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Biped humanoid robot group WABIAN-2R (2006-) (WAseda BIpedal humANoid No.2 Refined) |
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| "RoboSoM -A Robotic Sense of Movement-", a joint research project with Italy, France and Portugal, was accepted to the European Seventh Framework Programme (FP7) with the highest score! | ||
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| * Purpose |
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We have two purposes to develop a biped humanoid robot. The first one is to develop a robot that would be a human's partner, while the second one is to develop a human motion simulator. 1. Biped humanoid robot as a partner |
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 Cooperation with humans in various fields |
The robot industry thus far focused on developments of industrial robots, for highly specified and constrained applications.
The social demands and trends, however, push robotics into new areas, like medical treatment, life rescue, entertainment etc.
It is just a matter of time, when human beings will find robotic assistance necessary in their daily life. In order to accomplish these task, robots will have to be able to move in indoor and outdoor conditions. Biped humanoid robots are best suited for this application. |
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2. Biped humanoid robot as a human motion simulator
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| * Achievements |
| * WABIAN-2R |
* Specification |
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| Drawing | DOF configuration | |||||||||||||||||||||||||||||||||||||||
 Front |
 Right |
WABIAN-2R has been designed with 1.5m in height, and 64kg in weight. In order to mimic human movements, the robot has 41 DOFs and the movable range of the joints designed in reference to human's one. | |
| WABIAN-2R (2009) | |||
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The computer mounted on the trunk controls the motion of WABIAN-2R. It consists of a PCI CPU board and PCI I/O boards.
As the I/O boards, HRP interface boards (16ch D/As, 16ch counters, 16ch PIOs), and 6-axis force/torque sensor receiver board are mounted. The operating system is QNX Neutrino ver. 6.3. The drive system consists of a DC servo motor with an incremental encoder attached to the motor shaft, and a photo sensor to detect the basing angle. Also, each ankle has a 6-axis force/torque sensor, which is used for measuring Ground Reaction Force (GRF) and Zero Moment Point (ZMP). |
| Control system |
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| * Application as a human motion simulator |
* 2-DOF waist mechanism (2003) |
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Because of the mechanical constraint, most of the biped robots perform a bent-knee gait (walk with the knees bent during walking). On the other hand, researches on human gait's analysis show that the pelvis motion plays a significant role in human's gait. Taking into account the results of these researches, our team developed a 2-DOF (roll, yaw) waist. By using the redundant mechanism, the robot is able to perform a stretch-knee gait as well as human being does. | |
| Knee-bent walking |
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Conventional walking (mpg/13[s]/2.3[MB]) Walking with constant waist height Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
| Knee-stretch walking with waist movement |
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Stretch walking 1 (mpg/13[s]/2.3[MB]) Walking with the knees stretched Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
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Stretch walking 2 (mpg/12[s]/2.0[MB]) Walking with the knees stretched on tiled floor Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
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Stretch Walking 3 (mpg/12[s]/2.1[MB]) Walking with the knees stretched outdoor Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
* Walking experiments with a walk-assist machine (2005) |
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As one of the applications as the human motion simulator, we carried out walking experiments with a walk-assist machine.
Generally, an armrest of a walk-assist machine is set to equal height of a user's elbow.
