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Questions tagged [force]

Quantity causing acceleration in the state space of a mechanical system.

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Spring-Loaded Link/Joint in Robot URDF

I'd like to make a link/joint spring-loaded in my URDF, so that it takes a certain level of force to displace it and so that it returns to a base/equilibrium position when not in contact with anything....
S. Gun's user avatar
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Force torque sensor - ROS Noetic

I`m trying to add force torque sensor on wrist to this robotic arm. I add this code to urdf file ...
user1214542's user avatar
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acceleration input to quadcopter

I am new to quadcopters. My physics/mechanics has always been weak. I need help to clear this doubt. I am working on a project where i need to control my quadcopter by giving it acceleration input in ...
V Adarsh's user avatar
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Is it acceptable to convert the optimized control input state (acceleration) from my Model Predictive Controller to position

Good day, I hope you are well. I currently have an MPC position controller that optimizes a set of control input accelerations given a trajectory. u = [Ux_dot_dot Uy_dot_dot, Uz_dot_odt] However what ...
user123456098's user avatar
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1 answer
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Force transformation problem

I have the following set-up: I read force and torque values in sensor frame, but I want to transform the to tool frame. I have the following equation: where: This last matrix shoul be 6x6, but if I ...
Unai Granados Ormaetxea's user avatar
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21 views

Small 6 Axis Force Torque Sensor

currently I need to install an suitable 6 Axis Force Torque Sensor on my Robotic arm. It has to be small beacause it will be mounted on this Robot: https://www.wlkata.com/en-de/pages/pg-mirobot-intro ...
DomiBlack2k's user avatar
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How are exoskeletons controlled?

It is my understanding that there are 3 fundamental control methods : velocity, position and torque. In exoskeletons meant to augment an healthy user's strength, a typical control method used is ...
Kristof's user avatar
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1 answer
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How to compute the force applied to point P given the torque registered by the sensor?

I have the following set up: I want to understand how to compute the force that is being applied to the F_knife point given the Force/Torque registered by the sensor at T_Sensor. The position vector ...
cambel's user avatar
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Principal approach to control force of an electrically driven friction based griper

I would like to build a gripper that can pick and place irregularly shaped objects, for example, vegetables. I'd like to grasp the object with enough force so that it does not slip form the jaws, but ...
psarka's user avatar
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27 views

How to find coefficient of friction that will maximize torque?

When using DC motors with a drive wheel (aka "direct drive") to propel a vehicle (e.g. an RC car), force and torque play a role in how efficiently that motor's power is transferred into ...
tniles's user avatar
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How to Implement a Physically Human-Controlled Robotic Arm?

I'm a complete beginner in robotics other than FIRST competitions at my school. I wanted to make a robotic arm that works by a person physically moving the end-effector in 3D space and the robot ...
okayatcp12's user avatar
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69 views

Force sensors output when inclined

So here is the context: I am working on a motorcycle simulator. It consists of a motorcycle frame mounted on different actuators (see picture on the left). In particular, the two actuators at the ...
Pauline's user avatar
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512 views

Computation of centrifugal and Coriolis matrix

So I have a seesaw-cart electromechanical system which I want to control. It has 2-DOF (the angle of the seesaw $\varphi$ and the cart position $s$). I used the Euler-Lagrange method to get my ...
BigDuckPlaya's user avatar
2 votes
1 answer
1k views

IMU gravity sensing

How are IMUs used to sense the direction of gravity? I have read a number of articles that talk about using IMU for orientation of flying robotics but I do not understand how. Could someone explain ...
FourierFlux's user avatar
1 vote
1 answer
889 views

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 ...
Neamus's user avatar
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Center of Mass of a Box

If I have the following area-split box: Depending on the mass distribution of the box, the center of mass (CM) could be inside the light gray area labeled A, the red area labeled B, the blue area ...
Ammar Taha's user avatar
1 vote
1 answer
94 views

Force-torque sensor reading when a robot is stationary

Let's say I have a robot arm with a force-torque sensor on the wrist, between the final motor and the gripper. If the arm and wrist are stationary, then what would the reading on the sensor be? I know ...
Karnivaurus's user avatar
5 votes
2 answers
3k views

Impedance Control vs Position Control

I have been reading up on impedance control, and several sources have stated that it is much safer than position control. However, frustratingly, none of these sources have explained why this is. So......
Karnivaurus's user avatar
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2 answers
909 views

Quadrotor dynamics: How is torque created

I'm a software engineer and I've recently engaged into Robotics field. I've started by a course on Coursera which talks about Aerial robotics and thus quad-rotors. I'm trying to understand how quad-...
Mssm's user avatar
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2 votes
1 answer
303 views

Can I measure torque from this motor by only measuring the current?

