Video Friday: Walking on Ceilings, Cat-Inspired Legs, and Robot Grasps Tofu

The 2015 IEEE International Conference on Intelligent Robots and Systems (IROS) ends today in Hamburg, Germany, and we’ve heard that some 2,500 people attended the talks and visited the exhibit hall. That’s yooooge, as one U.S. presidential candidate would put it.

We’ve started to post some of the most interesting stuff, but there will be lots more in-depth IROS posts for you over the next several weeks. Right now we’re preparing for ROSCon, which starts tomorrow, so for Video Friday today we selected some of our favorite videos presented at the conference. Enjoy!

“3D Printed Soft Skin for Safe Human-Robot Interaction,” by Joohyung Kim, Alexander Alspach, and Katsu Yamane, from Disney Research, Pittsburgh, Pa.

The purpose of this research is the development of a soft skin module with a built-in airtight cavity in which air pressure can be sensed. A pressure feedback controller is implemented on a robotic system using this module for contact sensing and gentle grasping. The soft skin module is designed to meet size and safety criteria appropriate for a toy- sized interactive robot. All module prototypes are produced using a muti-material 3D printer. Experimental results from collision tests show that this module significantly reduces the impact forces due to collision. Also, using the measured pressure information from the module, the robotic system to which these modules are attached is capable of very gentle physical interaction with soft objects.

“Walking Inverted on Ceilings With Wheel-Legs and Micro-structured Adhesives,” by William A. Breckwoldt, Kathryn A. Daltorio, Lars Heepe, Andrew D. Horchler, Stanislav N. Gorb, and Roger D. Quinn, from Case Western Reserve University, Cleveland, Ohio, and Kiel University, Kiel, Germany.

Gecko-inspired structured adhesives will be valuable for novel climbing and space robots. Robots also provide useful evaluation platforms for these adhesives. Climbing robots need to be lightweight, and thus many designs use multiple feet on a single rotating wheel-leg. Generally, such designs have not been able to walk robustly on steeper than vertical substrates. In this work, we use an improved version of our previous Mushroom-Shaped Adhesive MicroStructured (MSAMS) tape to support a power-autonomous robot reliably walking inverted on glass ceilings. The resulting speeds are greater than one body/length per second, faster than other adhesion-based climbing prototypes. The printed robot design is also a contribution toward future robotic designs and will have future applications in testing new adhesives for robotic feet.

“Development of Robot Legs Inspired by Bi-articular Muscle-Tendon Complex of Cats,” by Ryuki Sato, Ichiro Miyamoto, Keigo Sato, Aiguo Ming, and Makoto Shimojo, from University of Electro-Communications, Tokyo, Japan.

Within the limbs of typical animals, there exist bi-articular muscles crossing two joints. It is known that the bi-articular muscles of the felid play an important role in the locomotion. Also the muscle-tendon complex, composed of the gastrocnemius muscle and the Achilles’ tendon that cross the knee joint and the ankle joint contributes much to the movements such as running and jumping particularly. Besides, because the muscle-tendon complex has the function for absorbing shocking, it is utilized for soft landing from high places. To achieve high performance for jumping and landing motion like cats, we are developing robot legs inspired by the bi-articular muscle-tendon complex of cats. The leg consists of hip, knee and ankle joints. For the knee and ankle joints, a four-bar linkage mechanism with one elastic linkage, in which the knee joint is driven by an electric rotary motor and the ankle joint is passive, is applied. By this mechanism, basic functions of the bi-articular muscle-tendon complex of felids like cats can be realized and the performance for jumping and landing can be improved. In this paper, the new leg mechanism is described. Moreover, a prototype of a pair of the hind legs of the quadruped robot using the new mechanism has been developed. The results of jumping and landing experiments are shown to validate the effectiveness of the mechanism.

“Study of Swing-Grouser Wheel: A Wheel for Climbing High Steps, Even in Low Friction Environment,” by Hirotaka Komura, Hiroya Yamada, Shigeo Hirose, Gen Endo, and Koichi Suzumori, from Tokyo Institute of Technology and Hibot, Tokyo, Japan.

