Questions tagged [force]

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

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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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......
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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-...
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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 ...
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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 ...
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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)\...
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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-...
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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 ...
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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 ...
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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 ...
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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 ...
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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,...
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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 ...
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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, ...
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1 answer
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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 ...
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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 ...
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1 answer
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Calculating the force of this system

My native language is not English, so I don't know all the specific terms you may expect me to use. I apologize for that. Anyway, I have a motor and three connecting rods (in French, bielles). So ...
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6 votes
2 answers
265 views

Is there a rule of thumb for actuator torque overhead?

When installing a servo or other actuator, I measure the force needed to perform whatever action is needed and find an actuator that can generate more than the necessary force. However, I recently ...
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Dynamics of parallel manipulator

My task is to apply forces to control 3-dof parallel manipulator. Forces are applied to linear actuators, friction is neglected. End-effector of a robot is supposed to follow generated path; for ...
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Wind force impact on torque mechanical arm

I've got an arm attached to a shaft. The arms dimensions are 40x5 inches the arm weights about 10 lbs. If I have a wind acting on the side of the arm, how would I translate the wind force into torque ...
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Force measurement on grab bars [closed]

I recently start a project to measure the force on a bathroom grab bar. The force/load is applied by the person who need to the grab bar for assistant. What I want to measure is the load against the ...
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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 ...
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