Is there any way to create a weld joint during a simulation in Drake? For context, I am trying to get a robot to assemble furniture, and whenever it attaches two pieces of furniture (ie. a chair leg with its base), I want to weld them together.
I have attempted using LinearBushingRollPitchYaw, with large damping and spring constant values, but I was either not getting "welds" or there would be a segfault.
I have also thought about stopping the simulation, doing the weld, and restarting the simulation, but I was not sure if this was practical.
Is something like this possible in Drake?
Thanks.
Here's some related information:
https://github.com/RobotLocomotion/drake/issues/14200
https://github.com/RobotLocomotion/drake/pull/15137
https://github.com/RobotLocomotion/drake/issues/13291
Related
I want to enable a gripper to do pick&place an object from a shelf. For this, I am trying to use trajectry optimization using KInematic Trajectory Optimization and I am using this deepnote. But the problem is when I add an object to the plant, also the object is considered in the optimization prog. How can I exclude this object from being considered in the optimization.
I am kinda new to the drake and I kinda don't know how to exclude an object from conraints.
Thanks in advance, I am kinda in rush :)
drake
Short answer: I think you want to create a separate MultibodyPlant to your KinematicTrajectoryOptimization that doesn't have the objects in it.
More generally, it's very common to have multiple plants flowing through your robot + control stack, e.g. one for the "robot model" and another for the "robot + objects in the world" model. (It's reasonable that the physics engine's model of the world would be different than the model in the head of the robot). Currently in Drake, it's more recommended to just load two independent plants, rather than try to add/remove objects from an existing plant.
I am using opencv and openvino and am trying to figure out when I have a face detected, use the cv2.rectangle and have my coordinates sent but only on the first person bounded by the box so it can move the motors because when it sees multiple people it sends multiple coordinates and thus causing the servo and stepper motors to go crazy. Any help would be appreciated. Thank you
Generally, each code would run line by line. You'll need to create a proper function for each scenario so that the data could be handled and processed properly. In short, you'll need to implement error handling and data handling (probably more than these, depending on your software/hardware design). If you are trying to implement multiple threads of executions at the same time, it is better to use multithreading.
Besides, you are using 2 types of motors. Simply taking in all data is inefficient and prone to cause missing data. You'll need to be clear about what servo motor and stepper motor tasks are, the relations between coordinates, who will trigger what, if something fails or some sequence is missing then do task X, etc.
For example, the sequence of Data A should produce Result A but it is halted halfway because Data B went into the buffer and interfered with Result A and at the same time screwed Result B which was anticipated to happen. (This is what happened in your program)
It's good to review and design your whole process by creating a coding flowchart (a diagram that represents an algorithm). It will give you a clear idea of what should happen for each sequence of code. Then, design a proper handler for each situation.
Can you share more insights of your (pseudo-)code, please?
It sounds easy - you trigger a face-detection inference-request and you get a list/vector with all detected faces (the region-of-interest for each detected face) (including false-positive and false-positives, requiring some consistency-checks to filter those).
If you are interested in the first detected face only - then it could be to just process the first returned result from the list/vector.
However, you will see that sometimes the order of results might change, i.e. when 2 faces A and B were detected, in the next run it could still return faces, but B first and then A.
You could add object-tracking on top of face-detection to make sure you always process the same face.
(But even that could fail sometimes)
I am working with a diagram which includes a MultiBodyPlant with a Propeller connected to it. The Propeller actually realizes numerous physical propellers which are distributed among the bodies of the MultiBodyPlant.
I am able to simulate the dynamics of the combined system by setting the prop forces with FixValue, so I'm on the right track.
What I'd like to be able to do is, given a configuration for the system (i.e. the MultiBodyPlant context) and a chosen propeller command, compute the generalized forces acting on the system. My sense is that this is not immediately available since the simulation is actually using the RNEA, and so does not aggregate the forces all together in that way. For what I'm doing (and even just as a sanity check), I would like to compute the forces directly, not just their effect on the evolution of the state.
Is there an existing method to compute this built into Drake, or should I compute it manually using the spatial jacobian of each propeller frame and the applied SpatialForce of the corresponding propeller? (Something along the lines of this question: How to get the matrix that maps external forces to generalized forces?)
Many thanks for your help.
I understand better now. It's a very reasonable request! You have two systems at play: the Propeller and MultibodyPlant. Unfortunately, the quantity you want is all of Propeller and just a piece of MultibodyPlant. We don't offer direct access to the B(q) matrix in that case.
What you can do is call with either AutoDiffXd or symbolic::Expression, call CalcImplicitTimeDerivativesResidual on the Diagram to get the entire dynamics in implicit form (to avoid taking M(q) inverse). You could call it twice -- once with the Propeller inputs set up via FixValue as AutoDiffXd and/or symbolic::Variable and again with them as zero, then subtract the difference.
Note: CalcImplicitTimeDerivativesResidual is relatively new; I haven't pushed the python bindings for it yet (but it's been on my list). Do you need it from python?
I think that perhaps you are looking for the MultibodyPlant reaction_forces output port?
Background:
I got a unidirectional planner graph, each node in the graph contains its location and to which nodes it's connected to(up to 4 nodes each one in a separated variable).
Each connection between nodes is an edge, a road segment and each node is a junction\dead end.
The road should follow a 2D polar grid layout and will be edited in runtime.
This will be used as a road-building tool for city building game.
I'm using UE4 C++ and I'm pretty new to procedural generation.
The issue:
I'm looking for some guidance on how to generate the topology.
1. What algorithms\method\technic\math I should use or know about?
2. If I should use the extrude method then how do I include the junctions?
3. Where should I have overlapping verts? (other then places where I need to cut for UVs)
4. How do I incorporate sidewalk to the road segments and the junctions
Research:
The best way that I found is basically the extrude method which seems too primitive and will be problematic with intersections since it requires to lookup verts locations which seems extremely inefficient.
More details about the graph:
https://gamedev.stackexchange.com/questions/179214/generate-road-mesh-from-a-graph
(I'm posting here because game dev seems to be pretty dead sadly)
I'm trying to figure out the best way to analyse a grasshopper/rhino floor plan. I am trying to create a room map to determine how many doors it takes to reach an exit in a residential building. The inputs are the room curves, names and doors.
I have tried to use space syntax or SYNTACTIC, but some of the components are missing. Alot of the plugins I have been looking at are good at creating floor plans but not analysing them.
Your help would be greaty appreciated :)
You could create some sort of spine that goes through the rooms that passes only through doors, and do some path finding across the topology counting how many "hops" you need to reach the exit.
So one way to get the topology is to create a data structure (a tuple, keyValuePair) that holds the curve (room) and a point (the door), now loop each room to each other and see if the point/door of each of the rooms is closer than some threshold, if it is, store the relationship as a graph (in the abstract sense you don't really need to make lines out of it, but if you plan to use other plugins for path-finding, this can be useful), then run some path-finding (Dijkstra's, A*, etc...) to find the shortest distance.
As for SYNTACTIC: If copying the GHA after unblocking from the installation path to the special components folder (or pointing the folder from _GrasshopperDeveloperSettings) doesn't work, tick the Memory load *.GHA assemblies using COFF byte arrays option of the _GrasshopperDeveloperSettings.
*Note that SYNTACTIC won't give you any automatic topology.
If you need some pseudo-code just write a comment and I'd be happy to help.