Brandon J. DeHart
  • Member for 6 years, 5 months
  • Last seen this week
Angular momentum of rimless wheel in Passive Dynamic Walking
Accepted answer
4 votes

In McGeer's 1990 work on Passive Dynamic Walking, the angular momentum equation that you have posted is the angular momentum of the system just before the impact of the swing foot, about the impending ...

View answer
Comparing LQR and PID controllers for inverted pendulum problem
4 votes

You are correct in claiming that both PID and LQR can be applied to the linearized form of the cart-pole problem. If you have a look at the answers to the related question Ugo linked to in the ...

View answer
How to convert between classic and modified DH parameters?
Accepted answer
4 votes

Unfortunately it is not as simple as just shifting the a and alpha columns, as the locations of the frames and the directions of their axes can also change when moving from one DH formulation to ...

View answer
What are the best ways to transmit force through air efficiently?
3 votes

There are very limited options for effectively transmitting force across a distance, other than with projectiles of some kind which won't achieve your goals or be allowed under the rules. Based on ...

View answer
Stationary/inertial reference frame
2 votes

Due to the way that frames are defined in the Modern Robotics book (and in this type of vector-field mechanics in general, such as those of Featherstone), both the spatial frame and the body frames ...

View answer
Validation of dh parameters
Accepted answer
2 votes

The easiest way to validate a set of DH parameters is to plug them directly into a simulator which can build a robot model from a DH table. Once you've got the DH-generated robot model, you can verify ...

View answer
Electronic circuit for heating nylon fishing line muscle
2 votes

As far as how to heat the nylon muscles, one of the articles that you have linked to provides a number of methods for doing so. The two most promising from an experimental perspective are submersing ...

View answer
Dynamic model of a tank like robot
Accepted answer
2 votes

For building a dynamic model from scratch of any differential drive mobile robot (i.e., a tank), the best resource I've found so far is a paper by Dhaouadi and Hatab (PDF link) titled "Dynamic ...

View answer
what is difference between twist and classcial velocity
Accepted answer
1 votes

In these equations from Modern Robotics (by Park and Lynch), the fixed inertial frame ${b}$ is both the reference frame used to define all of the coordinate vectors and has its origin located at the ...

View answer
Inertial frame's angular velocity expression
Accepted answer
1 votes

My initial response would be that your angular variables are being measured in the opposite direction from the matrix in the slide you shared. In other words, theta should actually be negative theta, ...

View answer
Robotics Toolbox: Display all DH link frames in Seriallink.plot()
Accepted answer
1 votes

The easiest way to do this would be to use the trplot function (documented for v9 at http://www.petercorke.com/RTB/r9/html/trplot.html). You can simply call this function with the transformation ...

View answer
Inverse Kinematic for 3DoF chain with 2 links constrained together
0 votes

In general, when teaching my students how to do IK my first recommendation is always to find a variable (length/angle/value/etc) that is only a function of one joint so that they have one equation ...

View answer
perplexity about ch8.2.1 the linear dynamics, in the book <modern robotics>
Accepted answer
0 votes

To answer your first question: $v_b$ is the linear velocity of the centre of mass of the body relative to a fixed inertial frame coincident with the body frame with its origin at the centre of mass. ...

View answer
Multiple Rotations via Matrix Multiplication
0 votes

Something to remember about rotation matrices is that they have multiple applications (that each has a different role in rigid-body motion): representing an orientation relative to a reference frame, ...

View answer
Calculating wheel linear velocity from body velocity
Accepted answer
0 votes

The matrix you have termed the "mapping matrix" is meant to translate between the twist (linear and angular velocity) of the robot and the linear velocity of the centre of each individual ...

View answer
Help on the Walking without thinking about it paper!
Accepted answer
0 votes

I think you are correct that the equals sign in equation (33) should not be there, as reinforced by the first author's thesis. The purpose of those equations are to constrain the MPC-generated ...

View answer
How to derive the inverse kinematic equations for this simple 6-DOF robot?
0 votes

Since you are solving an Inverse Kinematics (IK) problem, you should already have the pose (position and orientation) of the end effector (EE) relative to the fixed base of the robot (or the pose of ...

View answer
Why do we say a robotic arm have 2 dof even though the two joints rotates along the same axis?
0 votes

The number of degrees of freedom any mechanism has (including a robot) is solely based on how many different ways there are to change its configuration (the position and orientation of every part of ...

View answer