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In this paper, we propose a flexible shoe system for biped robots to optimize energy consumption of the lateral plane motion. This shoe system is made to deform decline outside in the lateral plane and it can absorb the kinetic energy of the robot in the lateral plane. Furthermore, this hardware (shoes) and software (controller) can be easily applicable to the ordinary walking robot system. The effectiveness and characteristics of this system are confirmed by computer simulations and experimental results. It is confirmed that the stiffness of the shoe is a very important parameter for energy consumption by using computer simulations and experimental results.

In this paper, we describe the system design of the robots developed by our Team CIT Brains for the RoboCup soccer humanoid KidSize league. We have been participating in the Humanoid League for eight years. Two years ago, we redesigned the system to put a large weight on maintainability and usability. In RoboCup 2014, we won the first prizes of 4on4 soccer and technical challenge. Consequently, we were awarded the Louis Vuitton Humanoid Cup. The system we developed has high mobility, well-designed control system, position estimation by a monocular camera, user-friendly interface and a simulator. The robot can walk speedily and robustly. It also has a feedback system with a gyro sensor to prevent falls. It detects positions of landmarks by color-based image processing. A particle filter is employed to localize the robot in the soccer field fusing the motion model and landmark observation.

In this paper, we describe technologies of the robot Accelite that is the winner of the RoboCup2015 Humanoid KidSize League. In 2015, the rules of the humanoid league were changed dramatically. The ball was changed from a monochromatic orange ball to a real soccer ball. Furthermore, the goal color was also changed from yellow to white. Therefore, the soccer robots in the humanoid league were not able to detect the ball based on just colors. We developed some detection methods and verified their effectiveness. Consequently, our robots detected the ball robustly and we succeeded in the technical challenge "Goal-Kick from Moving Ball". In RoboCup 2015, the field of play was also changed from a punch carpet to an artificial grass. Because the pile length of the artificial grass in RoboCup2015 was long, our robots were not able to walk robustly when we started to use the field. We also explain how we solved the problem. We also discuss how we succeeded in the technical challenges.

In this paper, we propose flexible shoe system to apply passive walking manner to ordinary humanoid biped. In this system, 2DOF (FF & FB) control scheme is used and realize walking with less ankle torque. Besides, this system is consisted as reference modification of position control system, so it can be applicable to most of walking robot even if its joint servo is black box. The effectiveness and characteristics of this system is confirmed by computer simulations and experimental result. The softness of shoe is very important parameter for energy consumption and walking stability. From the discussions of the system, it is said that sagittal plane assistance shoes reduce the energy loss due to the ankle joint friction. Finally, we confirmed the reduction of energy consumption on walking experiment, so we call this system as “energy saving shoes.”

A leg extender exoskeleton is very useful when doing work involving tall shelves, looking around for security, etc. Therefore, we developed an exoskeleton with an active ankle joint. Its weight is approximately 12 kg and it extends the leg length by 40 cm. The operational feeling of exoskeleton may depend on the link length configuration. In this pager, the Linearity Index is introduced to realize natural feel of exoskeleton.

This paper describes considerations on a Voltage Source Inverter based Reactive Power Compensator, especially load balancing control by symmetrical coordinates frame. Analytical expressions are derived to design the current controllers. With the designed controllers, fast response to the step changes in the reference current values can be obtained. This results in the improvement of the overall system performance. The improved current tracking capabilities of the inner controllers and better performance characteristics of dc voltage and reactive power loops are demonstrated for steady state and transient conditions. Besides this, the required additional loops for load balancing property of the VSI based SVC are investigated by using the positive - negative sequence decomposition calculated in α - β reference frame which gives a faster response than the separation in d-q frame. Simulation results have shown that with the use of simple additional loops, VSI type SVC can also achieve load balancing besides VAR compensation and dc voltage regulation.

In this paper, we present an experimental result of 3-D real-time speed-variable biped walking using our second prototype Ostrich-II. Ostrich-II has 10 degrees of freedom; 6 for sagittal plane and 4 for lateral plane. The synchronization of motions in both planes is very important to realize stable walking. We propose Virtual Inverted Pendulum(VIP) method as the solution. We introduce following two techniques; (a) synchronization of the motions in both planes, (b) realization of synchronized acceleration/deceleration. We made an actual biped machine and its control system. We confirmed the effectiveness of VIP method by laboratory experiment. Ostrich-II realizes variable real-time biped walking, such as steady walking (0.5s/step, 0.1m/s), acceleration( from 0.lm/s to 0.2m/s, etc.), and so on.

We propose a biped locomotion system that its gait is changeable in real-time. Our targets are; artificial leg, slave machine, remote-brain home-robot, etc. Our dream is to develop new transportation tool that rider can control its gait. We call this imagination as “Biped Bike.”In this paper, we discuss the way of real-time gait control of biped locomotion. We propose Virtual Inverted Pendulum (VIP) Method for controlling the walking speed. This method considers the continuity of biped walking especially on transient status such as acceleration and deceleration. The actual biped system is made and real-time gait control is realized using VIP method.

