This article reports recent experiments with a new class of model-base
d adaptive force control algorithms for robot arms [6, 3]. The problem
addressed in this article is the control of robots whose motion is co
nstrained by point contact between the robot tool and a smooth rigid e
nvironment or workpiece. Manufacturing applications for force control
include a great variety of commonplace tasks, such as grinding, polish
ing, buffing, deburring, and assembly operations currently performed e
ither manually or by fixed automation equipment. The new force control
algorithm provides asymptotically exact tracking of both end-effector
position and contact-force [6]. This force control algorithm utilizes
a sliding-mode control technique of a type first espoused for the cas
e of free (non-contact) robot motion [21]. The stability of the new fo
rce control algorithm can be proven with respect to the commonly accep
ted nonlinear rigid body dynamical equations of motion. Moreover, its
adaptive extension can be shown to adaptively compensate for unknown p
lant parameters such as link and payload inertia, joint friction, and
friction arising at the contact point between the tool tip and the sur
face. In [15,5] the authors report satisfactory performance of this fo
rce control algorithm in numerical simulation studies. This article de
monstrates the comparative advantages and disadvantages of this contro
l algorithm under a variety of conditions in actual working implementa
tions.