And it is known that the severer his/her disability is, the lower we should set the armrest. Measuring the current value of the motors at the knee joints and the forces & torques which are applied to the arms and legs, we are able to calculate the energy consumption at knee joints and the load to arms. Then we found the fact with quantitative data that the lower we set the height of the armrest, the less the load of knees is. This is a good example that human motion simulator can evaluate empirical facts quantitatively. From the results of these experiments, we confirmed that we can evaluate welfare equipments quantitatively with a human motion simulator. |
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| WABIAN-2 with a walk-assist machine | ||
| Walking experiments with a walk-assist machine (2005) |
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Simulations of walking assisted by a walk-assist machine (mpg/8[s]/1.5[MB]) Knee-stretched walking with a walk-assist machine |
* Foot with a passive toe joint (2006) |
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A human foot has a complex structure consisting of a lot of bones. Based on the result of gait analysis with motion capture system,
we have developed a new foot which has a passive toe joint. Some of the clinical reports on toes' function indicate that toes do not produce thrust during steady gait. Since, in the current stage of our research, we focus on in steady walking, we have decided to develop a foot with a passive toe joint. Its main advantages are lightness and no necessity of a complex control. |
| Foot with a passive toe joint | |
| Human-like walking (Knee-stretched walking with heel-contact and toe-off motion) |
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Knee-stretched, heel-contact and toe-off motion 1 (mpg/13[s]/2.2[MB]) Indoor Walking cycle: 1.0[s/step] Step length: 350[mm/step] |
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Knee-stretched, heel-contact and toe-off motion 2 (mpg/11[s]/1.9[MB]) Indoor Walking cycle: 1.0[s/step] Step length: 500[mm/step] |
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Knee-stretched, heel-contact and toe-off motion 3 (mpg/13[s]/2.2[MB]) Outdoors Walking cycle: 1.0[s/step] Step length: 350[mm/step] |
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Knee-stretched, heel-contact and toe-off motion 4 (mpg/11[s]/1.9[MB]) Outdoors Walking cycle: 1.0[s/step] Step length: 400[mm/step] |
| Detail of the heel-contact and toe-off motion |
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Detail 1 (mpg/8[s]/1.3[MB]) Comparison of the foot motions between the robot and human |
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Detail 2 (mpg/12[s]/2.1[MB]) Detail of the foot motion while walking |
* Emulation of a disabled person's gait (2007) |
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As an example of the robot's applications, we had emulation experiments of a disabled person's gait. We used the walking data of a disabled person, recorded with motion capture system. Optimazing a part of walking parameters with Genetic Algorithm (GA), the robot achieve a good balance between walking stably and reproducting the gait. As the result, we confirmed the effectiveness from the stick diagram in the sagittal plane and the comparison of each joint angle. |
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Emulation of a disabled person's gait |
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| Emulation of a disabled person's gait (2007) |
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The emulation of a disabled person's gait (mpg/15[s]/2.7[MB]) Emulation of a disabled person's gait |
* Foot mechanism capable of imitating human arch structure (2009) |
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 Foot with human-like arch structure |
What is distinct in human beings compared to animals is that our feet are equipped with
arch like structure. Researchers in human science field agree that the arch in human foot has
significant influence to the gait, however it has never been fully investigated.
The goal of this research is to implement the arch containing foot in the humanoid robot and further elaborate the influence of the foot arch to the gait of human being. The stiffness of the arch changes depending on the stage of the gate. It is thought, that the stiffness is very low in the flat foot phase, it rises with movement of the body forward and reaches its highest value at the toe-off phase. Experiments we performed after completing the development, proved that the arch structure absorbs the impact generated when sole fully contacts the ground. |
* Swing pattern modification control (2009) |
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 Outline of the swing pattern modification control. |
Until recently, we used in our robot a posture error compensation control to perform
the stable gait. Since the implementation of the human like foot, much narrower
than the foot used thus far, the control algorithms turned out to be not able
to generate the stable gait. To solve this problem we implemented new control strategy
which, unlike the previous one, introduces a positive posture error. When the robot starts
falling towards the inner side, the swing leg abducts before touching the ground and stabilizes
the posture. The cycle is repeated for the opposite leg, simultaneously realizing the pattern.
By implementing this control strategy, we succeeded in generating stable gate with heel contact and toe-off phases in humanoid robot equipped with feet containing human-like arch structure. |
| Walking with heel contact and toe-off motion of WABIAN-2R equiped with feet containing human-like arch structure. |
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Overal view
(mpg/12[s]/1.9[MB]) Walking cycle: 1.0[s/step] Step length: 450[mm/step] |
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Foot detailed view
(mpg/12[s]/1.9[MB]) Walking with changing arch |
* Quick turn by using slipping motion with both feet (2010) |
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 Turn by using slipping motion |
Humans can do motions with a slip such as a shuffle and a turn.
