Risk estimation for intervertebral disc pressure through musculoskeletal joint reaction force simulation

Abstract

This research proposes a novel method that evaluates joint reaction forces by motion analysis using a musculoskeletal model. While general muscle tension estimations minimize the sum of the muscle tensions, the proposed method utilizes the joint reaction forces themselves in the objective function of the optimization problem in addition to conventional method. This method can estimate a pattern of the muscle tensions that maximizes or minimizes a specific joint force. As a typical outcome, the proposed method allows evaluating intervertebral disc compressive force caused by co-contraction of muscles while avoiding risk underestimation. We analyzed the actual lifting motion as an example and confirmed that the method can estimate the muscle tension distribution under different tension conditions.

Real-time musculoskeletal visualization of muscle tension and joint reaction forces

“…1) Receive data from sensor and extract useful information; 2) Perform an inverse kinematics (IK) of a musculoskeletal model to compute joint angles [11]; 3) Compute the derivatives of the joint angles; 4) Compute the muscle tensions, joint torques and joint reaction forces through inverse dynamics computation (ID) of the musculoskeletal model [7]; 5) Output the model visualization into DhaibaWorks; 6) If asked by the user, plot data in real-time; 7) If asked by the user, record the data in a csv or binary file. In step 1), The software gets as input either motion capture markers from Cortex 1 system or XSens IMU sensors 2 .…”

“…with where f ∈ R Nw is the wire tension, τ j ∈ R Ndof is the joint torques, τ c ∈ R Nc is the joint reaction forces, J j ∈ R Nw×Ndof is the Jacobian matrix that maps the joint torques to the wire tension, J c ∈ R Nw×Nc is the Jacobian matrix that maps the joint reaction forces to the wire tension, and W f , W j and W c are weighting matrix. The algorithm itself has been proved viable in [7];…”

“…It is because the joint reaction forces are generated by the co-contraction of muscles rather than the external or gravitational burdens [6]. Though the off-line analysis approaches based on musculoskeletal simulation has been developed [7], the real-time estimation of joint reaction forces as well as muscle forces is therefore an important issue when monitoring the risk of physical health problems. Also intrusive methods exist [8], it is difficult to be applied in factory.…”

Musculoskeletal Estimation Using Inertial Measurement Units and Single Video Image

“…The former goes with estimations (and thus imprecision), and with some time constraints since all the computations need to be done in a short amount of time. Although several off-line estimations exist [5] [6], the focus will be made on on-line computation while reducing cumbersomeness.…”

“…In our previous work [6], we developed a framework of visualizing the physical burden of human body during movements by using the human musculoskeletal model [7]. The system can realize the real-time estimation of the several information like joint angles, joint torques, muscle tensions, and joint reaction forces [5]. The main objective is to support factory workers by monitoring the risk of physical health problems like low back pains.…”