# Yiping Liu

### MathWorks

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**Content Feed**

robot simulation collision detection

It looks like you still want a robot model but just want to stay away with the DH parameters. You can use rigidBodyTree without ...

4 months ago | 1

Specify the RRT goalState as a matrix rather than a vector?

Hi, Chen, Thank you for your interest in this feature. It looks like that you are looking for the support of goal region in the...

4 months ago | 0

Building a map from Lidar Data with SLAM

You can use the example linked below to see how get streamed lidar readings from Gazebo into MATLAB. https://www.mathworks.com/...

4 months ago | 1

Velocity Product Torque Notation

Juraj, If you compare the EOM with the detailed Lagrange formulation, you will find both notations are correct. If you use the...

4 months ago | 1

| accepted

Is there a way to create a Dubins path given a set of waypoints?

Please check the example in the doc page below https://www.mathworks.com/help/uav/ref/uavdubinsconnection.html

6 months ago | 0

Is there a bug in show function of Robotics System Toolbox of 2021a version?

So the plot from 20a (LEFT) is incorrect, and this bug has been fixed in 21a (the plot on the RIGHT shows the correct joint ax...

6 months ago | 0

| accepted

matrix determined by eul2rotm does not match a matrix calculated by euler angles using rotm2eul

When you feed in a rotation matrix to rotm2eul, if the matrix is not orthonormal, the rotm2eul will try to find the closest orth...

6 months ago | 0

When I change joint type to fixed, it still appears in the robot configuration with NaN value. Why does it happens?

Hi Valerio, So this turns out to be a bug in the replaceJoint method (some internal numbers are not updated correctly when you ...

7 months ago | 1

| accepted

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...

7 months ago | 1

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.

7 months 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...

7 months 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 ...

8 months ago | 1

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...

8 months 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...

8 months 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...

9 months 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...

9 months ago | 0

| accepted

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...

9 months ago | 2

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,...

10 months ago | 0

| accepted

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.

10 months 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...

10 months ago | 1

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...

10 months 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...

10 months ago | 0

| accepted

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...

10 months 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...

10 months 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...

12 months 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...

12 months 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...

1 year 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...

1 year 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...

1 year 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...

1 year ago | 0

| accepted