Accurate force control and co-manipulation control using hybrid external command

Impedance Control Using a Cascaded Loop Force Control

“…The previous study [14], a simple control law was studied for the force control using an IP correction for the velocity loop and a P correction for the force loop. Then, this control law was adapted in order to perform the co-manipulation task.…”

“…The apparent impedance of the control law is a mass-damper system where the mass depends on the parameters of the PI inner velocity controller and the damper depends of the P outer force controller. This control law has been defined in a previous study [14] and applied on a known system with one dof ( [15], [16], [17]).…”

“…The main contribution of this paper is to compare this control law to a classical impedance controller ( [18]). The aim is to create an equivalence between the two control laws, allowing us to tune the first one [14] according to a desired impedance and tune the second one [18] according to the desired performance of the first control law. This equivalence, will allows the utilisation of the classical tool of automatism in the case of robot interacting with the environment.…”

On the Use of Inner Position Loop in Co-manipulation Task

“…Body 2 represents the other extremity of the force sensor and the tool, which is in contact with the environment. For each body i = [1,2], M i is the mass in translation (kg), F vi is the viscous friction coefficient (N/(m/s)) and F ci is the Coulomb friction (N ). For position q i , the velocities (m/s) and the accelerations (m/s 2 ) are respectively calledq i andq i .…”

“…Here, the configuration of the robot leads us to consider an outer force loop which encapsulates an inner velocity loop as presented in [2]. The main advantages of this control law are its simplicity and the fact it can be easily tuned into an equivalent impedance control law [1].…”