless steel (ASS) under dry, MQL and nanofluids and hybrid nanofluids assisted MQL conditions with consideration of surface roughness (Ra), main cutting forces (Fc) and cutting temperature (T). In preparing the nanofluids, nano Molybdenum disulfide (MoS2), Multi-walled carbon nanotube (MWCNT) and nano graphene particles were added to the commercial vegetable cutting fluid as additives. Additionally, the effects of lubricating conditions on flank wear (VB) were investigated. In the end, statistical analysis, regression modeling and multi-criteria optimization based desirability function were performed. The results revealed that the Ra, Fc and T as well as VB were found to be lower with the use of nano graphene reinforced nanofluid assisted MQL followed by nano graphene/MoS2 reinforced hybrid nanofluid assisted MQL, MWCNT/MoS2 reinforced hybrid nanofluid assisted MQL, MWCNT reinforced nanofluid assisted MQL, nano MoS2 reinforced nanofluid assisted MQL and MQL, respectively, as compared to dry condition. Finally, it is worth mentioning that the nano graphene has the capability to perform as lubricant/coolant, thus contributing positively to the turning process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.