New video on the Straight walk gait
This video shows some important improvements with respect to Video 2: no more fast movements of the torso during heel strike and smoother transitions from one phase to another.
Some comments:
1: Because the commands are hardcoded there are some back and forth movements of the torso in Sagittal plan at heel strike. This problem will be solved when the controller will be connected to sensors on the feet (the Murata rotary encoder connected with the heel).
2: After heel strike the leg behind (pushing leg) tightens and in the same time the robot lateralizes – like this first we stabilize the robot and second a smooth transition towards a completion of the lateralization to prepare the swing phase.
3: An active participation of the torso during the lateralization in the frontal and horizontal planes which is interesting. These movements clearly help (and my guess is that they are needed when the stride length increases) and provide a more natural walking.
Consideration on the Turning gait
The second video shows a rotation, I use the same algorithm and I (just) needed to modify the parameters and understand how to tune the angles in order to create a generic turning gait.
Obviously, the main parameter to consider is the angle of rotation of the foot (actually the hip) and let see what are the consequences on the whole gait.
If the foot angle is around 20/30 degrees, it is possible to extend the swing leg and rotate the pelvic as well. The gait played in the video falls in this case.
However if the angle is large, like 40 degrees or more, the swing leg will not really extend – due mainly to mechanical constraints – otherwise it will be quite difficult to generate the movements for the swing leg to become the stance leg afterwards.
Another challenge is the rotation of the Pelvic (or the external rotation of the stance leg – which becomes the swing leg) in the horizontal plane. The larger the hip angle of the swing leg (which then becomes the stance leg), the larger is the rotation of the stance leg (which becomes the swing leg).
I am working on a gait addressing a large angle in order to see how it works.
The picture below is a graphical representation of the different cases.
Here is the video: