Kunio Kojima

Development of life-sized high-power humanoid robot JAXON for real-world use

This paper presents the development of life-sized high-power humanoid robot JAXON. Humanoid robots for disaster relief assistance need the same degree of physical performance as humans. We have developed STARO as the high-power humanoid robot with a high degree of physical performance. However this is not enough for practical use of the humanoid robot in a disaster site. We consider the following as additional conditions to operate humanoid robots for disaster relief assistance outside of the lab in outdoor environments. 1) Robots have humanlike body proportion to work in infrastructure matched to human body structure. 2) Robots have energy sources such as batteries and act without tethers. 3) Robots walk with two legs or four limbs and continue to work without fatal damage in unexpected rollover. JAXON satisfied these conditions. We demonstrates the performance of JAXON through the experiment of getting out of a vehicle, stepping over walls, and operating on batteries. Further more, we assesses the performance of the strong armor and the shock absorbing structure through a backward over-turning accident.

Shuffle motion for humanoid robot by sole load distribution and foot force control

In situations where humanoid robots with constrained posture walk through a narrow space (e.g. manufacturing plants and kitchens), shuffling motions that are stepless and possess wide foot supporting area are effective. One of the difficulties of humanoids shuffle translations is the load distribution between both feet. If sole loads are not distributed appropriately, the humanoid robot cannot maintain target contact states of each foot, and it will result in slipping both feet or falling down. In this paper, we propose Slide Friction Control (S.F.C.): offline pattern generator and Slide Contact Stabilizer (S.C.S.): online controller. First, Slide Friction Control determines reference foot forces and COM trajectories by adjusting sole loads and considering kinematic friction. The appropriate load distribution of S.F.C. enables humanoid robots to maintain target foot contact states. Second, Slide Contact Stabilizer controls each foot by using damping control to realize reference foot forces determined by S.F.C. S.C.S. enables humanoid robots to slide foot smoothly by suppressing friction vibrations. We also take into consideration the dynamic balance of humanoid robots such as previous waking stabilizers. Finally, we demonstrate that the proposed system enables humanoid robot to slide their feet smoothly using a life-sized humanoid robot, HRP-2.

Development of humanoid robot system for disaster response through team NEDO-JSK's approach to DARPA Robotics Challenge Finals

This paper presents Team NEDO-JSKs approach to the development of novel humanoid platform for disaster response through participation to DARPA Robotics Challenge Finals. This development is a part of the project organized by New Energy and Industrial Technology Development Organization. Technology for this robot is based on the recent research of high-speed and high-torque motor driver with water-cooling system, RTM-ROS inter-operation for intelligent robotics, and generation of full-body fast dancing motion, due to the generic 10 years research of HRP-2 as a platform humanoid robot. Development target is the robot support in a variety of unsafe human tasks teleoperated by humans in case of a disaster response, equipped with body structure capability for use of human devices and tools in human environment, performance for dynamic full-body actions covering human-sized speed and power, and basic function for intelligent and integrated robot platform system for performing various tasks independently. we also describes NEDO-JSK teams approach to design methodology for robot hardware and architecture of software system and user interface for DRC Finals as a test case of disaster response.

Multi-layered real-time controllers for humanoid's manipulation and locomotion tasks with emergency stop

This paper describes a practical method to construct real-time controllers to achieve locomotion and manipulation tasks with a humanoid robot. We propose a method to insert emergency stop functionality to each layer to avoid robots falling down and joint overloads even if recognition and planning error exist. We explain implementation of multi-layered real-time controllers on HRP2 robot and application to several manipulation and locomotion tasks. Finally, we evaluate emergency stop functionality in several manipulation tasks.

Real-time skating motion control of humanoid robots for acceleration and balancing

In this paper, we propose a real-time control method for skating motion of humanoid robots. There are three problems for skating motion: (1) keeping dynamic balance, (2) adequately controlling foot force to suppress slipping at the foot, (3) controlling full-body motion in real-time. For solving these problems, we propose the Skating Motion Generator and the Skating Motion Stabilizer. In the Skating Motion Generator, we separate the slip suppression from motion generation for (3). The separation enables us to generate skating motions in real-time. In the Skating Motion Stabilizer, we adjust the sole pressure distribution of each foot to solve the contradiction between (1) and (2). We show the effectiveness of the proposed controller through the experiments, in which life-sized humanoid HRP-2 pushes the ground and skates on the skateboard. Applying the proposed controller, HRP-2 could successfully accelerate and skate on the skateboard at 0.5[m/s].

