# Tag Info

4

The original manipulators referred to in that article were through-the-wall pantographs which moved radioactive materials without the human operator having direct contact with those materials. The end effectors of those manipulators did have direct contact with the materials - just not the human. Although the article is not specific about this, it seems ...

3

The interpretation of error for a robot manipulator pose is subjective in terms of what is the error being used for. A robot manipulator pose is combination of both position (x, y, z) and the orientation (quaternions or euler angles) and thus, designing the error could partially or completely include all terms. Your representation of error is essentially ...

2

In general i would say there is not enough information on this drawing, so we all ASSUME. If you look at this and assume it is a multicopter with 2 counter rotating propellers (can not fly in a normal fashion without a pivoting mechanism, like a Chinook) you can only have yaw, roll and up down control which makes for 3-DoF. For the arm it give you 2 DoF (...

2

There are 2 main rules in assigning frames following DH convention: source: Robot Modeling and Control, Spong et. al $x_i \perp z_{i-1}$ $x_i$ intersects $z_{i-1}$ In your attempts, Your first attempt is incorrect as your $z_2$ axis is not in the direction of actuation of the prismatic joint. I'm not clear on your second attempt as $x_1$ appears to be ...

1

Kinematics is based on geometry and joint constraints, so no change there at all. Dynamic motion results from the sum of forces, so the only change to a dynamic analysis is that you don't include gravity, but all other forces would remain.

1

Seems that the book has an error. You are right, they should correct that. In the drawing it can be seen that those two z-axis are indeed parallel. I recommend that you considered them parallel and try to draw them to see that it fits with the image.

1

I answered a similar question DH parameters for a PPP arm, take a look for a detailed answer. If your first joint is the origin, you start the parameters by looking to the next joint. In this case, the last line of the table will give you the parameters of the transformation between the last joint and the end effector. For your RRP arm, the DH parameters ...

1

When the manipulator's tool position $p_\text{tool} = (x_\text{tool}, y_\text{tool}, z_\text{tool})$ is different from the point $p_\text{target} = (x_\text{target}, y_\text{target}, z_\text{target})$ where the manipulator should go to, we say there is position error. Intuitively, position error $e$ should tell us how far the current tool point $p_\text{... 1 Yes, you can use any kind of algorithm to control a system. However, I wouldn't suggest preferring a fuzzy logic based controller over PID just because it yields better performance! Because it is hard to prove, if not possible, the stability of the closed-loop system when there is a fuzzy logic controller in the loop. That is the reason why the fuzzy logic ... 1 The Robotics Toolbox for MATLAB has a CodeGenerator class which takes a serial-link robot model SerialLink expressed in terms of Denavit-Hartenberg parameters and generates efficient C code for all the dynamic terms: mass matrix, Coriolis/centripetal and gravity. It uses recursive Newton-Euler and the method of Orin and Walker, the equations are computed ... 1 You can try to do some optimization of your computations. Things you can try Simplify the expression in your symbolic computation program. In matlab for example this is done with the 'simplify' command. If you do not need a super high precision then change the variable type to a lower precision. For example change the double type to float, it will go from ... 1 Actually, in certain configurations you can have an infinite number of IK solutions. For example if joints 4, 5, and 6 are straight and inline as in your image. You can rotate joint 4 by$X$and 6 by$-X$to get the same end-effector pose. This is a great video on arm singularities which also shows this phenomenon nicely: https://www.youtube.com/watch?v=... 1 Do "configuration" and "pose" means the same thing? No. One of the most clear definitions of 'pose' that I've heard is in Peter Corke's Robotics, Vision and Control (RVC). It states that: "The position and orientation of a coordinate frame is known as its pose and is shown graphically as a set of coordinate axes. The relative pose of a frame with ... 1 Imagine that you hold a position very stiff in your arm. You are holding your muscles tight to keep that position and hold it very tightly. Then you walk to move your arm without moving your arm with your arm muscles and crash into a wall. You will hurt yourself cause you tried to go there very stiff and didn't care what you would came in contact with as ... 1 A degree of freedom doesn't necessarily need to be continuous. We can easily define a system that has a discrete degree of freedom. For example, image a mobile robot in$\mathbb{R}^2\$ with a heat sensor. If the temperature is greater than 37 degrees celsius, we consider it to be hot. From 15 degrees to 37, we consider mild, and below 15, cold. In this way we ...

1

I'm not a fan of DH parameters but they are entrenched in robot kinematics. An approach I prefer is to just write the whole chain as a series of simple transformations, eg. Ry is a rotation about the y-axis, Tz is a translation along the z-axis. From your figure, starting at the base and applying the transformations consecutively, you could write it like ...

1

For a robot with a kinematic model expressed using standard DH parameters the classic reference is: Differential Kinematic Control Equations for Simple Manipulators, Paul, Shimano, Mayer, IEEE SMC 11(6) 1981, pp. 456-460 This is implemented in many software tools include the Robotics Toolbox for MATLAB as the method jacobe which gives the Jacobian for ...

Only top voted, non community-wiki answers of a minimum length are eligible