REP 145 improvements regarding bias estimation and gravity compensation#1
REP 145 improvements regarding bias estimation and gravity compensation#1peci1 wants to merge 3 commits intoSteveMacenski:rep_145_stevefrom
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Added notes on bias removal and calibration.
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| - When the device is at rest, the vector will represent the specific force solely due to gravity. I.e. if the body `z` axis points upwards, its `z` axis should indicate +g. This data must be in m/s^2. | ||
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| - Specific force is the non-gravity-induced acceleration of a body (or acceleration "relative to" free fall). That is why the specific force of a body in rest is +g (the specific force must be the opposite of gravity to keep the body in rest). Specific force of a free falling body is zero. |
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This reads like a definition, but isn't a specification. The sentence above states that "the vector will represent the specific force solely due to gravity" which means I guess that in this spec, we have already stated they must contain gravity
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I've added this paragraph mostly as a quick explainer distilled from Wikipedia for readers who do not know much about specific forces. So it is not meant as a specification. You are right that there is overlap with the previous paragraph.
What about this condensation of the 3 paragraphs into 2?
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The accelerometers report linear acceleration data expressed in the sensor frame of the device. This data is output from the driver as a 3D vector, representing the specific force acting on the sensor. This data must be in m/s^2.
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[Definition] Specific force is the non-gravity-induced acceleration of a body (or acceleration "relative to" free fall). That is why the specific force of a body in rest is +g (the specific force must be the opposite of gravity to keep the body in rest). Specific force of a free falling body is zero.
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Apologies, this is on a hiatus for me given the recent changes in employment. Need to baton down the hatches a bit and revisit things like this once I know what's going on
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I understand that, Steve. Would you be willing to merge this PR as is to ros-infrastructure#372, so that the discussion is not so fragmented? Alternatively, I could open a new PR for the REP and transfer all the activity there and drag the cart for a while instead of you ;) What do you prefer?
I was looking for a way to transfer an existing PR, but it seems not possible on Github.
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