Point contacts#
Fixed point contact#
To be used with: position task
This type of contact can be used for points that are attached to the world.
# Creating a leg task
leg_task = robot.add_position_task("leg1")
# Creating a fixed point contact
# Warning: this is NOT an unilateral contact, it can pull on the ground
leg_contact = robot.add_fixed_point_contact(leg_task)
Hanging quadruped
In this example, a quadruped robot is attached with four points (which are not unilateral). All motors expect one are unactuated (torque is set to zero). This results in a “hanging” robot.
Point (unilateral) contact#
To be used with: position task
# Creating a leg task
leg_task = robot.add_position_task("leg1")
# Creating an unilateral point contact
leg_contact = robot.add_point_contact(leg_task)
# If needed, the normal to the surface in the world can be set
leg_contact.R_world_surface = np.eye(3)
# You can adjust the friction coefficient by setting mu
leg_contact.mu = 0.5
Quadruped
A quadruped robot is on the floor with 4 unilateral contact points.