Generally, wheel mechanisms are inferior to a tracked or walking mechanism in terms of step climbability or traversability in rough terrain; however, they are superior in terms of energy efficiency, structural simplicity, and carrying capacity. This paper proposes a new wheel mechanism, the swing-grouser wheel, which can climb high steps (especially in low friction environments) and has high energy efficiency. In addition, the swing-grouser wheel can climb regardless of the body inclination. Its merits are compared to the results of prior studies. Furthermore, the performance of the swing- grouser wheel was confirmed using a real device experiment and a 2D physics simulation, and improved using a full search of the parameters of the swing-grouser wheel. As a result, one improved parameter resulted in climbing at over 68% of the wheel diameter in a low friction environment; additionally, the energy efficiency was better than that of the previous model.

“The Tri-Wheel: A Novel Wheel-Leg Mobility Concept,” by Lauren M. Smith, Roger D. Quinn, Kyle A. Johnson, and William R. Tuck, from Northrop Grumman, San Diego, Calif., Case Western Reserve University, Cleveland, Ohio, NASA Glenn Research Center, Cleveland, Ohio, and Jacobs Technology.

The Tri-Wheel is a novel wheel-leg locomotion concept inspired by work with first responders. Through its two modes of operation—Driving Mode and Tumbling Mode— this mechanism is able to both drive quickly on smooth surfaces at roughly 1.7 times desired speed and climb objects as tall as 67% of the diameter of the mechanism. The unique gearing configuration that facilitates these dual capabilities is described, and testing quantifies that this nonprecision gearing system is roughly 81% efficient in a worst-case scenario of loading. This work introduces the Tri-Wheel concept and provides preliminary testing to validate its predicted operating characteristics.

“HippoCampus: A Micro Underwater Vehicle for Swarm Applications,” by Axel Hackbarth, Edwin Kreuzer, and Eugen Solowjow, from Hamburg University of Technology, Germany.

The HippoCampus platform is a low-cost micro autonomous underwater vehicle for swarm robotics research. This paper presents the hardware and software design, the communication link, instrumentation, and control system. The quadrotor design enables the vehicle to perform agile maneu- vers in a very confined test tank. Vehicle navigation is based on the on-board sensor suite. Autonomous path following is presented and experimental results are evaluated.

“Inverse Kinematics and Reflex Based Controller for Body-limb Coordination of a Salamander-Like Robot Walking on Uneven Terrain,” by Tomislav Horvat, Konstantinos Karakasiliotis, Kamilo Melo, Laura Fleury, Robin Thandiackal, and Auke J. Ijspeert, from Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland. 

Search and rescue (SAR) missions are being car- ried out by several types of robots. They include ground, marine and air vehicles depending on the terrain and mission to be tackled. A particular niche for SAR activities are shallow waters. They present high difficultly for conventional ground or marine robots because of the mix of water and ground. Such an environment is difficult to be accessed for a robot without some built-in amphibious capabilities. Our lab has experience in the design of amphibious salamander-like robots. In order to consider whether these robots would be suited for SAR missions in shallow waters, a key requirement is the ability to tackle rough terrains. In this paper we present a control framework for a highly redundant salamander-like robot. It involves bio- inspired spine control, inverse kinematics-based limb control, proper limb-spine coordination, reflex mechanisms and attitude control. The framework is validated in a simulation and on the real robot. In both cases, the robot is used in two different configurations: with and without its tail, in order to investigate how the tail (which is necessary for swimming) affects ground locomotion. With this exploration, we aim to set the precedent for improving the problem of dynamic locomotion of salamander-like robots over unperceived rough terrain. Our results confirm that the design of reflexes like stumbling and extension, combined with an attitude controller, allows for the improving of the performance of the robot in a generic rough terrain which includes stairs, holes and bumps with several levels of complexity adjusted according to the robot dimensions.

“User Modelling for Personalised Dressing Assistance by Humanoid Robots,” by Yixing Gao, Hyung Jin Chang, and Yiannis Demiris, from Imperial College London, United Kingdom.

