In this paper, we propose a simplified variable admittance controller applied to robot joint control. It is based on a virtual agonist-antagonist mechanism (VAAM) consisting of contractile and parallel elements (CEs and PEs). ”Virtual” here means that every joint physically actuated by a standard servo motor can produce variably compliant motions as if it were driven by a pair of agonist and an...

The paper addresses the problem of controlling the joints of an flexible joint robot with a state feedback controller and proposes a gradual way of extending such a controller towards feedback linearization. The global asymptotic stability for the state feedback controller with gravity compensation is proven. Experimental results on the DLR light-weight robots validate the method.

This paper develops an automatic parking algorithm based on a fuzzy logic controller with the vehicle pose for the input and the steering angle for the output. In this way some feasible reference trajectory path have been introduced according to geometric and kinematic constraints and nonholonomic constraints to simulate motion path of car. Also a novel method is used for parking space detec...

This letter presents a passivity-based inverse dynamics (ID) controller using global energy tank. The proposed control approach allows us to achieve safe multi-contact scenario on torque controlled humanoid robot. is primarily task space ID quadratic programming (QP) which efficiently computes the reference satisfying non-hierarchical set of tasks. Our work extends this by adding tank modulatin...

Fuzzy log& can be used advantageously in autonomous orbital operations that require the capability of handling imprecise measurements from sensors. Several applications are under way at the Software Technology Laboratory, NASA / Johnson Space Center to investigate fuzzy logic approaches and develop guidance and control algorithms for autonomous orbital operations. Translational as well as rotat...

Joint friction is a major problem in accurately controlling manipulators performing small precise tasks. Previously developed solutions to this problem require the use of either complex and unreliable models of the joint friction or expensive and delicate internal joint torque sensors. Here a simple, cost-effective method for compensating the effect of joint friction is proposed. It uses a six-...

This article presents the implementation of a new algorithm of force guided motions with a six axis articulated robot frequently used in research laboratories. This new approach is based on the idea of impedance control in joint space and it is implemented on a digital signal processor-based robot controller. It allows an intuitive force guidance of the robot by taking the gripper by the hand. ...

A Cartesian compliance based control scheme is presented for the kinematically redundant serial manipulator. The controller can be decomposed into three parts. The first part imposes the desired cartesian compliance of the end effector. The second part attempts to shape the cartesian compliance parameters of the virtual points by the avaiable joint torque null space. Finally, the additional ter...

We developed a robust control policy design method in high-dimensional state space by using differential dynamic programming with a minimax criterion. As an example, we applied our method to a simulated five link biped robot. The results show lower joint torques from the optimal control policy compared to a hand-tuned PD servo controller. Results also show that the simulated biped robot can suc...