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Multi-robot teams have been shown to be effective in accomplishing complex tasks which require tight coordination among team members. In homogeneous systems, recent work has demonstrated that “stepping stone” rewards are an effective way to provide agents with feedback on potentially valuable actions even when the agent-to-agent coupling requirements of an objective are not satisfied. In this work, we propose a new mechanism for inferring hypothetical partners in tightly-coupled, heterogeneous systems called Dirichlet-Multinomial Counterfactual Selection (DMCS). Using DMCS, we show that agents can learn to infer appropriate counterfactual partners to receive more informative stepping stone rewards by testing in a modified multi-rover exploration problem. We also show that DMCS outperforms a random partner selection baseline by over 40%, and we demonstrate how domain knowledge can be used to induce a prior to guide the agent learning process. Finally, we show that DMCS maintains superior performance for up to 15 distinct rover types compared to the performance of the baseline which degrades rapidly.

High leakage currents in deep sub micron regimes are becoming a major contributor to total power dissipation of CMOS circuits as the threshold voltage, channel length and gate oxide thickness are scaled. Consequently, identification and modelling of different leakage components is very important for estimation and reduction of leakage power, especially for low power applications. In this work the impact of gate leakage on SRAM is described and two approaches for reducing gate leakage currents are examined in detail. In one approach, the supply voltage is reduced while in the other the potential of the ground node is raised. In both the approaches the effective voltage across SRAM cell is reduced in inactive mode using a dynamic self-controllable switch. CADENCE Simulations are performed with 180nm CMOS technology process file and the leakage currents of all the cells are measured and compared. Simulation results revealed that there is a significant reduction in leakage current for this proposed cell with the SVL circuit reducing the supply voltage.