7
votes
Accepted
Is there a way to determine which degrees of freedom are lost in a robot at a singularity position by looking at the jacobian?
Not by merely looking at Jacobian but by looking at the Singular Value Decomposition of the Jacobian, one can see the degrees of freedom that are lost, if lost. Of course it technically somehow turns ...
- 196
6
votes
Is there any robot stability control equation that describes the relation between velocity of the robot and its orientation?
That's not obvious. If I'm in a tank, going 0.5 km/h, I don't need to slow down at all. If I'm in a bobsled going 100km/h and the track banks, I don't need to slow down at all.
When you steer, you ...
- 15.7k
6
votes
Accepted
Extended Kalman Filter in robotics - Worth it?
The Kalman filter is an optimal linear filter in the presence of Gaussian noise. It is optimal in the sense that it minimizes the mean-squared error. This means that the covariance of the estimated ...
- 340
5
votes
What is the difference between a CNC router versus a CNC mill?
TL;DR CNC routers move the tool while CNC mills move the workpiece, but this is a matter of common usage and not based on hard definitions.
A router (in the woodworking sense) is just a rotary tool ...
- 11k
5
votes
Accepted
Comparing industrial robot arms
For example, how does price vary with precision, speed, reach and
strength?
The price vary a lot, from a couple of hundreds of bucks to hundreds of thousands of dollars ( Willow Garage's the one-...
- 168
4
votes
What is the best software/package to draw the robot manipulator and indicate DH parameters and different axes?
Use RoboAnalyzer. It will help you understand what you need.
- 91
4
votes
What is the difference between a CNC router versus a CNC mill?
Not a big fan of using head motions or type of spindle to define the difference, as there are lots of exceptions to each. Many 5-axis mills move the head in various ways beyond just Z. Datron makes ...
- 71
4
votes
Accepted
How are huge industrial robots powered?
Industrial Robots with having as aim manipulation of large objects are powered electrically in almost all cases (30-40 years ago there have been popular hydraulic variants).
Industrial robots are ...
- 6,612
4
votes
Accepted
Do you have to stop a programmable logic controller to update its logic?
The function you are looking is called online change (e.g. Beckhoff Online Change), at least by some PLC Manufacturers. If you change a few blocks (in case of FBD) or a few contacts (in case of LAD) ...
- 6,612
4
votes
Accepted
Definition of payload for industrial robots
If you only consider the simple physics of the problem you are completely right, it should be able to move lower payloads at lower velocities and accelerations.
However, the maximum payload can only ...
- 6,612
3
votes
How are industrial robotics components purchased?
For an industrial setting funds are not unlimited but the value of the machine to the process is known or predicted and if the benefit is greater than the cost, the funds are sought.
Relationships ...
- 4,335
3
votes
Accepted
Implementing an analytic version of an inverse kinematic
Given a desired pose:
$$T^{desired} = \begin{bmatrix}
s_x&n_x&a_x&P_x\\
s_y&n_y&a_y&P_y\\
s_z&n_z&a_z&P_z\\
0&...
3
votes
Implementing an analytic version of an inverse kinematic
Your Jacobian-based approach is great for velocity control, or when the manipulator is close to the original point. But remember, the Jacobian only gives a first-order approximation to the ...
- 4,366
3
votes
What is the difference between a CNC router versus a CNC mill?
On a typical CNC router, the work is stationary and the spindle-head moves in x/y/z coordinates.
On a typical CNC mill, the work moves in x/y coordinates (ie, is attached to an x/y table) and the ...
- 1,981
3
votes
What is the easiest and efficient way to detect human in close range distance and make the robot follow it?
Following a human can be relatively easy, but it depends on your requirements and your sensors on how easy this is. If you use ROS there are some available packages:
people_tracker which uses a ...
- 260
3
votes
Accepted
Linear actuators in a cartesian robots
I have worked on a cartesian robot with similar requirements† as your own, and we selected direct drive synchronous linear motors for our x/y stages. In our case, both axes were around 2m in ...
