Questions about StandingExo

Hi

I would like to ask how the InitialConditions are set in StandingExo. After I run Main.Study.InitialConditions, the human body will become a squat position. If I want to change the initial position? Where should I modify?

And when i running the inverse dynamics analysis, the human model goes from squatting to standing. But I didn't find the driver that drives the movement. For example, the FitnessMachine.any has MachineOperation.any in the tutorial. Can you explain how this movement is performed?And Is there exoskeleton movement first, and then drives people's movement through AnyGeneralForce? Thank you in advance.

Best regards
Sam

Hi Sam,

the initial positions can be changed in the mannequin.any file. This is a file which is always used for setting pelvis global position and joint angles at load time.
Often the same angle values are used as drivers values in the model but this is not always the case that depends on the drivers and constraints in the model.

The HumanModel drives the exo in this model so the exo can be remove and the human will stil move.

The motion is defined in several files, but starts in JointsAndDrivers.any this file links to the other files which each helps defined the motion.

So e.g. TrunkNeckDrivers.any drives CoM position of the body ..

Best regards
Søren

Hi Søren

Thank you for your reply. I only see "TrunkDrivers.any", "RightArmDrivers.any" and "LeftArmDrivers.any" in JointsAndDrivers.any. I don't see the driver that defines lower limb drive, so what drives the model to stand up.

And no matter how I modify the mannequin.any, although the model position will change, but as long as I run the InitialCondition, the model will change to the squat position. I would like to ask what defines the InitialCondition and how I modify it?

I also want to ask whether Fitness Machine drives the model movement in FitnessMachine.any. Thank you in advance.

Best regards
Sam

Hi Sam,

By driving the height of the CoM of the human model the legs can be driven indirectly, it is not always that the human joints are driven directly.
In this model the CoM height is controlled in the file TrunkNeckDrivers.any using an interpolation driver called "Pelvis_PosY_Driver"

This driver points to the mannequin.any file to see the values, see the vector called "PelvisPosY_Vec" and "PelvisPosY_Time"

The fitness machine works the "other" way here the wheel is driven by a driver and the human follows along by constraining hands and feets to it.

Best regards
Søren

Hi Søren,

Thank you very much for your reply. I also want to ask a question about why there is Human_Ground_Connection in "AdditionalConstraints.any", why not connect directly to the exoskeleton but to the ground.

And AnyKinLinear lin is a kinematic measure. In Human_Ground_Connection, why does it use AnyKinLinear lin for connection? What is the difference between AnyKinLinear lin and joints?

This model is HumanModel driven the exo. I saw AnyGeneralForce6DOF in the Robot_Human_Interactions and the strength_Fy = 0. I want to ask how the effect of exoskeleton on HumanModel is calculated. Thank you again

Best regards
Sam

Hi Sam,

In this model the exo can be excluded and the model will still run, it would not do this if it was the other way around. I think this model was originally created without exo.The constraints in additionalconstraints.any file is just kinematics they do not transmit force, note that the Reaction.Type is set to off.
Note that in AnyBody you can have separation bewteen force and motion.
In principle the model could have been made the other way that the exo would drive the human kinematically, but the result will be the same.

AnyKinLinear is a measure that is correct, a joint is created using measures and adding constraints to these measures, so joints will always have linear and rotational measures built into them, these can be seen in the ModelTree if you browse a joint.

In the file AdditionalInteractions.any there is a number of "contact elements" defined between the exo and the human. These elements do not create motion constraints just forces.

See this link to more details on this "element "

By adding constraints to kinematic measures you can create "custom joints"

Best regards
Søren

Hi Søren,

Thank you very much for your reply. This model is HumanModel driven the exo. Is the exo driven by human through the contact elements?So how do we calculate the force that EXO has on people?
Thank you in advance.

Best regards
Sam

Hi Sam,

The Exo is driven kinematically by having kinematic constraints to the human model, these constraints do not transmit any force since Reation.Type={Off}; These constraints makes the exo follow the human.

The "contact elements " transmits the loads between exo and human, they do not create kinematics only force.

In this model torque is applied to the exo, the force is transmittedto the human by the "contact elements"

So when exo torque is adjusted, the exo needs different contact forces to be in balance, and these forces will also help the human.

Let me know if it make sense.

Best regards
Søren

Hi Søren,

Thank you very much for your help, it helped me a lot.

Best regards
Sam

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