Rotational Sliding Motion Generation for Humanoid Robot by Force Distribution in Each Contact Face

Recent studies have explored humanoid robots in contact with the environment in various ways. However, many of them assumed static rather than sliding contacts. Studies on humanoid shuffle motion planning have realized sliding motions, such as turning, but relied on quasi-static balance control. In this letter, we propose a dynamic balance control method for sliding contact motions. The proposed method consists of the distributed force contact constraint (D.F.C.C.), which describes rotational sliding contact constraints, and the slide friction control (S.F.C.), which controls humanoid dynamic balance based on the model predictive control by using the D.F.C.C. The D.F.C.C. segments a contact face into a grid of contact points and optimize the vertical component of the contact forces. This enables us to calculate the sliding friction forces at each contact point. The S.F.C. is the model predictive control for distributing contact forces to each contact face considering sliding frictional dynamics. The D.F.C.C. is simple and easy to apply to the S.F.C. In our online stabilizer, we control not only a ZMP, but also contact forces for realizing the contact force distributions planned in the S.F.C. Finally, we show our methods validity through the experiment using life-sized humanoid robot JAXON.

Walking control in water considering reaction forces from water for humanoid robots with a waterproof suit

In this paper, we develop a waterproof suit for humanoid robots and propose an underwater walking control method. Although very few life-sized humanoid robots are completely waterproof, we can easily make these humanoid robots watertight by putting a waterproof suit on them. In water, humanoid robots are influenced by the two forces due to the water: buoyancy and drag force. We take buoyancy into account when generating a walking pattern because the force is large and easy to estimate before walking. However, drag force is small and difficult to precisely predict and therefore, we treat the force as an unknown disturbance. In our method, we modify footsteps based on the Capture Point in order to deal with large disturbances. We verify the effectiveness of the proposed methods through an experiment in which a life-sized humanoid robot walks on a floor, stairs and debris in water.

Online master-slave footstep control for dynamical human-robot synchronization with wearable sole sensor

In this study, the authors aim to let us control the whole body of humanoid robot dynamically as we want. For that, the authors focused on the direct control of the humanoid leg that is the most severe problem with humanoid tele-operation. The authors implemented online real-time human motion imitation system for humanoid with its dynamics influence considered. In that system, the authors assume both operator and robot as a linear inverted pendulum, and apply humans COM, ZMP, and both feet positions for robot control input. The system includes two 6-axis force sensor under the operators sole, and the sensors can precisely detect contact of humans sole. Finally the authors succeeded to control two robots that have different COM height configuration.

Achievement of dynamic tennis swing motion by offline motion planning and online trajectory modification based on optimization with a humanoid robot

In order for a humanoid robot to achieve higher physical performance, it is important to generate dynamic whole-body motion under the constraints of physical limitations and dynamic balance. In this paper, we propose the method for generating dynamic whole-body motion such as sports motion based on optimization techniques. Taking a tennis forehand swing as an example of dynamic motion, we aim to increase the swing speed. The proposed methods are composed of the following two methods: 1) the offline swing optimization and 2) the online swing modification. In the offline swing optimization, we use non-linear optimization techniques to maximize the swing speed and satisfy the constraints. We generate all joint trajectories by optimizing control points of uniform B-splines. In the online swing modification, we modify a part of the optimized trajectories online considering joint velocity limits, since the predicted ball trajectory might change before a robot hits the ball. These methods are validated through the following experiments. First, we carry out the experiment in which the actual robot JAXON executes the optimal swing motion. We confirm that the method of the offline swing optimization generates the feasible motion which reaches up to 14.6m/s. We also apply the online swing modification to the optimized motion in the simulation. Then we evaluate how accurately we have to predict the ball trajectory.

Dance-like humanoid motion generation through foot touch states classification.

This paper proposes a humanoid dance motion generation system that deals with a huge variety of leg motions. While previous research only tackled on a few kinds of leg motions, original human dance leg motions contain various foot touch states such as slide, turn, and heel contact, as well as complex motions such as kick and twist. According to the dance literature, we found that there are seven major foot touch states that make dance motion more “dance-like”. Thus we present a method to classify the seven kinds of foot touch state from human dance motion data, and describe the various dance leg motions by using combinations of the foot touch states and key-frames. Based on these methods, we designed the humanoid dance motion generation system that enables humanoid robots not only to satisfy the geometric condition but also to imitate various human dance leg motions. Finally we show an experiment using a life-sized humanoid, HRP-2.