- 4,203
3
votes
Denavit-Hartenberg convention or the product of exponentials formulation, when dealing with the manipulator kinematics?
They are two different ways of getting the same thing. Correctly set D-H parameters will give the exact same kinematics and dynamics as correctly set POE parameters. There are well-defined (although ...
- 2,764
3
votes
Accepted
Implementing a torque-controlled method on a position-controlled robot
We find this recent paper by Andrea Del Prete, Nicolas Mansard, Oscar Efrain Ramos Ponce, Olivier Stasse, Francesco Nori quite interesting:
Implementing Torque Control with High-Ratio Gear Boxes and ...
- 1,819
3
votes
Accepted
Industrial Controllers - Why not adaptive control and robust control
In short, adaptive control and robust control (Hinf) are the difficult combination of computationally expensive and complicated to understand. Even if you do an excellent job of implementing one of ...
- 2,764
3
votes
Industrial Controllers - Why not adaptive control and robust control
If I had to guess, I would say that, in an industrial setting, you have a relatively high degree of certainty about the process you're controlling, and/or there isn't much emphasis on transient ...
- 15.7k
3
votes
Accepted
How do I model a simple robot arm as a plant?
Each joint of your robot is one motor. They are coupled though kinematic relations and dynamic physics.
One straight forward way is to derive these so called 'equations of motion' using the euler-...
- 189
3
votes
Accepted
Creating linear end effector motion using joint speeds: Converting tool speed to joint speeds
Joint velocities and tool velocities are directly related through the following equation
$$
\dot{x} = J(q)\dot{q},
$$
where $\dot{x} \in \mathbf{R}^6$ is the tool (linear and angular) velocities, $\...
- 1,819
3
votes
Accepted
Gravity compensation
In an ideal scenario, yes, that should be the case. When gravity compensation is implemented on robots, all joints apply a torque to balance out the torque applied by the force of gravity. They should ...
- 671
3
votes
Accepted
Position vs Image based visual servoing?
The problem in both cases is to move the robot tool to some pose relative to an object. Let's assume the camera is attached to the end of a robot arm (eye in hand case) so we will consider this a ...
- 1,652
3
votes
What should be the ideal ratio for link lengths ( L1/ L2) of a 2 link manipuator robot with revolute joints?
This is a good question, and one you should definitely consider when designing a new robot arm. But unfortunately, it depends a lot on the configuration of your arm (i.e. how the joints will be bent),...
Ben♦
- 5,780
3
votes
What is the meaning of joint space and configuration space and task space?
All "spaces" are used to define the current state of the robot, but with differences. The state of the robot is a point (also known as a configuration or pose) in a space. Please note that ...
- 6,612
3
votes
Accepted
Articulated Body Algorithm with gear ratio
In Featherstone's book "Rigid Body Dynamics Algorithms", there is a section of Chapter 9 (specifically, 9.6) dedicated to explaining how to incorporate gears into a given dynamic model.
At a ...
2
votes
How to implement PID control for robotic arm?
There are at least two different ways to get it:
Explanation 1)
For a very special class of mechanical systems like the robotics manipulator, the control law $u=-K_pe+g(q)$ with $K_p$ symmetric ...
- 166
2
votes
How to implement PID control for robotic arm?
As @acs said, PID control is used for individual joint control. And you ignore all non-linearities. And typically this is good enough. Sure each joint's control isn't completely optimal, but they ...
Ben♦
- 5,780
2
votes
Denavit-Hartenberg convention or the product of exponentials formulation, when dealing with the manipulator kinematics?
I recently worked with DH parameters to define kinematics of my Dual Arm Robot. As per my knowledge and experience, for kinematics I can say that DH Param will be good to use it since that gives you ...
- 91
Only top scored, non community-wiki answers of a minimum length are eligible