The idea: use RL + graph search to learn to reach visually indicated goals, using offline data. Starting with data in an environment (which in our case was previously collected for another project, BADGR), train a distance function and policy for visually indicated goals.
2/n
Once we have a distance function, policy, and graph, we search the graph to find a path for new visually indicated goals (images), and then execute the policy for the nearest node. A few careful design decisions (in the paper) make this work much better than prior work.
3/n
This system can then be used in a few interesting ways: we can define "contactless delivery" targets just by having someone take a photo of their front door, and the robot then navigates to their front door to deliver their package.
4/n
Or you could command the robot to patrol an area by giving it visually indicated waypoints, simply by snapping photographs of each waypoint.
5/n
I think this method is promising for a few reasons:
- offline training using large prior datasets
- fully autonomous
- flexible, new goals specified just using images
In experiments, data was collected ~6 mo prior (for another project), so it's even robust to changing seasons :)
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My favorite part of @NeurIPSConf is the workshops, a chance to see new ideas and late-breaking work. Our lab will present a number of papers & talks at workshops:
thread below ->
meanwhile here is a teaser image :)
At robot learning workshop, @katie_kang_ will present the best-paper-winning (congrats!!) “Multi-Robot Deep Reinforcement Learning via Hierarchically Integrated Models”: how to share modules between multiple real robots; recording here: (16:45pm PT 12/11)
Tonight 12/10 9pm PT, Aviral Kumar will present Model Inversion Networks (MINs) at @NeurIPSConf. Offline model-based optimization (MBO) that uses data to optimize images, controllers and even protein sequences!
The problem setting: given samples (x,y) where x represents some input (e.g., protein sequence, image of a face, controller parameters) and y is some metric (e.g., how well x does at some task), find a new x* with the best y *without access to the true function*.
Classically, model-based optimization methods would learn some proxy function (acquisition function) fhat(x) = y, and then solve x* = argmax_x fhat(x), but this can result in OOD inputs to fhat(x) when x is very high dimensional.
Greg Kahn's deep RL algorithms allows robots to navigation Berkeley's sidewalks! All the robot gets is a camera view, and supervision signal for when a safety driver told it to stop.
The idea is simple: a person follows the robot in a "training" phase (could also watch remotely from the camera), and stops the robot when it does something undesirable -- much like a safety driver might stop an autonomous car.
The robot then tries to take those actions that are least likely to lead to disengagement. The result is a learned policy that can navigate hundreds of meters of Berkeley sidewalks entirely from raw images, without any SLAM, localization, etc., entirely using a learned neural net
Can we view RL as supervised learning, but where we also "optimize" the data? New blog post by Ben, Aviral, and Abhishek: bair.berkeley.edu/blog/2020/10/1…
The idea: modify (reweight, resample, etc.) the data so that supervised regression onto actions produces better policies. More below:
Standard supervised learning is reliable and simple, but of course if we have random or bad data, supervised learning of policies (i.e., imitation) won't produce good results. However, a number of recently proposed algorithms can allow this procedure to work.
What is needed is to iteratively "modify" the data to make it more optimal than the previous iteration. One way to do this is by conditioning the policy on something about the data, such as a goal or even a total reward value.
Interested in trying out offline RL? Justin Fu's blog post on designing a benchmark for offline RL, D4RL, is now up: bair.berkeley.edu/blog/2020/06/2…
D4RL is quickly becoming the most widely used benchmark for offline RL research! Check it out here: github.com/rail-berkeley/…
An important consideration in D4RL is that datasets for offline RL research should *not* just come from near-optimal policies obtained with other RL algorithms, because this is not representative of how we would use offline RL in the real world. D4RL has a few types of datasets..
"Stitching" data provides trajectories that do not actually accomplish the task, but the dataset contains trajectories that accomplish parts of a task. The offline RL method must stitch these together, attaining much higher reward than the best trial in the dataset.