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Questions tagged [drake]

Drake is an open-source toolbox for planning, control, and analysis of nonlinear systems, developed in C++ with bindings available in Python.

Drake is an open-source toolbox for planning, control, and analysis of nonlinear systems, developed in C++ with bindings available in Python.

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692 questions
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What is the correct way to run a pydrake simulation "online"?

In Drake/pydrake, all of the examples I have seen create an instance of Simulator and then advance the simulation by a set duration, e.g. sim.AdvanceTo(10) will step the simulation until it has simulated 10 seconds of activity. How can I instead run…
adamconkey
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Numerical roundoff error in bilinear alternation leads to infeasibility

We are trying an alteration optimization strategy to solve Lyapunov problems. We break down our decision variables into two sets, Set 1 and Set 2. We were perplexed how it was possible that, after getting a solution to Set 1, and plugging in those…
HoliInn
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Can I save a MultibodyPlant into URDF (or other supported xml type file)?

For example I can build a model using functions like AddRigidbody and AddJoint. After the model is built, can I save the model into a URDF file or other xml type file? Drake can load model from URDF or SDF using parser but I haven't find function…
Chen Wang
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URDF model keeps disappearing whenever I add intertial properties to a link? How can I resolve this issue?

I am trying to simulate a simple pendulum using pydrake and am having a couple of issues creating the urdf file to creat the model for the pendulum. I have no background knowledge on urdf or drake and am open to any suggestions to resolve this…
Raviverma Chamarti
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Base component of Spatial Velocity Jacobian for a Free-Floating Base Robot is all Zeros

I am trying to find the end-effector spatial velocity Jacobian for a robot with a free-floating base. Due to the free-floating base, the jacobian should contain a base component and a manipulator comment (see…
Shubham Vyas
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Acceleration/Jerk level constraint for trajectory optimization using Direct collocation

I would like to know if there is an elegant way to impose acceleration/jerk level constraint on the trajectory optimization using the DirectCollocation class. I am working with an Acrobot system, and I have already included the velocity level…
Mahdi Javadi
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Finding the Jacobian of a frame with respect to the joints of a given model in Pydrake

Is there any way to find the Jacobian of a frame with respect to the joints of a given model (as opposed to the whole plant), or alternatively to determine which columns of the full plant Jacobian correspond to a given model’s joints? I’ve found…
JoshuaF
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How to deal with the algebraic loop in Drake?

I wrote the code for a linear system and a simple state feedback controller in Drake, but when connecting the two systems, the following error message appeared, RuntimeError: Reported algebraic loop detected in DiagramBuilder:. Then, I replaced my…
Luyao
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Best method to add generalized forces to Linearized (or LQR) MultiBodyPlant?

I'm trying to add generalized forces on a free-floating system that has been linearized from a MultiBodyPlant. For a fixed base, the generalized forces basically correspond to the joint torques but for a free-floating case, it includes the base…
Shubham Vyas
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how to get a dynamic which we can be applied gradient in the next step (re-open)

I want to ask a question related to a workflow like this: 1.obtain manipulator equation of multibody plant, 2.re-write it to a form of qdd = f(q,u), 3.calculate next state(x_next), 4.calculate the gradient of x_next w.r.t x and u. I find the most…
Wc Chang
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Where does the get_input_port method reside in drake?

I'm trying to find the template function that this call is referring to https://github.com/RobotLocomotion/drake/blob/master/examples/pendulum/pendulum_geometry.cc#L102 const auto& input =…
cjds
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Import Error on importing pydrake.multibody.math

I'm trying to import SpatialForce for my code but it keeps failing with the error ImportError: C++ type is not registered in pybind: N5Eigen14AutoDiffScalarINS_6MatrixIdLin1ELi1ELi0ELin1ELi1EEEEE Simply running from pydrake.multibody.math import…
Mark
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Is Drake obeying joint limits in this case and how can I check?

I'm trying to understand if Drake is following joint limits in this simple example. I have this URDF
cjds
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How do I set the friction properties (or any GeometryProperties) of a specific body in MultibodyPlant?

I would like to know how I can set the frictional properties of a body in MultibodyPlant. More specifically, I have a model instance that has been read in from an SDF and I would like to add or change the friction properties of a particular body in…
samzapo
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How to get the matrix that maps external forces to generalized forces?

Given a multibody plant, I need to find the the matrix that transforms the external forces lambda into generalized forces. I.e. Phi in the following equation (taken from An Efficiently Solvable Quadratic Program for Stabilizing Dynamic Locomotion…
Rufus
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