What are the directions and magnitudes of joint reaction forces (both horizontal and vertical) and moments of the KNEE (running)?
Data you will need are:
Mass of participant: 67.2 kg Running direction: anterior
Joint: Knee
Segment: Lower Leg
Knee coordinates (m) y: 4.207, z: 1.313
COM coordinates (m) y: 4.235, z: 1.141
knee acceleration (m/s^2) y: 1.762, z: -3.738
COM acceleration (m/s^2) y: 0.511, z: -5.293
COM: Angular velocity (rad/s) = -19.997. Angular acceleration (rad/s^2) = -0.806.
COM: Linear acceleration (m/s^2) y: 0.511, z: -5.293
1. MUST draw free body diagram of tibia segment.
2. List all steps in detail of how to conduct inverse dynamics.
To determine the directions and magnitudes of joint reaction forces (both horizontal and vertical) and moments of the knee during running, you can follow these steps:
1. Start by drawing a free body diagram of the tibia segment. Identify all the forces acting on the tibia, including the forces applied by the surrounding muscles and tendons, as well as the joint reaction forces at the knee.
2. Conduct inverse dynamics to calculate the joint forces and moments. Inverse dynamics is a method used to determine the forces and moments acting at a joint based on motion capture data and segmental accelerations.
The steps to conduct inverse dynamics are as follows:
a. Calculate the linear acceleration of the center of mass (COM) using the given values for COM acceleration (y and z components).
b. Calculate the linear velocity and position of the COM using the linear acceleration and initial conditions.
c. Calculate the angular acceleration of the COM using the given angular acceleration value.
d. Calculate the angular velocity and position of the COM using the angular acceleration and initial conditions.
e. Calculate the distance between the joint and the COM in the y and z directions using the given coordinates for the knee and COM.
f. Calculate the accelerations of the joint in the y and z directions by adding the linear and angular accelerations of the COM.
g. Multiply the mass of the participant by the joint acceleration in each direction to obtain the joint force components.
h. The joint reaction forces in the horizontal and vertical directions are the x and z components of the joint force, respectively.
i. To find the moment about the joint, use the distance between the joint and the COM in the z direction and multiply it by the joint reaction force in the x direction.
By following these steps, you should be able to calculate the directions and magnitudes of the joint reaction forces (both horizontal and vertical) and moments at the knee during running.