# Questions tagged [dynamics]

Dynamics is a branch of applied mathematics (specifically classical mechanics) concerned with the study of forces and torques and their effect on motion, as opposed to kinematics, which studies the motion of objects without reference to its causes.

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### Can knowledge of robot's dynamics help in motion planning?

Some planners assume a kinematic model of the robot for example diff drive or omni directional etc. while generating motion plans for the robot. Can knowledge of the dynamics of the robot help ...
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### Determination of the operational space dynamic model (Task space)

I am trying to implement a hybrid Force/Motion controller for a quadruped. To do that I first need the Inverse Dynamic Model of the robot in Operational Space. I found a lot of resources on how to ...
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### 4 wheeled differential wheeled (skid-steer) robot steering problem

My question is about a square shaped differential wheeled robot, I built, that has a hub-motor (BLDC motor) attached to each corner, i.e., the wheels on the same side, either left or right, have the ...
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### Angular Velocities of CoM in Global Coordinate

The block diagram of the robot is shown as above. Here, $\phi$ is the angle between $X_v$ and $X_0$ (Yaw angle of the robot), and $\psi$ is the angle between $Z_b$ and $Z_v$ (pitch angle of the robot'...
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### Cannot get 3 DOF bicycle model to run correctly

I'm trying to simulate a vehicle using a dynamic bicycle model but I cannot seem to get it working. If I set a constant steering angle the lateral velocity grows exponentially and creates impossible ...
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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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### Understanding the kinetic energy expressions for a 1 link vs 2 link robot arm

I'm studying these lecture notes on dynamic models of robot arm links, slides 33-36, where two examples are given for the kinetic energies for a single link and two link robot arm. In the single ...
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### All Joint Angle values not converging to desired set point (I am using Roy Featherstone's Spatial Toolbox)

I need the robot joint angles to become the same as given (desired) joint angles. The kinematics and dynamics (used Spatial Toolbox) are correct and the motor models are realistic too. But out of 3 ...
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### Non-planar robot Dynamics error using Roy Featherstone's Spatial toolbox

I am using this code to test robot dynamics of above robot using Spatial Toolbox function: FDab(rob, [0;0;0], [0;0;0], [0;0;0]) %a_grav = [0,0,-9.81] But it ...
163 views

### Joint torque sensor vs end-effector force sensor

I am trying to understand the difference between joint torque sensors, and force sensors, in a robot arm. From what I understand, joint torque sensors estimate the torque at each joint, whereas a ...
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### 3-DOF Robot Dynamics error in Robotics Toolbox

I am trying to compute dynamics of 3 DOF robot using Robotics Toolbox by executing this code: robot.accel(q, zeros(1,3), zeros(1,3)) But I am getting this error: ...
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### Effiecient computation of coriollis matrix

I want to perform kinodynamic motion planning on a 6DoF hybrid manipulator. I calculated mass matrix, coriollis matrix etc using the lagrangian method. The coriollis matirx was calculated symbolically ...
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### Doing a project for college for a manned drone theortically only

Weight of the Drone in total will be 240 Kg. It Will be a quad copter drone setup but with 8 rotors(two on each corner) for redundancy purpose. Aim is achieve Thrust/weight ratio of 2. So need total ...
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### When and when not to use the Inertia tensor in Kinetic energy computing?

I'm trying to obtain the dynamic model of a 3D robot (academic problem), I have obtained the D-H table, the transformation matrix for each pair of links and the total transformation matrix. Now I'm ...
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### Two 4 bar mechanism vs stepper motor on each linkage in a 4 DOF robotic arm

I am planning to make a 4 Degree of Freedom(DOF) robotic arm. I have a confusion in mechanical design of the robot. Shall I use two 4 bar mechanisms to reduce the number of actuators? or a stepper ...
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### “modern contact dynamics” - Why are spring-damper contact models not being used anymore for dynamic simulations in robotics?

While researching different physics engines for dynamic simulations in robotics I found the following statement on the MoJoCo documentation website: Physics engines have traditionally separated in ...
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### 6DOF serial robot (PUMA robot) dynamic model equations

I'm trying to find the most simplified (though accurate) calculations for the dynamic model of a standard 6DOF serial robot (PUMA robot). I found this great paper: https://www-cs.stanford.edu/group/...
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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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### Dynamics of a robot manipulator with a force acting on the end-effector

I have this exercise The dynamic model is $B(q)\ddot{q}+S(q,\dot{q})\dot{q}=\tau+\tau_k$ Where $B(q)$ is the inertia matrix, $S(q,\dot{q})\dot{q}$ are the centrifugal and Coriolis terms, $\tau$ is ...
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### Dynamic model of two wheeled mobile robot

I wanted to design a LQR controller for my two wheel mobile robot. What are the equation of two wheeled mobile robot can be rearranged into state space model? My two wheeled mobile robot is nonlinear ...
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### Confusion about Jacobians stemming from class notes

So I thought I understood well enough what a Jacobian was (in the context of an $n$-DOF robot) -- a function that takes a vector of n joint positions and returns an $n \times n$ matrix that can be ...
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### robotic arm DOF

I'm working on an assignment and was wondering aobut the degrees of freedom this system has. The generalized coordinates are: $\underline{q}:$ \begin{bmatrix} x \\ \theta_{1} \\ \theta_{2} \\ \end{...
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### Quadrotor SE3 Controller: Calculating Rd_dot

I am trying to simulate and implement the controller in the paper Geometric Tracking Control of a Quadrotor UAV on SE(3). I have the dynamics implemented, however I am stuck at one part in the ...
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### How to interpret and apply results from Inverse Dynamics

I am applying Recursive Newton Euler Inverse Dynamics to a simple two link model. If I apply the result torques and forces using PhysX or Bullet Physics I get unexpected results. The model spins and ...
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I am trying to simulate and implement the controller of the paper Geometric Tracking Control of a Quadrotor UAV on SE(3). To do this I need to first implement the dynamics of the quadrotor. According ...