# Robotics Stack Exchange Community Digest

## Top new questions this week:

### Compute Maximum End Effector Velocity Along Path

Let's say I have a 2-link planar robot arm. The motors in both joints have maximum angular speeds that limit how fast they can spin. If I plan a path from point A to point B with a constant end ...

robotic-arm inverse-kinematics path-planning
 answered by Ugo Pattacini 1 vote

### Range of a heading angle [0,2π) or [−π,π)

Consider the unicycle dynamics in 2D plane: $$\begin{array}{l} \dot x = v\cos \varphi \\ \dot y = v\sin \varphi \\ \dot \varphi = \omega \end{array}$$ What is the range of the heading angle $\phi$? ...

mobile-robot kinematics dynamics coordinate-system

### Are all micro-nanorobots are 4D printed (TPP)?

I wanted to ask if there is another way to fabricate micro-nano soft robots apart from 4D printing. What are other fabrication methods can be used to build a soft microrobot?

soft-robotics

### Difference between CHOMP and DRL

in terms of motion planning, what are the difference between gradient-based motion planning (for instance, CHOMP http://www.nathanratliff.com/thesis-research/chomp) and deep reinforcement learning? ...

mobile-robot robotic-arm motion-planning reinforcement-learning

### What should be my spray handle-servo interface for pull mechanism?

I am an electronics engineering student who recently started working on Arduino. As part of my efforts to wake up on time, I decided that I should make an automatic water spray alarm clock. I have all ...

servomotor mechanism
 asked by Prasanjit Rath 1 vote

### Calculate Torques & Forces From Jacobian Matrix

Dear Robotics Stack Exchange, I am trying to calculate the torques and forces for a 2DOF robot. I’m used the partial differentiation method to find the Jacobian matrix. I managed to find the ...

robotic-arm kinematics torque jacobian force

### Uniform and non-uniform cost maps

I can not find a clear answer on the internet about the difference between a uniform and non-uniform cost map. I am interested in getting an answer in the context of grid maps for robot navigation.

mapping occupancygrid

## Greatest hits from previous weeks:

### Particle filters: How to do resampling?

I understand the basic principle of a particle filter and tried to implement one. However, I got hung up on the resampling part. Theoretically speaking, it is quite simple: From the old (and ...

localization particle-filter

### How to rotate covariance?

I am working on an EKF and have a question regarding coordinate frame conversion for covariance matrices. Let's say I get some measurement $(x, y, z, roll, pitch, yaw)$ with corresponding 6x6 ...

kalman-filter

### Is configuration space same as joint space?

For robotic manipulator like the one on the picture: are the configuration space and joint space equivalent? I am trying to understand difference between the two...

kinematics motion-planning forward-kinematics

### Simple equation to calculate needed motor torque

Suppose I have a DC motor with an arm connected to it (arm length = 10cm, arm weight = 0), motor speed 10rpm. If I connect a 1Kg weight to the very end of that arm, how much torque is needed for the ...

motor torque

### Which type of actuator will be suitable for a very strong robot arm?

I wish to build a robotic arm that can lift a useful amount of weight (such as 3-6 kg on an arm that can extend to approx 1.25 meters). What actuators are available to accomplish this? The main ...

mobile-robot robotic-arm actuator

### How do I calculate the required loop frequency for a servo controller?

I have a motor which drives a string connected to a load cell. I would like to implement a closed loop controller to control the load applied by the motor to the string. How do I go about determining ...

control motor force

I'm trying to find where additional battery capacity becomes worthless in relation to the added weight in terms of a quadcopter. Currently with a 5500 mAh battery, 11.1V, I can get between 12 minutes ...

## Can you answer these questions?

### Convert ECEF Velocity to NED Velocity

My GNSS modules gives me one NMEA packet with ECEF velocity. My doubt is about how i convert these 3 vectors to NED frame. Can i use the conventional matrix rotation MathWorksRef. If yes, i use the ...

 asked by Bruno Otavio 1 vote

### Use 2 Cameras as 1 Stereo Camera

I have one Picamera and one normal USB Webcam and would like to use them together as one stereo camera. Is this even possible as the 2 cameras aren't exactly the same? I would like to use them in ROS ...

ros slam cameras stereo-vision monocular

### Self localization for 3 wheeled omnidirectional robot

I am trying to self localize a 3 wheeled omni directional robots using just motor encoders I followed the odometry method mentioned in equations 5,8,9 of https://bibliotecadigital.ipb.pt/bitstream/...

localization odometry
 asked by Abhinandan K 1 vote
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