I am new to robotics, please forgive/correct any errors. My Project Plan I want to use a PID controlled motor in a human-interface device where I need to measure the user's exerted force on an end ...
sgbrown's user avatar
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When not to use pseudoinverse?

I know this equation: $\tau = J^T f$. In my case, the Jacobian $J$ is not square. Is it valid to use the pseudoinverse of $J^T$ to calculate end effector forces $f$ based on joint torques $\tau$? I ...
Lemonbonbon's user avatar
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1 answer
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Force control on UR5e using moveit

For my project, an UR5e needs to follow a spline. At the end of the spline is needs to move into a certain direction with a constant force. The spline is succesfully executed using the cartesian path ...
user avatar
5 votes
1 answer
550 views

Understanding Impedance Control

I have a question regarding impedance control for a robotic manipulator. Given that we have a task space trajectory: $\ddot{x}$, $\dot{x}$ and $x$ And the dynamics model of the robot: $$\tau = M(q)\...
Spaceman's user avatar
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Singular Configuration - Balanced Wrench F?

I've been asked to show that if a manipular is at a singular configuration, then the End Effector wrench can be balanced without any joint torques. I know that t = J*F where (t = torques, F= end ...
raaj's user avatar
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TypeError: expected [string] but got [gazebo_msgs/ApplyBodyWrenchResponse]

I use rosservice to drive the rrbot model, python code is as follows: ...
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5 votes
1 answer
2k views

Why do we need coriolis and centrifugal forces when it comes to the dynamics of a robotic arm?

So we all know (and love) the typical dynamic equation of a robotic arm: $$ M(q) \ddot{q}+C(q,\dot{q})\dot{q}+G(q)=\tau $$ Where M is the mass matrix, G is gravity and C is Coriolis and Centrifugal ...
Metalzero2's user avatar
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1 answer
25 views

which file implements the husky_velocity_controller?

When I controll the husky simulator, the motion of husky is driven by the /husky_velocity_controller/cmd_vel, I send a cmd_vel topic as expected velocity, the robot moves. But from physics, we know ...
user avatar
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1 answer
9 views

where is the controller from /cmd_vel to the force applied to robot?

It seems to me that what ros provides us to control a robot is the expected velocity /cmd_vel, but from this signal to real force/torque applied to the robot, there must be a controller there. Can ...
user avatar
0 votes
1 answer
68 views

Compute vector of attraction plus repulsion forces in a 2D force field mapping

I'm developing a force field mapping of a two-dimensional space to move a robot to a goal avoiding obstacles. My problem is that I don't know how to move it using attraction force and repulsion ...
VansFannel's user avatar
3 votes
1 answer
64 views

Force controller with feedback issues

I'm implementing a force controller on a robotic arm, where the force input comes from torque sensors in the joints. I have calculated the cartesian force on the end-effector from the joint torques, ...
Ove Baardsgaard's user avatar
4 votes
1 answer
3k views

How to limit large acceleration and jerk from PID controller?

I am trying to control a robotic arm with force input. The output of the force sensor is filtered, and fed through a PID controller to command the end-effector velocity. However, the robotic arm has ...
Ove Baardsgaard's user avatar
2 votes
2 answers
2k views

Jacobian of a 6DOF arm

I have a robot with 6 DOF. I read a lot of tutorial on how to compute the Jacobian, but usually all examples are for planar robots with 2DOF. I don't understand how can I get the Jacobian of a 6 DOF ...
Jonathan F's user avatar
1 vote
1 answer
1k views

How to calculate effort/torque values of a joint

I have a robotic arm with 6 DOF. For each joint, I get get the Joint Wrench, which is composed by the force and torque of the parent and child links of the joints. In other works, for joint 1 I can ...
Jonathan F's user avatar
1 vote
1 answer
363 views

