The gait generator

Ike Mulder

Today it’s time for an update of the Software & Control Department again. We made a lot of progress in the meantime and we would like to tell you more about this in this blog!

Last time we talked about the different commands we can send to the motor, this week we will show where these commands come from. 

They are generated in the gait generator. This is a kind of app, which we can use separately from the exoskeleton to design different gait patterns. He is able to save the generated joint angles, that can be uploaded to the exoskeleton subsequently, so that it can execute these angles. 

The gait generator starts with the graphic user interface (GUI), in which the user (the one that programs the gait pattern) can choose which parameters he would like to use to design the desired gait pattern. He or she can for example choose the angle the knee will make or the x-position of the foot. In this way, different separate points can be chosen, which the gait pattern has to follow; in this way you can say, for example, that when the step is completed for 80% the knee should make an angle of 60 degrees. These points are what we call the key-events. 

These key-events go into the spline generator after that. This spline generator will interpolate between all chosen separate point, so that a continue gait pattern is generated; these are the so-called splines. These splines will go to the kinematics block afterwards, together with some specific parameters of our pilot, such as the length of his upper leg and lower leg. In the kinematics block the other two required parameters are being calculated, with the help of the parameters that were chosen beforehand. In our case these two other parameters are the angle the hip should make and the y-position of the foot.

Now the gait pattern is finished and it is saved and judged by the gait checker. Beforehand specific wishes/requirements for the gait pattern are determined, such as the maximum velocity of the joints and the step length, and by means of the gait checker it is checked if the gait pattern meets all these requirements. So, the pattern receives a kind of mark. Subsequently, the generated gait pattern is sent back to the graphic user interface so that the user can see what kind of gait pattern he or she created. This finished the design loop.

All different steps are shown in the image.