Performing Energy-Efficient Pick-and-Place Motions for High-Speed Robots by using Variable Stiffness Springs

Typically, for pick-and-place robots operating at high speeds, an enormous amount of energy is lost during the robot braking phase. This is due to the fact that, during such operational phase, most of the energy is dissipated as heat on the braking resistances of the motor drivers. In order to increase the energy-efficiency during the high-speed pick-and-place cycles, this paper investigates the use of variable stiffness springs (VSS) in parallel configuration with the motors. These springs store the energy during the braking phase, instead of dissipating it. The energy is then released to actuate the robot in a next displacement phase. This design approach is combined with a motion generator which seeks to optimize trajectories for input torques reduction (and thus of energy consumption), through solving a boundary value problem (BVP) based on the robot dynamics. Experimental results of the suggested approach on a five-bar mechanism show the drastic reduction of input torques, and therefore of energetic losses.

Dewatering fine solid suspension by using steam pressure filtration

Steam pressure filtration is the combination of mechanical and thermal in one equipment. This process shows the advantages in comparison to conventional pressure filtration by the characteristic of its distinction mechanism. Application of steam pressure filtration can be listed: dewatering the suspension of fine solid, remove the contaminant, dangerous chemical, dissolved ions, protecting the human health as well as the environment. This paper shows the mechanism of steam pressure filtration as well as the result of tests, the comparison related to the efficiency between steam pressure filtration and conventional pressure filtration. The steam pressure filtration shows the high efficiency in mechanical displacement phase in both input parameters: solid volume fraction of suspension and the height of filter cake. The residual moisture content and saturation of filter cake using steam pressure filtration are lower 10÷20% than those values of filter cake using conventional pressure filtration. Moreover, some preliminary tests taking account to the drying phase of steam pressure filtration are also showed. The moisture of fine material filter cakes is around 6÷13%. Through the result of tests, interpretation and discussion, the application of steam pressure filtration is possible in the field of mineral processing and metallurgy.

A Moving Target Velocity Estimation Method Based on the MC-MASA SAR Mode

Imaging position shift based on the multiple azimuth squint angles (MASA) mode is effective for target azimuth velocity estimation, whereas accuracy is low when target range velocity is high. In this paper, the estimation problem for both target azimuth and range velocities is considered based on the multi-channels MASA (MC-MASA) mode. Firstly, the acquisition geometry of MC-MASA mode and Doppler characteristics of a moving target are analyzed in detail, especially in squint mode. Then, for better moving target estimation, the stationary background clutter is removed using the displacement phase center antenna (DPCA) technique, and the failure in range velocity estimation with sequential SAR images is also discussed. Furthermore, a modified along-track interferometry (ATI) is proposed to preliminarily reconstruct the azimuth-and-range velocity map based on the MC-MASA mode. Since the velocity estimation accuracy is dependent on squint angle and signal-to-clutter ratio (SCR), the circumstances are divided into three cases with different iteration estimation strategies, which could expand the scene application scope of velocity estimation and achieve a high estimation accuracy along both azimuth and range directions. Finally, the performance of the proposed method is demonstrated by experimental results.

Intermittent Information-Driven Multi-Agent Area-Restricted Search

The problem is a two-dimensional area-restricted search for a target using a coordinated team of autonomous mobile sensing platforms (agents). Sensing is characterised by a range-dependent probability of detection, with a non-zero probability of false alarms. The context is underwater surveillance using a swarm of amphibious drones equipped with active sonars. The paper develops an intermittent information-driven search strategy, which alternates between two phases: the fast and non-receptive displacement phase (called the ballistic phase) with a slow displacement and sensing phase (called the diffusive phase). The proposed multi-agent search strategy is carried out in a decentralised manner, which means that all computations (estimation and motion control) are done locally. Coordination of agents is achieved by exchanging the data with the neighbours only, in a manner which does not require global knowledge of the communication network topology.

Characterization of the Effect of Exhaust Back Pressure on Crank Angle-Resolved Exhaust Exergy in a Diesel Engine

To enable efficient exhaust waste energy recovery (WER), it is important to characterize the exergy available in engine exhaust flows. In a recent article (Mahabadipour et al., 2018, Appl. Energy, 216, pp. 31–44), the authors introduced a new methodology for quantifying crank angle-resolved exhaust exergy (including its thermal and mechanical components) for the two exhaust phases, viz., the “blowdown” phase and the “displacement” phase. The present work combines experimental measurements with GT-SUITE simulations to investigate the effect of exhaust back-pressure (Pb) on crank angle-resolved exhaust exergy in a single-cylinder research engine (SCRE). To this end, Pb values of 1, 1.4, and 1.8 bar are considered for conventional diesel combustion on the SCRE. Furthermore, the effect of boost pressure (Pin) between 1.2 and 2.4 bar on the thermal and mechanical components of exhaust exergy is reported at different Pb. The exergy available in the blowdown and the displacement phases of the exhaust process is also quantified. Regardless of Pin, with increasing Pb, the cumulative exergy percentage in the blowdown phase reduced uniformly. For example, at Pin = 1.5 bar and 1500 rpm engine speed, the cumulative exergy percentage in the blowdown phase decreased from 34% to 17% when Pb increased from 1 bar to 1.8 bar. The percentage of fuel exergy available as exhaust exergy was quantified. For instance, this normalized cumulative exergy in the exhaust increased from 10% to 21% when Pb increased from 1 bar to 1.8 bar at 1200 rpm. Finally, although the present work focused on exhaust exergy results for diesel combustion in the SCRE, the overall methodology can be easily adopted to study exhaust exergy flows in different engines and different combustion modes to enable efficient exhaust WER.

Characterization of the Effect of Exhaust Back Pressure on Crank Angle-Resolved Exhaust Exergy in a Diesel Engine

To enable efficient exhaust waste energy recovery (WER), it is important to characterize the exergy available in engine exhaust flows. In a recent article (Mahabadipour et al. (2018), Applied Energy, Vol. 216, pp. 31–44), the authors introduced a new methodology for quantifying crank angle-resolved exhaust exergy (including its thermal and mechanical components) for the two exhaust phases, viz., the “blowdown” phase and the “displacement” phase. The present work combines experimental measurements with GT-SUITE simulations to investigate the effect of exhaust back-pressure (Pb) on crank angle-resolved exhaust exergy in a single-cylinder research engine (SCRE). To this end, Pb values of 1, 1.4, and 1.8 bar are considered for conventional diesel combustion on the SCRE. Furthermore, the effect of boost pressure (Pin) between 1.2 to 2.4 bar on the thermal and mechanical components of exhaust exergy are reported at different Pb. The exergy available in the blowdown and the displacement phases of the exhaust process are also quantified. Regardless of Pin, with increasing Pb, the cumulative exergy percentage in the blowdown phase reduced uniformly. For example, at Pin = 1.5 bar and 1500 rpm engine speed, the cumulative exergy percentage in the blowdown phase decreased from 34% to 17% when Pb increased from 1 bar to 1.8 bar. The percentage of fuel exergy available as exhaust exergy was quantified. For instance, this normalized cumulative exergy in the exhaust increased from 10% to 21% when Pb increased from 1 bar to 1.8 bar at 1200 rpm. Finally, although the present work focused on exhaust exergy results for diesel combustion in the SCRE, the overall methodology can be easily adopted to study exhaust exergy flows in different engines and different combustion modes to enable efficient exhaust WER.