Journal of the Robotics Society of Japan

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This paper describes a stability of contact force control of an unmanned aerial vehicle (UAV), which has one DoF manipulator for bridge inspection: hammering and visual inspection. Impact force should be considered in modeling the contact condition between the UAV and the floor slab. The UAV was modeled as a one DoF slide manipulator in vertical direction because this paper focuses on contacting the floor slab. The impact force is modeled based on Hertzian contact stress following Fujita and Hattori's model. The objective is modeled as a elastic object: a spring-mass-damper system. Then the stability of the modeled condition is evaluated with Lyapunov's direct method. The control strategy of the UAV is cascade control separated into attitude control and position-force control; they are PID feedback loop. The force feedback is integrated into the position feedback seamlessly; the output of the force feedback is added to the desired position of the position feedback. Then an experiment of the contact force control is executed to assess the stability of the stability of the contact force control. The UAV could control the contact force with error 2.14π1.85[N] while the desired contact force was 15[N]. The UAV also could keep contacting the floor slab even if the UAV hammered the surface.

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Trajectory planning for humanoid robots requires satisfying various constraints such as balance, contact, joint limitation, kinematics, and collision. To obtain trajectory efficiently, related research has integrated coarse motion planning to fine full-body trajectory generation. In this paper, we propose a humanoid motion planner satisfying various constraints based on key pose generation by exploiting center-of-mass (COM) feasible region (CFR): (a) We show a method to project approximately balance constraints of statics and dynamics into CFR. (b) We propose a key pose generation capable of considering swing and support phase to satisfy asymptotically CFR constraint while satisfying kinematics constraints. (c) We show a method to obtain full-body trajectory by interpolating obtained key pose. We validate our proposed method through evaluations, in which the robot performs locomotion tasks related to ladder climbing under the stringent constraints, and experiments, in which the real robot achieves ladder motion.

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A planning method for helicopters cabled to a ground station is proposed avoiding contact between the cables and obstacles. Position of relay helicopter and length of cables are optimized in regard to total thrust required for the helicopters considering constraints with the penalty method. Example analyses of flying range with double and single helicopter systems are performed with the proposed method. Double-helicopter system has advantage compared to single-helicopter system in areas with low-ceiling and large depth or areas above convex obstacles. Experiments illustrate validity of the analyses.

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