It is expected that the advantage of slipping motions are quick, less energy consumption
and more stable against disturbing force because both feet are on the ground during a moton.
We realized a turn by slipping motion by switching ground contact conditions like human's slipping turn. Furthermore, we implemented a stabilization control by using the rear foot to keep the posture while turning. Those control realized quick turn about 90[deg] in about 2[s] by using slipping motion. Moreover, it is revealed that a slipping turn decreased 65% of the energy consumption compared with that of a stepping turn. |
| Quick turn by using slipping motion with both feet |
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Quick turn by using slipping motion with both feet
(mpg/7[s]/0.7[MB]) Turning phase: 1.5[s] Switching phase: 0.25[s] x 2 Angle of turn: 90[deg] |
* Measurement of human's plantar transverse elasticity (2010) |
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 Measuring equipment of human's plantar transverse elasticity |
We are trying to develop a now human-like foot to mimic the total mechanical characteristics of the humanfs planta,
especially the plantar elastic elements (e.g. the skin).
The compressive elasticity can be refered to a relevant study.
However, relevant studies of the transverse elasticity are not found.
So, we developed the measuring equipment and measured the human's plantar transverse elasticity.
We developed the measuring equipment which is capable of fixing a foot and an ankle joint of a subject, applying a transverse force, and measuring the force and the displacement by plantar deformation. From 3 subjects' data, we confirmed that the modulus of transverse elasticity of the humanfs planta is 11.2[N/mm]. |
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| * Application in the real environment |
* Experiments in public roads in Fukuoka city (2006-2007) |
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For expansion of applied fields, we experimented in the environment where a human being lives.
In particular, in public roads in Fukuoka city that was the one of the special zones for robot development and test,
to confirm problems with the present walking ability, and to develop new control systems. This experiment was commissioned by the Robotics Industry Development Council (RIDC). |
| Experiments in public roads in Fukuoka city | |
* Power supply system (2007) |
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WABIAN-2R can use an external power supply and Li-ion batteries inbuilt in the body. On the other hand, we also use the external power supply when tuning-up the robot, and the inbuilt battery when performing experiments.
WABIAN-2R can switch smoothly between the external power supply and the batteries, to realize effective experiments as a human motion simulator. Furthermore, WABIAN-2R can charge the batteries when operating with the external power supply. |
| Effective power supply management | |
* Foot mechanism adapting to the ground (2008-2010) |
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Since outdoor roads are not only rough and inclined, but also undulated it is not possible
to perform the stable gait with use of flat feet. To cope with outdoor roads irregularities we improved
the foot mechanism created in 2008 and come up with solution allowing us to negotiate also undulated surfaces.
By implementing four moving pins on the corners of the foot, we change from the surface contact to the four points ground contact. Moreover, by sensing the displacement of each of the pins, we sens the shape of the ground and optimize the foot placement. With this solution, we were able to realize stable walk on the undulated surface with 20[mm] high unevenness. |
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| Foot able to sens the surface shape | Foot adaptation |
| Walking on rough terrain in laboratory conditions (2009) Walking on inclined surface (2009) |
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Verification of foot adaptation to uneven surface (mpg/14[s]/2.0[MB]) Height of obstacles: 5-20[mm] |
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Verification of foot adaptation to the inclined surface
(mpg/14[s]/2.0[MB]) Robot starts the gait from the flat surface and proceeds to the slope inclined: 7.0[deg] |
| Walking outdoor on rough surface (2009) |
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Rough and inclined surface (mpg/13[s]/1.8[MB]) Undulation height: 0-15[mm] Inclination: 8.0[deg] |
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We have developed a 4-point contact foot mechanism with the function capable of detecting
ground surface for biped robots to realize stable walking on even/uneven terrain. However, a biped
robot with the foot mechanism was often unstable while walking on uneven terrain due to the small stability margin,
foot slipping and sensor glitches. So, a 3-point contact foot mechanism that can deal with uneven terrain is developed in this study. Biped robots will be able to retain larger stability margin, and prevent the foot from slipping at a contact point by using the new foot mechanism. The effectiveness of the new mechanism is confirmed through walking experiments. |
