ENGLISH/JAPANESE
wabian img Biped humanoid robot group

WABIAN-2R (2006-)
(WAseda BIpedal humANoid No.2 Refined)
 * Purpose
 * Achievements
    * WABIAN-2R
    * Application as a human
       motion simulator
    * Application in the real
       environment
 * Collaborative research
 * Future work
 * Acknowledgements
 * WABIAN-2 (2005)
 * WABIAN-2/LL
    (2003-2004)
 * Development of robots in
    Kato/Takanishi Laboratory
 * Papers

■ RoboSoM -A Robotic Sense of Movement-
"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!
RoboSoM


 * Purpose

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

Humanoid_Robot

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.


2. Biped humanoid robot as a human motion simulator

walk-assist_machine walk-assist_machine

Application as a human motion simulator
  In the near future Japan is becoming an aging society. A quite high number of the olders are suffering from disabilities and problems in their lower limbs. This increases the demand for the development of welfare equipments. However, conventional evaluation methods for the equipments depend on human body measurements, and there are problems of the reproducibility, measuring accuracy, and human safety during the experiments,in particular.
  Therefore, our group has suggested applying a biped humanoid robot as a human motion simulator. That means a robot which can perform equal exercises with human beings tests welfare equipments under development in place of a human, and provides quantitative data. We expect this new evaluation method would be safe, quantitative and versatile.

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 *  Achievements
 *  WABIAN-2R

* Specification


Humanoid_Robot Humanoid_Robot
Height mm 1500
Weight kg 64 (with batteries)
Degrees Of Freedom (DOF)
Leg: 6×2
Foot: 1×2 (passive)
Waist: 2
Trunk: 2
Arm: 7×2
Hand: 3×2
Neck: 3
Total: 41
Sensors 6-axis force/torque sensor
Photo sensor
Magnetic encoder
Gyro sensor
Actuators DC servo motor
Reduction mechanism Harmonic drive gear
Timing-belt/pulley
Batteries Li-ion battery
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)

  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)


pelvis_DOF
2-DOF model for the waist mechanism
  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
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
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]
Stretch Walking 2
(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)


  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.
WABIAN-2 with a walk-assist machine

Walking experiments with a walk-assist machine  (2005)
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)


  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)
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]
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
Detail 1
(mpg/8[s]/1.3[MB])

Comparison of the foot motions between the robot and human
Detail 2
(mpg/12[s]/2.1[MB])

Detail of the foot motion while walking



* Emulation of a disabled person's gait  (2007)


  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.

Emulation of a disabled person's gait


Emulation of a disabled person's gait  (2007)
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)




        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.

Walking with heel contact and toe-off motion of WABIAN-2R equiped with feet containing human-like arch structure.
Overal view
(mpg/12[s]/1.9[MB])

Walking cycle: 1.0[s/step]
Step length: 450[mm/step]
Foot detailed view
(mpg/12[s]/1.9[MB])

Walking with changing arch




* Quick turn by using slipping motion with both feet  (2010)




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
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]



*Leg mechanism mimicking walking on frontal and horizontal plane  (2012)




Leg mechanism mimicking walking on frontal and horizontal plane
  Few researches were conducted on the movement of the center of mass (CoM) for the frontal plane in biped humanoid robots. Hence, the goal of this study is to mimick the CoM movement in human walking on the frontal plane.
  In humans, the amplitude of the movement of the CoM to the right and left on the frontal plane during walking is 30 mm. However, for WABIAN-2R it is 50 mm, i.e. almost twice as big as for humans.
  One of the possible causes is that on the horizontal plane, WABIAN-2R is not able to mimick the human walking, because the step width of humans is 90 mm, while for WABIAN-2R it is 180 mm.
  That is why we have developed a new leg mechanism with the size of a human leg and with a foot angle and step width closer to those of a human. Walking with a step width of 90 mm and a foot angle 12 deg is achived, mimicking human walking on the frontal plane.
  Moreover, the movement amplitude of COM to the right and left on the frontal plane during walking of WABIAN-2R became 34 mm, being comparable to the humans' one.


standstill(step width:90[mm],foot angle:12[deg])
standstill
(.m1v/ 8[s] 10.5[MB])

Walking cycle:0.6[s/step]

Step width:90[mm] Foot angle:12[deg]

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 *  Application in the real environment

* Experiments in public roads in Fukuoka city  (2006-2007)


  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



* Foot mechanism adapting to the ground  (2008-2010)


  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.
Foot able to sens the surface shape Foot adaptation

Walking on rough terrain in laboratory conditions (2009)    ○Walking on inclined surface (2009)
Verification of foot adaptation to uneven surface
(mpg/14[s]/2.0[MB])

Height of obstacles: 5-20[mm]
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)
Rough and inclined surface
(mpg/13[s]/1.8[MB])

Undulation height: 0-15[mm]
Inclination: 8.0[deg]

  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.
    3-point Contact Foot Mechanism

Prevention of the foot slippinge (2010)
Previous method
(mpg/16[s]/2.0[MB])

Height of obstacles: 20[mm]
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)
Verification of foot adaptation to uneven surface
(mpg/12[s]/1.5[MB])

Height of obstacles: 5-20[mm]
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]



* On-line generation of Furrier Transform based gait patterns   (2009)




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
Walking with waist height modification
(mpg/24[s]/3.9[MB])

Walking cycle: 1.0[s/step]
Step length: 200[mm/step]
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)




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.



* Walking on soft ground  (2012)


  Until now, there have been many researches aimed towards the stable walking of bipedal walking robots on real environment surfaces, but most of the successful researches were performed on rough terrains, hard enough not to deform.
  However, in the real world there are not only hard grounds, but also many kinds of soft grounds such as sandy or snowy surfaces.
  In this study, the goal was to achieve a stable walking on soft ground which by nature tend to change their shape. More specifically, we aimed to design a control system able to deal with soft ground, based on a prediction of the deformation of the surface given the force applied to it, obtained by modeling the soft ground.
  By the development of a control to correct the posture of the foot in response to the deformation of the ground, we succeeded in the stable walking on a very soft urethane sponge (density: 22 ± 2 [kg / m 3 ]).
    The summary of the control on soft ground

standstill on soft ground
(.mpg/11[s] 1.5[MB])

Walking cycle:0.9[s/step]
Walk on soft ground
(.mpg/ 11[s] 13.8[MB])

Walking cycle:0.9[s/step]
Step length:200[mm/step]



* Simulation Based Study of Bipedal Robot on Moon Gravity  (2010)




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

  "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/

SHINPO


  "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

KIYOMORI

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 * Future work
Future Works Future Works   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.
Future Work
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 * Acknowledgements
  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.
HRI Humanoid Robotics Institute, Waseda University
WABOT HOUSE WABOT-HOUSE Laboratory, Waseda University
TOYOTA Motor Corporation
The New Energy and Industrial Technology Development Organization  (NEDO)
The Robotics Industry Development Council  (RIDC)
SolidWorks Japan K.K.
QNX SOFTWARE SYSTEMS
DYDEN Corporation
KITO Corporation
tmsuk Co., Ltd.
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