How to implement Rodney Brooks' subsumption model on ROS?

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I think the key idea of subsumption model is that the upper layer can either contain or suppress partial function units of lower layer. But the multiplexer is just a priority-based selector for velocity output. What's more，the multiplexer is just one single process.

However, all the inhibitors and suppressors in subsumption model is decentralized causing that we can insert them in any place of any layers.

the inhibitors are also very important, we can inhibit some behavior of lower layer immediately, and then do some sensing or calculating things, output the result instead to the lower layer. but there is not inhibitor in the cmd velocity multiplexer.

But the multiplexer is just a priority-based selector for velocity output.

That is cmd_vel_mux: topic_tools/mux can multiplex whatever you want.

What's more，the multiplexer is just one single process.

Couldn't you start multiple of them? I can imagine N mux nodes, with coordination nodes calling the mux/selected service at appropriate times would come close to what you describe.

but there is not inhibitor in the cmd velocity multiplexer.

How about switching to a 'zero input' in a cmd_vel_mux with (at least) two inputs: the normal one, and a topic that publishes a Twist with all zeros?

1. I don't think that "zero input" in a cmd_vel_mux is a good idea. I can not call it a inhibitor. If an output of a moudle in subsumption model is inhibited, the module send nothing at all. But the "zero" Twist msg is also a msg, it may call callback and activate some events of the lower layer.

1. And another key word is "partial". The upper layer can either contain or suppress "partial" function units of lower layer. However, cmd_vel_mux just make the upper layer contain or suppress the function of the "whole" lower layer. Would I know your idea? Thank you.