Figure 6 plots the spiking pattern and muscle activation signals of the retractor neuron-muscle unit from the body-coxa joint on the left-sided and right-sided middle legs, when the character turns left. With the activation dynamics (Equation 6), the discrete spiking signal is converted into a continuous activation stimulus. The result shows that when the character turns left, the number of spike trains on the left-sided leg is greater than the one on the right-sided leg. This leads to a larger activation signal for the muscle actuation. The result also shows that the coordination between different legs is achieved by preferably adjusting the number of spike trains, instead of the amplitude of the spike.Figure 6Spiking pattern and muscle activation of the neuron-muscle unit from the body-coxa joint on the left-sided and right-sided middle leg, when the character turns left. (a) Spiking pattern on the left leg. (b) Activation signal on the left leg. (c) Spiking pattern on the right leg. (d) Activation signal on the right leg.