This paper describes the operationality improvement control for electric power assisted wheelchairs. “Electric power assisted wheelchair” which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of the straight and circular road driving must be further improved because the two wheels drive independently. This paper proposes the operationality improvement control by fuzzy algorithm to realize the stable and reliable driving on straight and circular roads. The suitable assisted torque of the right and left wheels is determined by fuzzy algorithm based on the posture angular velocity, the posture angle of the wheelchair, the human input torque proportion and the total human torque of the right and left wheels. Some experiments on the practical roads show the effectiveness of the proposed control system.

This paper describes a novel step climbing control scheme for electric power assisted wheelchairs. "Electric power assisted wheelchair" which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people. This research aims at realizing the safe and reliable step climbing motion control of power assisted wheelchairs because power assisted wheelchairs are in danger of overturning backward when raising the front wheels due to the excessive driving torque and of stopping in front of steps when the rear wheels try to climb over steps due to the insufficient driving torque. This paper proposes a novel step climbing control scheme for power assisted wheelchairs based on driving mode switching. The first driving mode, "front wheel raising mode", applies torque control system with the variable assistance ratio to prevent the dangerous overturning. The second driving mode, "rear wheel climbing mode", applies position control system based on the polynomial trajctory to surely climb over steps and stop at the suitable position. The mode switching control based on these two driving modes can generate the safe and reliable step climbing motions. Some experiments show the effectiveness of the proposed control system.

In this paper, we propose CPG (central pattern generator) based walking utilizing swing of arms. This method is aiming the effective use of upper-body of the humanoid. In sense of CPG applications, CPG based pattern generation technique for lower-body was proposed by other researchers. So, we apply CPG technique to swing of arms. It can be expected that the utilization of arm swing provides good performance to yaw moment stability, and recovery from stumbling. The effectiveness of this method is confirmed as improvement of accuracy of straight walking

We have extended the idea of passive walking from the viewpoint of energetic efficiency, to realize medical, nursing and home-use robots. In this paper, we propose flexible shoe system to apply passive walking manner to ordinary humanoid biped. This flexible shoe system works as an arc-shaped foot. Besides, a 2DOF(Feedforward & Feedback) control scheme is used in this system, that realizes walking with less ankle torque. Computer simulation study confirmed that this shoe system reduces about 80% of energy consumption of ankle joint in some cases. Using an actual small biped, we also confirmed that suitable stiffness shoes reduce about 8% of walking energy of the robot.

For realization of medical, nursing and home-use robots, energetic efficiency must be improved more and more. Therefore, the authors' group has extended the idea of passive walking from slope to flat floor, using a small power actuator. They call this walking system the pseudo passive walking robot (PPWR). Besides, they analyze the manner of passive walking system with variable leg length. They confirm that leg length control works as an ankle joint torque input. Based on this study, an experimental system PPWR-II, II-R, III can be developed and realizes stable passive walking on flat floor. They examined various parameters on this experiment. The weight balance of the robot, parameters on leg length control, energy consumption and so on. They found that careful tuning of these parameters provides good reduction of walking energy consumption. In addition to these basic studies of PPWR, they consider the expansion of flexible shoe system. This system provides two functions. One is torque assist function equivalent to arc-shape foot. The other is stabilization function on non walking phase. This flexible shoe system can be made with split shoe with spring elements. Equivalent conditions can be introduced using the above analysis of passive walking with arc-shape foot. Based on this condition, they made a split shoe system, and realized passive walking on flat floor similar to the above experiment.

Biped walking has been regarded as a promising locomotion applicable to medical, nursing and home-service robots. However, the influences of foot strike have not been widely discussed. In this paper, we present the experimental result about the collision between the tip of a 2-link system and the floor. We compare the result with computer simulation. These considerations are used to improve the walking stability and energy efficiency with our actual biped machine.

Minakata and Hori (1998) proposed a method for real-time variable speed biped walking. From experimental results using that method, we found that there is a suitable relationship between walking speed and step cycle time. Besides, this relationship (we call this the gait characteristic) is similar to that of human walking. We consider the reason for these characteristics. Walking stability at various speeds and cycles was simulated. We found that shorter step cycle is more stable in higher speed walking. Also we tried a walking experiment with human characteristics. Acceptable walking speed range becomes smaller than the case with a suitable parameter for our robot. In addition, a 2-link passive joint biped walking model is considered for energy saving walking. Touchdown impact force is simulated and examined by an experimental system. Various gait patterns are simulated and classified to 3 patterns. From computer simulation, pattern B is superior for reduction of touchdown impact.