Cassie, bipedal robot, Dynamic Robotics Laboratory, Corvallis, Oregon, USA

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Bipedal Robot in Wildfire Awareness Report, Action News Now, Chico-Redding, California

Published on May 24, 2018

Video posted with permission:
Spencer Joseph, Reporter
Lorraine Dechter, Assignment Desk/Producer
Action News Now, Chico-Redding, CA

Cassie Blue is walking with control laws developed at Michigan in this publication: Da, X., Harib, O., Hartley, R., Griffin, B., & Grizzle, J. W. (2016). From 2D design of underactuated bipedal gaits to 3D implementation: Walking with speed tracking. IEEE Access, 4, 3469-3478.

Cassie was built by Agility Robotics. The robot's purchase was enabled by funding from NSF Inspire Grant ECCS-1343720 and Toyota Research Institute (TRI). The work on the control law was funded by NSF Grant NRI-1525006.

 

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Trolling Agility Robotics (or, We Love Your Bipedal Robot!)

Published on May 24, 2018

We have been working toward a principled approach to stair climbing when we saw Agility Robotics tweet on 25 May 2018 involving their Cassie walking on platforms. We could not resist posting what we have so far as well. Keep building those awesome robots!

Cassie Blue is walking with control laws developed at Michigan in this publication: Da, X., Harib, O., Hartley, R., Griffin, B., & Grizzle, J. W. (2016). From 2D design of underactuated bipedal gaits to 3D implementation: Walking with speed tracking. IEEE Access, 4, 3469-3478.

Cassie was built by Agility Robotics. The robot's purchase was enabled by funding from NSF Inspire Grant ECCS-1343720 and Toyota Research Institute (TRI). The work on the control law was funded by NSF Grant NRI-1525006.

 

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Bipedal Robot Cassie Blue's Clutzy Operators and a Segway: Bloopers

Published on May 25, 2018

Operator Error #1: Gantry hit the sidewalk and stopped, pulling Cassie Blue off the Segway.

Operator Error #2: Bruce thought we could go through the wall in some quantum mechanics trick!

Controller Error #3: Bad interactions between the Segway's control loop and Cassie Blue's controller. That is called instability!

Controller Error #4: See above!

Operator Error #5: Yukai commanded too big of a lean!

Segway Error #6: The Segway hit its internal speed limit and leaned backward to slow down without asking permission first from Cassie Blue, the rider. That was a really bad idea!

Cassie Blue is operating with control laws developed at Michigan in this publication: Da, X., Harib, O., Hartley, R., Griffin, B., & Grizzle, J. W. (2016). From 2D design of underactuated bipedal gaits to 3D implementation: Walking with speed tracking. IEEE Access, 4, 3469-3478.

Cassie was built by Agility Robotics. The robot's purchase was enabled by funding from NSF Inspire Grant ECCS-1343720 and Toyota Research Institute (TRI). The work on the control law was funded by NSF Grant NRI-1525006.

 

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Cassie vs scattered boards

Published on Jun 15, 2018

Cassie is an efficient, compliant, dynamic bipedal robot. Here in the Dynamic Robotics Lab directed by Dr. Jonathan Hurst we are researching control strategies that exploit the robot's natural dynamics. The controller here is demonstrating robust blind walking over unperceived disturbances.

Funded by
DARPA Award WN911NF-16-1-0002
National Science Foundation Graduate Research Fellowship Grant No. 1314109-DGE

Thanks to Agility Robotics for designing and producing Cassie.

 

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Feedback control of a Cassie bipedal robot: walking, standing, and riding a Segway

Published on Sep 20, 2018

 

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Bipedal Robot Cassie Blue and Maize vs the Polar Vortex!

Published on Jan 30, 2019

30 January 2019: We wanted to see how long Cassie could operate during the "polar vortex" that has shutdown the campus! Well, she did one hour and two minutes of continuous operation at -22 C (-8 F).

 

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Cassie: dynamic planning on stairs

Published on Feb 20, 2019

This video shows the progression of increasingly complex gait strategies from ATRIAS through recent results with Cassie. Specifically, Cassie's controller now includes planned footstep placements in addition to dynamic balancing, allowing access to substantially more complicated terrains.

 

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Cassie: dynamic walking with compliance

Published on Apr 23, 2019

Dynamic walking with Cassie, from simulation to outdoor experiments, utilizing the full dynamics of the robot to generate the walking gait. This includes leverage the compliance, i.e., springs, to achieve the desired walking gaits.

 

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Iterative gait design for Cassie

Published on Apr 26, 2019

Results of using DeepRL on a Cassie robot. Policies are trained in simulation and directly applied on hardware.