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| 3-point Contact Foot Mechanism |
| Prevention of the foot slippinge (2010) |
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Previous method (mpg/16[s]/2.0[MB]) Height of obstacles: 20[mm] |
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New method
(mpg/15[s]/1.8[MB]) Height of obstacles: 20[mm] |
| Walking on rough terrain in laboratory conditions (2010) Walking on inclined surface (2010) |
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Verification of foot adaptation to uneven surface (mpg/12[s]/1.5[MB]) Height of obstacles: 5-20[mm] |
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Verification of foot adaptation to the inclined surface
(mpg/13[s]/1.8[MB]) Robot starts the gait from the flat surface and proceeds to the slope inclined: 7.0[deg] |
* Walking stabilization control (2008) |
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 Outline of the walking stabilization control |
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The gravity and inertia force must be balanced in a robot walking pattern (joint angle data on every moment). However, there are many errors that are not considered when the pattern is generated like unevenness, and inclination of the ground, an error between the real robot and the robot model (multi-mass system) and bend of the frame. So, a consideration of only gravity and inertia is not sufficient to achieve stable walking. To solve this problem, WABIAN-2R modifies the pattern based on the data of the GRF and attitude during walking. |
In order to do that, we use a vertual compliance control that makes the landing impact smaller. And also, Landing Pattern Modification ControliLPMCj changes the position and posture of the foot to adapt to the ground. Posture control corrects the error of robot's posture. WABIAN-2R can walk on a road with big slope or bump up to 5[deg] (roll and pitch) or 20[mm] (only pitch) with these control methods. In practice, we showed the high performance in experiments outdoor at Fukuoka city - stable walking on a slope in a park and on an uneven sidewalk. |
| Walking experiment outdoor |
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Tiled uneven ground (mpg/13[s]/2.2[MB]) Bump 5mm Slope 2deg Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
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Big slope (mpg/13[s]/2.2[MB]) Slope 5deg Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
| 20mm bump in lab |
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Without detecting ground (mpg/13[s]/2.2[MB]) Whole foot on 20mm bump Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
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With detecting ground (mpg/13[s]/2.2[MB]) Toe & heel on 20mm bump Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
* On-line generation of Furrier Transform based gait patterns (2009) |
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 Flow chart |
 Calculation of compensation ZMP trajectory based on necessary compensation moment |
| Until now, gait patterns for WABIAN-2R were generated off-line and realized on the platform with on-line short-period pattern modifications. The disadvantage of this method is that in some circumstances, it is not possible to maintain a long time stability without modifying the predefined gait pattern. | In order to solve this problem we implemented an on-line generation of gait patterns. With this technology the robot can maintain long time stability. Moreover, it enables us to modify the gait trajectory on-line (e.g. with use of joystick). |
| Walking with online pattern generation |
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Walking with waist height modification (mpg/24[s]/3.9[MB]) Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
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Walking controlled with joystick (mpg/84[s]/14[MB]) Walking cycle: 1.0[s/step] Step length: 200[mm/step] |
* Device for repetitive application of disturbing force (2009) |
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 Disturbance generator |
In the real environment, robots are often subject to an unpredictable source of disturbance, like collision with obstacles or human. Our group works on control system for humanoid robots that would be able to respond to external disturbances. During algorithms verification experiments performed thus far, the disturbing force was applied by human. It is almost impossible for human to apply the same disturbing force in exactly the same phase of the gait, which is necessary to evaluate the efficiency of the algorithm. To solve this problem we developed machine able to repetitively generate the same disturbing force in any chosen time of the robot's gait. |
* Coordinated adaptive motion on lower limb (2010) |
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 Adaptive walking depending on the ground condition |
WABIAN-2R is capable of 2 walking styles, one is knee-stretched walking like a human, the other is knee-bend walking.
Knee-stretched walking enables fast walking. In contrast, knee-bend walking enables stable walking on uneven terrain.
