A contribution to parallelization of symbolic robot models

SummaryThis paper is focused on task scheduling in multiprocessor robot controllers. To minimize the input-output time delay our consideration is restricted to parallel architectures that include complete crossbar interconnection networks. In this paper, an efficient scheduling algorithm based on a heuristic function is considered. This function takes into account delays caused by interprocessor communication and minimizes both the execution time and the communication cost. Robot control computation based on a highly efficient customized symbolic method is decomposed into a large number of simple tasks, each involving a single floating-point operation. Starting with an empty partial schedule, each step of the search extends the current partial schedule by adding one of the tasks yet to be scheduled. The heuristic function used in the algorithm actively directs the search for a feasible schedule, i.e. it helps choose the task that extends the current partial schedule. To increase the computational rate we introduced overlapping of computations.

Acquisition of Secondary Reinforcers by Children

In one partially reinforced and one continuously reinforced group, children made no response during training. One partially reinforced group picked up and ate candy which was presented contiguously with a light. One partially and one continuously reinforced group picked up the candy but did not eat it. One control group received no candy during training trials, and a second control group received no training. Extinction tests with the light contingent upon lever excursion indicated that a response during acquisition was not necessary to condition a secondary reinforcer, but strong effects were obtained by including a consummatory response. Stronger effects were obtained with a partial schedule and either no response or a consummatory response during acquisition trials.

Partial Reinforcement Effect under Odor Control

4 groups ( ns = 10) of albino rats were given 40 acquisition and 25 extinction trials in a straight runway under one of the following conditions: (1) continuous reinforcement with an exhaust fan operative; (2) continuous reinforcement with exhaust fan operating but blocked from exhausting; (3) partial reinforcement with exhaust fan operating but blocked, and (4) partial reinforcement with exhaust fan operative. The results imply that exhausting odor(s) under a partial schedule increases running speeds during acquisition and resistance to extinction. The study points to important methodological implications for partial reinforcement research.