 

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Cassie vs Spin: a true story

Published on Jul 4, 2019

Cassie Blue gets her independence on July 4th! In this video, Cassie Blue is navigating autonomously. Right now, her world is very small, the Wavefield at the University of Michigan, where she is told to turn left at any intersection. You're right, that is not a lot of independence, but it's a first step away from a human and an RC controller!

Using a RealSense RGBD Camera, Cassie Blue is building a 3D semantic map in real time that identifies sidewalks, grass, poles, bicycles, and buildings. From the semantic map, occupancy and cost maps are built with the sidewalk identified as walk-able area and everything else considered as an obstacle. A planner then sets a goal to stay approximately 50 cm to the left of the sidewalk's edge and plans path around obstacles and corners. The path is translated into waypoints that are achieved via Cassie Blue's gait controller.

While there is a lot left to do, we knew that Cassie Blue would enjoy celebrating Independence Day with you!

 

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Published on Jul 11, 2019

Cassie (30 Kg) is walking at a comfortable speed for human while carrying her (9 Kg) perception system. The original controller is used, with the definition of the virtual leg modified to be the line segment connecting overall Center of Mass to her toe. This moves the "control point" up about 10 cm.

 

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Learning spring mass locomotion on Cassie

Apr 2, 2020

This is the video that accompanies our submission to the 2020 RSS conference which is currently under review. Once the review process is complete, we will post our full text preprint on an open access site and add a link here. The full title is:

Learning Spring Mass Locomotion: Guiding Policies with a Reduced Order Model
Kevin Green, Yesh Godse, Jeremy Dao, Ross L. Hatton, Alan Fern and Jonathan Hurst

 

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Cassie Blue doing her thing on the U. of Michigan North Campus lawn

Jun 24, 2020

 

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Cassie vs the hill

Jun 25, 2020

The controller is designed for flat ground and treats the 22 degree slope as a disturbance. As you can "see'', Cassie is not equipped with a vision system in this video. This is called "blind walking", though, to be completely fair, the operator does have vision and it's hard to know if he is making subtle corrections over the RC controller. He says not....

 

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Cassie Blue goes a ridge too far

Jul 2, 2020

As our control skills increase, we are more and more impressed by what a Cassie bipedal robot can do. Those who have been following our channel, know that we always shows the limitations of our work. So while there is still much to do, you gotta like the direction things are going. Later this year, you will see this controller integrated with our real-time planner and perception system. Autonomy with agility! Watch out for us!

Valley 1: 0:00
Valley 2: 1:11
Crossing Ridges 1: 2:03
Crossing Ridges 2: 2:43

 

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Bipedal robot Cassie Blues reaches a walking speed of 2.1m/s

Jul 21, 2020

We are using distance traveled divided by time to estimate the velocity. The distance traveled is marked at time 0:39 of the video; see also here (https://youtu.be/lu_jcL84wNE?t=39). The plot shown at time 0.37 (https://youtu.be/lu_jcL84wNE) is an independent estimate from a Kalman Filter. When we get a chance, we'll try the same experiment on a running track without the gantry.

Can Cassie walk faster? Probably not, without running!

 

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Cassie robot learns to hop, run and skip

Oct 25, 2020

These are some preliminary results of our lab's new work on using reinforcement learning to train neural networks to imitate common bipedal gait behaviors, without using any motion capture data or reference trajectories. Our method is described in an upcoming submission to ICRA 2021. Work by Jonah Siekmann and Yesh Godse.

 

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Article "Forget Boston Dynamics. This robot taught itself to walk"
Slick, viral videos from Boston Dynamics are impressive but teaching a robot to walk by itself is a lot harder.

by Will Douglas
April 8, 2021

 

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Robot learns to climb stairs blind

May 19, 2021

We successfully used reinforcement learning to train a recurrent neural network to control our bipedal robot Cassie to climb stairs without any perception sensors such as LIDAR or cameras.

This video accompanies our submission to the 2021 Robotics: Science and System conference. A preprint of the full paper can be found here https://arxiv.org/abs/2105.08328.

"Blind Bipedal Stair Traversal via Sim-to-Real Reinforcement Learning" Jonah Siekmann, Kevin Green, John Warila, Alan Fern, Jonathan Hurst

 

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Reliability tests of a learned stair climbing controller

May 19, 2021

To show how reliable our learned controller is, we wanted to publish an uninterrupted video of ten stair ascents and ten stair descents. The controller being tested is described in our 2021 Robotics: Science and Systems paper "Blind Bipedal Stair Traversal via Sim-to-Real Reinforcement Learning" Preprint: https://arxiv.org/abs/2105.08328