DJI E310 Thrust Coefficient

I am reading Denis M. Filatov et al.'s paper "Parameters identification of thrust generation subsystem for small unmanned aerial vehicles" (https://www.semanticscholar.org/paper/Parameters-...
John Smith's user avatar
0 votes
2 answers
24 views

Looking for an industry robot with joint velocity control

Hey All, Currently we are looking for an industry robot that accepts joint speed command for real-time force control. I know Universal Robot is a potential candidate. However, its payload is not ...
user avatar
0 votes
1 answer
559 views

Calculation of inertia values of Ic and Im

In my dynamic model of two wheeled mobile robot, it has the total equivalent inertia, noted $I$, described by the equation below, $I_c$ is the moment of inertia of the DDMR about the vertical axis ...
user19871's user avatar
3 votes
1 answer
229 views

From a linear force actuator that spans multiple links and joints to the equivalent motor torque

I am programming/using a rigid body joint-space dynamics solver for robots in which I want to implement linear force actuators between links with their equivalent torque sources that are 'spanned' by ...
Retinite's user avatar
0 votes
1 answer
20 views

force torque sensor and control force values

Hi all, I'm using libgazebo_ros_ft_sensor.so plugin to find torques in joints and control joints using gazebo_ros_control plugin. However when I compare joint torque from sensor and ...
user avatar
0 votes
1 answer
53 views

Will this have more or less lifting strength

Bit of an engineering question. If a snake robot is 100 cm long, and every 10 cm is another motor. Would the robot lift more weight, the longer/more motors attached to it.. or is lifting ability ...
Carson's user avatar
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2 votes
2 answers
6k views

What is the torque/force required to rotate the base of a robot arm?

Take a look at the following simple example robot arm: I want to know the torque required on that bottom motor to rotate the arm. Since it's not exactly rotating directly against gravity like the ...
JDS's user avatar
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1 answer
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set constant speed for AUV on dynamic uwsim

I want to set constant speed for AUV, however, uwsim is dynamic which means I am only able to give force to the AUV's thruster and the AUV is influenced by the water's friction force. If I could make ...
user avatar
0 votes
1 answer
11 views

Need help to edit libgazebo_ros_bumper source

Hellor everybody I'm going to validate gazebo and ROS contact and 6 axis force/torque sensors. I have currently studied 6 axis force torque sensor using a simple inverted pendulum. I compared 6 axis ...
user avatar
0 votes
1 answer
99 views

Interpretation of Force/Torque Sensor using gazebo_ros_ft_sensor plugin

I've successfully added a force torque/sensor to my model by adding following codes in my urdf file: ...
user avatar
0 votes
3 answers
1k views

how to find maximum force of a robot joint

I want to know if there is any equation that calculates the maximum force of a robot joint. The force that we should not exceed. For example in human leg, if we apply a big external force to the knee,...
djou's user avatar
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1 answer
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Based on uwsim, is it possible to set the friction force of water for the auv?

Based on uwsim, is it possible to set the friction force of water for the auv? The auv would drift after the thruster was shut down. I want to set a friction force in order to make the auv stop ...
user avatar
0 votes
2 answers
10 views

Ros node does not recognize Haptic device

I am developing a ros node for reading Force Dimension Omega.x haptic device input. I downloaded the Force Dimension SDK, compiled the libraries and exported them in /usr/local/lib while copied the ...
user avatar
5 votes
2 answers
219 views

What are the best ways to transmit force through air efficiently?

I am taking part in a robotics competition, where the challenge is to create a pair of robots which successfully navigate a series of obstacles. However, the rules state that of the two robots, only ...
Vaibhav's user avatar
  • 61
2 votes
2 answers
172 views

Magnetic, low insertion force connector

I'm building a robotic tea-maker/watchdog robot and have a power problem. I would like to be able to have the robot approach a socket and insert the power cord of a cheap immersion heater (120V, 300W, ...
user avatar
2 votes
1 answer
574 views

Verifying motor selection calculations

I'm trying to select a brushed DC motor for a project. I tried following the advice on sizing electric motors, mentioned in this question, but a few details were missing, and I'm unsure if I properly ...
Cerin's user avatar
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1 vote
0 answers
31 views

Unilateral Torque Constraint on the foot-ground interface

I was studying the basics of legged locomotion and came across the unilateral force and torque constraints at the foot-ground interface. I understood the implication of the unilateral constraint on ...
user3079474's user avatar