In the real environment, it is preferable that WABIAN-2R change the walking style depending on the ground condition.
We developed a new inverse kinematics methods to generate walking motions of its legs regardless of the walking style and an online walking parameter generation to bend its knees depending on the ground condition. By using the methods and the online pattern generation method above, an adaptive walking was realized. |
| Adaptive walking by using coordinated adaptive motion on lower limb |
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Adaptive walking depending on the ground conditions
(mpg/17[s]/1.8[MB]) Unevenness: 0 - 20[mm] Walking cycle: 1.0[sec/step] Step length: 0.2[m] Adapting to an uneven surface by bending the knees is confirmed |
* Fundamental Study toward the Realization of Biped Walking on Soft Ground (2010) |
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Many researches have been carried out to realize biped walking on uneven terrain,
but most researches have focused on hard ground. The final goal of this study is to develop an
stabilization control so that biped robots can walk on a soft ground such as sandy soil.
As the first step, we targeted homogeneous soft grounds and made a model of grounds
with springs and dampers. Based on the model, the amount of deformations of the ground is estimated,
and the foot orientation is modified. By implementing the developed control on a bipedal humanoid
robot, the robot realized a stepping motion on a soft ground. | |
| Terrain adaptive control |
| Walking experiment on soft ground |
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Verification of adaptation to soft ground (mpg/21[s]/2.8[MB]) Height of obstacles: 20[mm] |
* Simulation Based Study of Bipedal Robot on Moon Gravity (2010) |
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 Forward jumping motion approach on moon gravity |
Humanoid robots are expected to be applied for not only in the real environment, but also in the ultimate environment.
For example, to explore the surface of the moon.
The challenge of developing a bipedial robot to walking on the moon is really high due to the low gravity compared with that on earth.
The effect of the low gravity doesn't allow biped robots to walk fast.
So, it is better to switch to a running or jumping motion instead of walking.
We investigate the ability to perform a running or jumping motion on the moon. |
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| * Collaborative research |
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"SHINPO" was developed in a collaboration of tmsuk Co., Ltd. and Atsuo Takanishi Laboratory for a part of the robot exhibition at Niigata Science Museum, which Uchida Yoko Co., Ltd. had contracted for. The 2-DOF waist enables it a more human-like walking style. Referential web page; Uchida Yoko Co., Ltd. http://www.uchida.co.jp/global/ Niigata Science Museum http://www.lalanet.gr.jp/nsm/english/index.html tmsuk Co., Ltd. http://www.tmsuk.co.jp/tmsuklab/ |
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| SHINPO | ||
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"KIYOMORI" was developed in a collaboration of tmsuk Co., Ltd. and the Atsuo Takanishi Laboratory. The same as "SHINPO", the 2-DOF waist enables it a more human-like walking style. Referential web page; "KIYOMORI" special web page http://kiyomori.jp/main.html |
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| KIYOMORI |
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| * Future work |
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We are trying to make the robot's ability higher to move close to humans and to have experiments with welfare equipments. In the future, we will establish the method to evaluate medical and welfare devices. Finally, we would also like to realize the human motion simulator, which can apply it to not only rehabilitation but also various fields. |
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| Future Work | |||
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| * Acknowledgements |
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A part of this research was commissioned by a Grant-in-Aid for the WABOT-HOUSE Project by Gifu Prefecture,
"Project for the Practical Application of Next-Generation Robots" by The New Energy and Industrial Technology Development Organization (NEDO),
The Robotics Industry Development Council (RIDC) and supported by Grant-in-Aid for Scientific Research (No.18360126)
from the Ministry of Education, Culture, Sports, Science and Technology. And a part of this research was a collaborative research with TOYOTA Motor Corporation.
This project is executed under Humanoid Robotics Institute, Waseda University. Special thanks to SolidWorks Japan K.K for the 3D-CAD contribution, to QNX SOFTWERE SYSTEMS for the OS contribution, to DYDEN Corporation for the wire and harness contribution, to KITO Corporation for the robot supporting crane contribution and to every cooperative companies, local governments and public agencies. |
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