Lesson 15 of 21 in this unit
Predict several actions at once.
Compare predicted action chunks with fresh-feedback execution.
By the end: Compare predicted action chunks with fresh-feedback execution.
Prerequisites and path options
Why learn this? Compare the work saved by action chunks with the delayed feedback and errors they can introduce.
Start with something concrete.
Planning three pushes at once can reduce decision calls. A bump after the first push can also make the remaining two commands stale.
Try the interactive modelDoes predicting three actions require executing all three?
Change one thing. Watch what follows.
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Understand what changed.
A shorter explanation, with the original worked examples available below. Both explain the same experiment and its limits.
The question
Planning three pushes at once can reduce decision calls. A bump after the first push can also make the remaining two commands stale.
Try it and inspect what changed
Compare horizons one and three using the same trained weights and displacement.
Inspect the selected receipt immediately after the ninth interval. Compare observedAt between single-step and chunk modes. Count observations and learned-policy calls, then compare full-task success and final error. Keep drag, delay and random offsets matched.
The calculation in words
Six network outputs encode commands at offsets zero, one and two. Targets are consecutive teacher commands, with the last available command repeated at the episode boundary. A horizon of three executes all three outputs; a horizon of one executes only the first and requests another observation. Each command lasts 0.1 seconds.
Keep the conclusion within the evidence
A three-command block spans 0.3 seconds. If a disturbance occurs just after its first command, two later commands can be issued without seeing the changed position. Fewer calls therefore trades feedback frequency against execution work. The model can be frozen throughout; observing again is not retraining.
The interface reports simulated seconds, not real latency or energy. Chunk predictions are learned, but the scheduler choosing how many to execute is programmed. These public comparisons do not establish real-robot timing safety.
You can explore every lesson directly. Completing this page, submitting a project report and demonstrating understanding on a separate case are different records. Optional code is available in the robot-learning studio; it does not increase guided lesson completion requirements.
Open the full worked examples, calculations and limitations
This is the same reference used in Technical mode. Expand it whenever you need the exact numbers, assumptions or further explanation.
Start with the task
Planning three pushes at once can reduce decision calls. A bump after the first push can also make the remaining two commands stale.
Mechanism and units
Six network outputs encode commands at offsets zero, one and two. Targets are consecutive teacher commands, with the last available command repeated at the episode boundary. A horizon of three executes all three outputs; a horizon of one executes only the first and requests another observation. Each command lasts 0.1 seconds.
A three-command block spans 0.3 seconds. If a disturbance occurs just after its first command, two later commands can be issued without seeing the changed position. Fewer calls therefore trades feedback frequency against execution work. The model can be frozen throughout; observing again is not retraining.
Work through the evidence
Inspect the selected receipt immediately after the ninth interval. Compare observedAt between single-step and chunk modes. Count observations and learned-policy calls, then compare full-task success and final error. Keep drag, delay and random offsets matched.
Compare horizons one and three using the same trained weights and displacement.
What this experiment can establish
The interface reports simulated seconds, not real latency or energy. Chunk predictions are learned, but the scheduler choosing how many to execute is programmed. These public comparisons do not establish real-robot timing safety.
Keep collection, fitting, frozen execution and interpretation as separate records. Save the configuration and complete result, including failures, in the robot-learning project. Report submission checks required evidence and text presence; reasoning and implementation quality need independent review.
A three-command chunk lasts 0.1 s per command. A bump follows command one. How many stale commands can remain?
Take this idea with you.
The interface reports simulated seconds, not real latency or energy. Chunk predictions are learned, but the scheduler choosing how many to execute is programmed. These public comparisons do not establish real-robot timing safety.
Explore related topics and the topic map
How this topic connects
Explore this topic on the interactive mapUse these connections to review a foundation or choose where to go next. You can open any topic without completing the others.
What it builds on
- Geometry and control
Prevent coordinate-frame mistakes when combining robot positions, sensor readings and targets.
Compare predicted action chunks with fresh-feedback execution.
What it enables
- Robot-learning project Apply in a project
Combine demonstration provenance, policy comparisons and complete-task evidence in the robot-learning project; keep embodiment limits and review status explicit.