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Adaptive - Fast Dynamic Walking Robot “RUNBOT”

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RunBot is a biomechatronic design. It has achieved a relative walking speed of 3.5 leg-lengths per second, which is much faster than the current world record of biped walking robots, 1.5 leg-lengths per second, and is even comparable to the fastest relative speed of human walking. Unlike other biped robots using various model-based controllers, RunBot's mechanical structure is directly driven by motor-neurons of its neuronal controller, which is analogous to what happens in human and animals' walking. In summary, neural computation and physical computation work together to generate RunBot's fast and adaptive walking gaits.

 

Technical Data:

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It is 23 cm tall, foot to hip joint axis. Each leg consists of two degrees of freedom: hip and knee joints. Each hip joint is driven by a modified RC servo motor producing a torque up to 5.5 kg.cm while the motor of each knee joint produces a smaller torque (3 kg.cm) but has fast rotating speed with 21 rad/s. The built-in servo control circuits of the motors are disconnected while the built-in potentiometer is used to measure the joint angles. A mechanical stopper is implemented on each knee joint to prevent it from going into hyperextention similar to human kneecaps.

Runbot has no actuated ankle joints resulting in very light feet and being efficient for fast walking. Its feet were designed having a circular form 4.5 cm long similar to passive biped robots. Each foot is equipped with a switch sensor to detect ground contact. This mechanical design of Runbot has some special features, e.g. small curved feet and a properly positioned center of mass that allow the robot to perform natural dynamic walking during some stage of its gait cycles .

 

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In addition, the active upper body component is implemented on the top of its hip joints for balance in walking on different terrains, e.g. up and down slopes. The active body has the total weight of 50 g. The active component is controlled by an accelerometer sensor implemented beside one hip joint. In order to effectively perform adaptive walking on different terrains, one infrared-based vision sensor is also installed at the hip joints and it points down forwards to detect the slope. The sensor signal serves as predictive signal in the adaptive control level. Runbot is constrained sagitally by a boom of one meter length. It is attached to the boom via a freely-rotating joint in the x axis while the boom is attached to the central column with freely-rotating joints in the y and z axes. Thus, the motions of Runbot are only constrained on a circular path. This set-up has no influence on dynamics of Runbot in the sagittal plane.

 

The reflexive neuronal controller of RunBot:

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(For more details of RunBot and its controller, read the papers )

Runbot performance:

See how fast it is :

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Changing speed on the fly by tuning the neuron parameters
You can see RunBot's gaits are quite natural, like human's walking gaits.

video1

 

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In this video, RunBot started from a slow gait. A real-time reinforcement learning algorithm is used to tune the neuron parameters online while RunBot is walking. At the end of the video, RunBot attained its fastest walking speed.

video2

 

Comparison of the walking speed of various biped robots whose sizes, they are quite different from each other, we use the relative speed, speed divided by the leg-length. The figure below shows the relative speed of some typical planar biped robots, RunBot, and human.

 

Runbot_F4.jpg

Dynamic walking on different terrains:

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The dynamic walking capability of Runbot on different terrains, e.g. level floor, up and down slopes up between 0 and 7.5 degrees.

video3

Learning to walk up slope (adaptive walking):

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Runbot learns to walk up slope with ICO learning. As a result, it can learn to adapt its walking gait together with leaning the body.

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News of RunBot :

NewScience.jpgDiscovery.jpgBBC.jpg GoettingenTageblatt.jpg

 


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