Assistive robots can improve the well-being of disabled or frail human users by reducing the burden that activities of daily living impose on them. To enable personalised assistance, such robots benefit from building a user-specific model, so that the assistance is customised to the particular set of user abilities. In this paper, we present an end-to-end approach for home-environment assistive humanoid robots to provide personalised assistance through a dressing application for users who have upper-body movement limitations. We use randomised decision forests to estimate the upper-body pose of users captured by a top-view depth camera, and model the movement space of upper-body joints using Gaussian mixture models. The movement space of each upper-body joint consists of regions with different reaching capabilities. We propose a method which is based on real-time upper-body pose and user models to plan robot motions for assistive dressing. We validate each part of our approach and test the whole system, allowing a Baxter humanoid robot to assist human to wear a sleeveless jacket.

“Aerial Tool Operation System Using Quadrotors as Rotating Thrust Generators,” by Hai-Nguyen Nguyen, Sangyul Park, and Dongjun Lee, from Seoul National University, Seoul, South Korea.

We propose a new aerial tool operation system consisting of multiple quadrotors connected to a tool by spherical joints to perform tool operation tasks. We model the system and show that the attitude dynamics of each quadrotor is decoupled from the tool dynamics, so that we can consider the quadrotors as thrusters and control the tool by adjusting the orientation and magnitude of these thrusters. We also show that the 6-DOF tool dynamics could be under-actuated or fully- actuated, depending on the number of quadrotors attached to the tool and the geometric configuration of their attachments. We then design control laws for the tool-tip position/orientation tracking of the (under-actuated) tool system with two quadro- tors and the (fully-actuated) tool system with three quadrotors. We use Lyapunov approach to find the desired thrust command for each quadrotor while also taking into account the spherical joint limits in a form of constrained optimization. Simulation and implementation results are performed to support the theory.

“High-Speed, Steady Flight With a Quadrocopter in a Confined Environment Using a Tether,” by Maximilian Schulz, Federico Augugliaro, Robin Ritz, and Raffaello D’Andrea, from ETH Zurich, Switzerland.

This paper presents a method that enables high-speed, steady flight in confined spaces for tethered quadro- copters. Thanks to the centripetal force exerted by the tether, high-speed trajectories along circles at different velocities, accelerations, and orientations in space can be flown. Various circular maneuvers are experimentally demonstrated, and tangential velocities of up to 15 m/s and centripetal accelerations of more than 13g can be achieved in steady flight. The recorded data allows to characterize the flight behavior of quadrocopters at high airspeeds: As an example, an estimate of the actual thrust produced by the motors and of the aerodynamic drag acting on the vehicle is presented. An accompanying video shows tethered quadrocopters performing high-speed maneuvers.

“In-air Knotting of Rope by a Dual-arm Multi-finger Robot,” by Shunsuke Kudoh, Tomoyuki Gomi, Ryota Katano, Tetsuo Tomizawa, and Takashi Suehiro, from University of Electro-Communications, Tokyo, Japan.

In the present paper, we propose a method for in-air knotting by a dual-arm, multi-finger robot. Most previous studies about knotting by robots assume that the rope is placed on a table. However, in-air knotting requires more skillful hand manipulations, such as swapping ropes between the right and left hands. Therefore, we herein focus on hand motion and first extract the essential hand motions for knotting, referred to herein as skill motions, by observing human knotting procedures. Next, hardware with the capability of executing these skill motions is developed. Finally, experiments are conducted to confirm that several types of knots can be tied in the air using the proposed method.

“Knot-Tying With Flying Machines for Aerial Construction,” by Federico Augugliaro, Emanuele Zarfati, Ammar Mirjan, and Raffaello D’Andrea, from ETH Zurich, Switzerland.

This paper addresses one of the fundamental tasks for the aerial assembly of tensile structures: aerial knot-tying. It presents a framework for representing and realizing knots with flying machines. A suitable representation of the knot topology is introduced taking into account the use of supporting elements and the characteristics of flying machines. This information is then translated into three-dimensional trajectories for the vehicle performing the aerial knot-tying task. Furthermore, preliminary results suggest that the quality of the resulting knot can be improved by the use of an iterative learning algorithm. Experiments are performed with quadrocopters to validate the proposed approach. An accompanying video shows the aerial knot-tying process.

