Modeling Hydra Behavior Using Methods Founded in Behavior-Based Robotics

7.1. Generation of behaviors 37450400Latency vs. stimulus intensityMeasured dataFunction approximation350Reaction time [s]3002502001501005000 10 20 30 40 50 60 70 80 90 100Relative light intensity [%]Figure 7.7: Latency of response to light stimulus. In the function fitting, the measured responseto 6% relative stimulus intensity was considered an outlier.7.1.3 B3: Respond to light stimulusSimilar to B2, response occurs by contraction or by locomotion. As discussed in Section5.1.3, upon exposure to light, there is an immediate inhibition of any ongoing contraction.Following a latency which depend on stimulus intensity, a response is evoked. There isno habituation to repeated stimulus.Applicability clauseAs with B2, an event-driven AC was used. Activation of the AC occurs if M l > T l , whereT l was set to 0.2. The latency was modeled to fit the data obtained in [59]. Least squarefunction fitting was used, and the latency obtained wasL l = 24.15M l. (7.11)Fig. 7.7 illustrates the result obtained. Note that the measured data is a function of relativestimulus intensity in percent, whereas readings from the light sensor in the modeled Hydraare taken in [0, 1]. The activation threshold, T l , also ensures that division by zero does notoccur in the calculations of L l .