Tadej Petrič's research while affiliated with Jožef Stefan Institute and other places

Publications (9)

Chapter
To achieve higher positioning accuracy, it is common practice to calibrate the robot. An essential part of the calibration is the estimation of the kinematic parameters. Due to various nonlinear influences on the end-effector position accuracy, such as joint and link flexibility, standard methods of identifying kinematic parameters do not always gi...
Chapter
Collaborative robotics is one of the fastest developing but at the same time one of the most challenging fields in robotics. The reason for the latter is that a good robot collaborator should precisely understand the intentions of the human coworker. In this paper, human-robot collaboration is addressed by the application of a dynamical phase state...
Article
Full-text available
Purpose of Review The ability to autonomously manipulate the physical world is the key capability needed to fulfill the potential of cognitive robots. Humanoid robots, which offer very rich sensorimotor capabilities, have made giant leaps in their manipulation capabilities in recent years. Due to their similarity to humans, the progress can be part...
Conference Paper
Full-text available
Quasi-passive exoskeletons have emerged as a solution that avoids the high energy requirements that negatively affect the efficiency of exoskeletons. These exoskeletons do not deliver positive mechanical work to the joint, but accumulate and deliver energy in a viscoelastic element that is actively placed or removed parallel to the user's muscles....
Chapter
One of the major causes of disability and sick day leaves is lower back pain. Hence it can result in a decreased life quality and lower industrial productivity. One of the possible solutions to lower back pain could be the use of exoskeletons, which would reduce the spinal loading. One of such solutions is a quasi-passive spinal exoskeleton that en...
Chapter
Compliant robots with constant joint stiffness (Serial Elastic Actuators - SEA), on the contrary to ones with variable joint stiffness (Variable Stiffness Actuators – VSA), have limited capabilities for modulating robot mechanical impedance in the interaction task. However, in the case of kinematic redundancy in specific tasks, robots can exploit t...
Chapter
Several approaches exist for learning and control of robot behaviors in physical human-robot interaction (PHRI) scenarios. One of these is the approach based on virtual guides which actively helps to guide the user. Such a system enables guiding users towards preferred movement directions or prevents them to enter into a prohibited zone. Despite be...
Chapter
In this paper, we consider the problem of generating smooth Cartesian paths for robots passing through a sequence of waypoints. For interpolation between waypoints we propose to use radial basis functions (RBF). First, we describe RBF based on Gaussian kernel functions and how the weights are calculated. The path generation considers also boundary...
Article
Full-text available
Research and development of active and passive exoskeletons for preventing work related injuries has steadily increased in the last decade. Recently, new types of quasi-passive designs have been emerging. These exoskeletons use passive viscoelastic elements, such as springs and dampers, to provide support to the user, while using small actuators on...

Citations

... dedicated dual-arm setups have more degrees of freedom and more flexible end effectors. Dual arms have the advantage of being able to directly mimic human motions, either repetitive motions or human tele-operated motions (Kim et al., 1999;Kulić et al., 2012;Zuher and Romero, 2012;Gams et al., 2022;Zhou et al., 2022). In addition, dual arms can work together for large object manipulation Gams et al. (2015) (Figure 8C) and hand-to-hand manipulation Vahrenkamp et al. (2009). ...
... There are usually three approaches to changing stiffness in electromechanical VSAs. These include 1) Changing the spring preload [3,4], 2) Changing the transmission ratio between the compliant element and the load [5], and 3) Changing the physical properties of the elastic element [6][7][8]. One solution to reduce the weight and size of actuators in exoskeletons and prostheses is to use quasi-passive mechanisms, as it has been shown that negative limb work can be accumulated and reused in the elastic element to reduce the metabolic cost of walking [9], running [10], or jumping. ...
... Thus, a suitable parametrization method is needed to approximate the path. As a suitable solution, the radial basis functions (RBF) based on Gaussian kernel functions are selected [34]. The RBF-coded trajectory allowed adjustment of the movement speed. ...
... The experiment emulated a typical assembly task where the interaction force was generated by the interaction between an object in the gripper and the environment. The parameters of the robot platform can be found in [30]. All values for joint stiffness were set to 400 Nm/rad. ...
... Passive mechanisms serve to minimize the size, weight, and necessary active torque, which in turn improves portability (Smith et al., 2013;Blanchet et al., 2020;Miakovic et al., 2022). Recently, the semi-active, semi-passive, and quasi-passive nature of this combined transmission system has been conceptually investigated on lower limbs (Lambrecht and Kazerooni, 2009;Hassan and Sadik, 2018;Di Natali et al., 2020;Pillai et al., 2020;Al-Hayali et al., 2021aRen et al., 2021;Wang et al., 2021), upper limbs (Naito et al., 2007;Smith et al., 2013;Zahedi et al., 2021;Bai et al., 2022;Winter et al., 2022), and spines (Jamsek et al., 2020). However, from a practical point of view, it is necessary to consider the HRI, as well as control delays in regulating the active component of this integrated system. ...