“Dynamic Trotting on Slopes for Quadrupedal Robots,” by Christian Gehring, C. Dario Bellicoso, Stelian Coros, Michael Bloesch, Peter Fankhauser, Marco Hutter, and Roland Siegwart, from ETH Zurich, Switzerland, and Carnegie Mellon University.

Quadrupedal locomotion on sloped terrains poses different challenges than walking in a mostly flat environment. The robot’s configuration needs to be explicitly controlled in order to avoid slipping and kinematic limits. To this end, information about the terrain’s inclination is required for carefully planning footholds, the pose of the main body, and modulation of the ground reaction forces. This is even more important for dynamic trotting, as only two support legs are available to compensate for gravity and drive a desired motion. We propose a reliable method for estimating the parameters of the terrain quadrupedal robots move on, in the face of limited perception capabilities and drifting robot pose estimates. By fusing inertial measurements, kinematic data from joint encoders and contact information from force sensors, the local inclination can be robustly estimated and used to optimize the contact forces to reduce slippage. The estimated terrain information, namely the pitch and roll angles of the ground plane, is exploited in an extended version of our previous model- based control approach. Our improved control framework enabled StarlETH, a medium-sized, fully autonomous, torque- controllable quadrupedal robot, to trot on slopes of up to 21◦.

“Wind Disturbance Rejection for an Insect-Scale Flapping-Wing Robot,” by Pakpong Chirarattananon, Kevin Y. Ma, Richard Cheng, and Robert J. Wood, from City University of Hong Kong, Hong Kong, Harvard University, Cambridge, Mass., and Princeton University, Princeton, N.J. 

Despite having achieved unconstrained stable flight, the insect-scale flapping-wing robot is still tethered for power and control. Towards the goal of operating a biologically- inspired robot autonomously outside of laboratory conditions. In this paper, we simulate outdoor disturbances in the lab- oratory setting and investigate the effects of wind gusts on the flight dynamics of a millimeter-scale flapping wing robot. Simplified models describing the disturbance effects on the robot’s dynamics are proposed, together with two disturbance rejection schemes capable of estimating and compensating for the disturbances. The proposed methods are experimentally verified. The results show that they reduced the root mean square position errors by approximately 50% when the robot was subject to 60 cm·s⁻¹ horizontal wind.

“Robotic Origami Folding With Dynamic Motion Primitives,” by Akio Namiki and Shuichi Yokosawa, from Chiba University, Chiba, Japan.

Paper folding is one of the most difficult tasks for multi-fingered robot hands because paper is deformable and its stiffness distribution is nonuniform. In this study, we aimed to achieve dexterous paper folding by extracting some dynamic motion primitives. Each primitive contains visual or force information, a physical model of a sheet of paper is used for analyzing its deformation, and a machine learning method is used for predicting its future state. We also propose a strategy for achieving valley folds in a sheet of paper twice in a row. One problem faced in folding paper is that, in the second fold, the crease line of the first fold disturbs the folding accuracy. We propose some new manipulation techniques to solve this problem. Finally, we show some demonstrations of paper folding achieved with a high success rate.

“Dual Connected Bi-Copter With New Wall Trace Locomotion Feasibility That Can Fly at Arbitrary Tilt Angle,” by Koji Kawasaki, Yotaro Motegi, Moju Zhao, Kei Okada, and Masayuki Inaba, from University of Tokyo, Japan.

We have developed a robot with a new control mechanism in order to collect information on flying robots in multiple fields. We aimed for a function that could rotate the tilt angle continuously and without limit and a function for flying maintaining any desired tilt angle with a structure that could efficiently use the thrust generated by the propellers. We devised a mechanism that connected two bicopter modules, each of which combines two of the four propellers into one set and named this mechanism the  Bi Copter. This mechanism provided movements including landing, take-off, and flying with any desired tilt angle. This ability of this mechanism to fly walls with continuously changing surface angles and full 360 spherical coverage makes possible applications in investigation, measurement, etc. This report covers the design concepts of this flying robot, the structure design, basic control and operations verification.