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# Yiping Liu

### MathWorks

24 total contributions since 2019

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Measuring internal forces in a rigidBodyTree
By "internal force", I think you mean the constrained forces experienced by the joints. The recursive Newton-Euler algorithm doe...

alrededor de 5 horas ago | 0

How to set the center of mass of a prismatic joint?
The center of mass is a property on the rigidBody object and is not related to what type of joint this rigid body has.

15 días ago | 0

| accepted

Question regarding quaternion conventions; particularly with respect to point vs frame rotations
Your understanding seems to be correct. If the quaternion q reprsents a 3D rotation that rotates frame Local into frame Body, t...

17 días ago | 0

inverseDynamics function in Robotics System Toolbox gives wrong results for joint torque calculations for external force applied on the end effector of the robot
Hi, Hakan, Thanks for raising the questions about the external forces in rigidBodyTree inverse dynamics. The quick answer is ...

27 días ago | 0

Non-convex shape as a collisionBox for robot path planning
The CollisionMesh is designed to convert any unconvex mesh into its convex hull. The reason for that is the checkCollsion functi...

27 días ago | 1

How to solve inverse kinematic problem in real-time?
In 21a, RST introduced a new IK solver called analyticalInverseKinematics which allows you generate a closed-form IK function fo...

alrededor de 1 mes ago | 1

| accepted

How Does InverseDynamics Calculate Torques if Velocity is 0?
As described in the doc page, jointTorq = inverseDynamics(robot,configuration) computes joint torques to hold the specified r...

2 meses ago | 0

Using geometricJacobian and velocities
To your questions: NO. rigidBodyTree in Robotics System Toolbox is designed to be stateless. So there are no joint positions/ve...

2 meses ago | 0

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Robotics toolbox - strange results when using inverse dynamics and robot created with DH
Hi, Francesco, I think this is related to an issue that is specific to robot specified through DH parameters. This issue has al...

2 meses ago | 1

How to obtain end effector orientation angles respect to the global reference/fixed reference axes X0, Y0 and Z0?
In general, the intrinsic rotations Z−Y′−X'' by angles γ, β, α are equivalent to the extrinsic rotations X−Y−Z by angles α, β,...

3 meses ago | 0

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How to alter the roofed-section in MATLAB example (Track a Car-Like Robot using Particle Filter) for particle filter??
The roofed area is defined in ExampleHelperCarBot helper function.

4 meses ago | 0

| accepted

how to create a robot from DH parameters
Ali, the getTransform method is working correctly. But from the way you set the DH parameters, I assume you expect "theta offset...

4 meses ago | 0

Change base body of rigid tree robot.
You can check out the solution provided in this post: https://www.mathworks.com/matlabcentral/answers/696625-change-base-of-rig...

4 meses ago | 0

Why the result of Robotic System Toolbox are different with RTB(Robotics Toolbox for MALTAB)?
Hi, Xiyong, Thanks for posting this question. What you described is indeed a bug in the internal code for computing dynamics qu...

4 meses ago | 0

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Computing the Jacobian matrix of robot centroid.
Hi, Sheng, Thanks for posting this question. What you described is indeed a bug in the internal code for computing centroidal m...

4 meses ago | 0

| accepted

How to use inverseKinematics to find configuration to 1) get robot link to pass through position X1 in space and also 2) have end effector position X2?
Sounds like you are trying to solve a multi-constraint IK problem. You should check out the generalizedInverseKinematics feature...

4 meses ago | 0

change base of rigidBodyTree like in SerialLink
Currently there is not a user-facing way to modify the fixed tranform on the robot base - it's always assumed to be at the origi...

5 meses ago | 0

| accepted

Can I do a kinematics redundancy by using inverse kinematics?
You sould not use orientationTarget for link1. Try something like below (You only need pose and joint constraints) lbr = impor...

5 meses ago | 0

Simulation pick and place operation on 3 dof robotic arm in matlab environment.
Here are a variety of related examples you can refer to: Manipulator Motion Planning Manipulator Trajectory Generation and Fol...

6 meses ago | 0

output D-H parameters in Rigid body tree
If you import your rigidBodyTree from URDF, in general it cannot be converted to the standard DH representation without alternat...

6 meses ago | 0

Is it possible to call a rigidBodyTree robot model in a Matlab function in Simulink?
Lorenzo, the persistent variable is the correct way. You should also check out the rigid body tree algorithm Simulink blocks i...

6 meses ago | 0

| accepted

Error generating code for matchScans() function.
The error from matchScans during cross-platform codegen (like from Windows to ROS target) has been fixed in 20b release. If you...

8 meses ago | 0

| accepted