24.05.20 Progress Meeting

[Woolfrey]

Chair:

@Woolfrey

Attendees:

@Woolfrey
@ssutjipto

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Announcements

• We're organizing to bring Shoudong to Leeds for a research collaboration. And he his expecting me to write control code for the robot. @ssutjipto can be the point of contact in Sydney.

Agenda

Note: Last week's actions become this week's agenda

Item	Responsible	Issue	Outcome
Create class member for joint damping vector	@ssutjipto	N/A	Done by @Woolfrey and @ssutjipto simultaneously?
Continue ActionServer base class	@Woolfrey	Link	Working on SerialKinematicControl and accompanying test script

Additional Discussion

Topic	Raised By	Issue	Outcome
Is the redundant control optimisation in the right order for the kinematic control class?	@ssutjipto	N/A	Order of arguments is incorrect, but it should be caught in compile or runtime.
In the track joint trajectory class, should first be solving for acceleration then compute torque	@Woolfrey	N/A	Put a comment in the code for @ssutjipto
It should be possible solve both acceleration & torque limits for joint trajectory tracking as a QP problem	@Woolfrey	#118	Not urgent, but would be nice to do.

Actions

Action	Responsible	Tag
Finish the test script for velocity level joint trajectory tracking	@Woolfrey	#116
Continue on action server	@Woolfrey	Link
Type up math for joint level feedback in discussion below	@Woolfrey	N/A
Continue working on dynamic control class	@ssutjipto	#117

[Woolfrey]

@ssutjipto here's the math for the trajectory tracking control problem:

$$\boldsymbol{\tau} = \mathbf{M\ddot{q} + C\dot{q} + g}$$

where:

$$\mathbf{\ddot{q} = \ddot{q}_\mathrm{d} + K_\mathrm{d}\left(\dot{q}_\mathrm{d} - \dot{q}\right) + K_\mathrm{p}\left(q_\mathrm{d} - q\right)}$$

versus:

$$\boldsymbol{\tau} = \mathbf{M\ddot{q}_\mathrm{d} + K_\mathrm{d}\left(\dot{q}_\mathrm{d} - \dot{q}\right) + K_\mathrm{p}\left(q_\mathrm{d} - q\right) + C\dot{q} + g}$$

In the latter case, if the gain matrices are diagonal, you will get poor trajectory tracking because of the dynamic coupling between the joints.

[ssutjipto]

I've corrected it now. I had placed and removed brackets in the wrong place.