Terrestrial animals transition between locomotor modes to move through complex 3-D terrain. For example, to traverse grass-like beam obstacles, the discoid cockroach often transitions from pushing across the beams with body pitching (the pitch mode) to rolling into a beam gap (the roll mode). Our recent study (Othayoth, Thoms, Li, 2020, PNAS) discovered that kinetic energy fluctuation of body oscillation due to self-propulsion helps a robotic physical model overcome a barrier on a potential energy landscape to make pitch-to-roll transition. Although the animal also displayed substantial kinetic energy fluctuation, it was not sufficient to explain the observed pitch-to-roll transition. Besides body oscillation, during beam interaction the animal also flexed its head and abdomen and used its left and right hind legs differentially (Wang, Othayoth, Li, 2019, SICB). Here, we hypothesized that head and body flexion reduces the pitch-to-roll transition barrier. To test this, we measured the animal’s head and abdomen flexion (N = 3 individuals, n = 36 trials) and modeled how they changed the potential energy landscape reconstructed from the measured body and beam motions. However, we found that pitch-to-roll barrier did not change significantly with head and abdomen flexion (P > 0.05, ANOVA). Alternatively, the animal may be flexing its head against the obstacles to feel their resistance and use this information to guide abdomen and leg motions to facilitate transition. To study this, we developed a new robot with an actuated head and abdomen that can flex and a force sensor in the head to measure terrain contact forces. The robot also has underactuated body pitch and roll control to simulate the effect of legs. We are developing sensory feedback control and will use the robot to perform systematic experiments.