scholarly journals Task Space Planning With Complementarity Constraint-Based Obstacle Avoidance

2021 ◽  
Author(s):  
Anirban Sinha ◽  
Anik Sarker ◽  
Nilanjan Chakraborty
Keyword(s):  
Collision Avoidance ◽  
Linear Interpolation ◽  
Task Space ◽  
Local Motion ◽  
Task Constraints ◽  
Space Planning ◽  
Complementarity Constraint ◽  
State Evolution ◽  
Present Simulation ◽  
And Task

Abstract In this paper, we present a task space-based local motion planner that incorporates collision avoidance and constraints on end-effector motion during the execution of a task. Our key technical contribution is the development of a novel kinematic state evolution model of the robot where the collision avoidance is encoded as a complementarity constraint. We show that the kinematic state evolution with collision avoidance can be represented as a Linear Complementarity Problem (LCP). Using the LCP model along with Screw Linear Interpolation (ScLERP) in SE(3), we show that it may be possible to compute a path between two given task space poses by directly moving from the start to the goal pose, even if there are potential collisions with obstacles. Scalability of the planner is demonstrated with experiments using a physical robot. We present simulation and experimental results with both collision avoidance and task constraints to show the efficacy of our approach.

Point-to-Point Path Planning Based on User Guidance and Screw Linear Interpolation

2021 ◽  
Author(s):  
Riddhiman Laha ◽  
Anjali Rao ◽  
Luis F. C. Figueredo ◽  
Qing Chang ◽  
Sami Haddadin ◽  
...  
Keyword(s):  
Linear Interpolation ◽  
Industrial Robots ◽  
Geometric Constraints ◽  
Task Space ◽  
Motion Generation ◽  
Task Constraints ◽  
Single User ◽  
Point To Point ◽  
Definition Of ◽  
Time Point

Abstract Despite the increasing number of collaborative robots in human-centered manufacturing, currently, industrial robots are still largely preprogrammed with very little autonomous features. In this context, it is paramount that the robot planning and motion generation strategies are able to account for changes in production line in a timely and easy-to-implement fashion. The same requirements are also valid for service robotics in unstructured environments where an explicit definition of a task and the underlying path and constraints are often hard to characterize. In this regard, this paper presents a real-time point-to-point kinematic task-space planner based on screw interpolation that implicitly follows the underlying geometric constraints from a user demonstration. We demonstrate through example scenarios that implicit task constraints in a single user demonstration can be captured in our approach. It is important to highlight that the proposed planner does not learn a trajectory or intends to imitate a human trajectory, but rather explores the geometric features throughout a one-time guidance and extend such features as constraints in a generalized path generator. In this sense, the framework allows for generalization of initial and final configurations, it accommodates path disturbances, and it is agnostic to the robot being used. We evaluate our approach on the 7 DOF Baxter robot on a multitude of common tasks and also show generalization ability of our method with respect to different conditions.

scholarly journals No-go trials in task switching: effects on the task-set and task-space level

2021 ◽  
Author(s):  
Juliane Scheil ◽  
Thomas Kleinsorge
Keyword(s):  
Task Switching ◽  
The Other ◽  
Specific Task ◽  
Task Space ◽  
Response Level ◽  
Task Set ◽  
Common Marker ◽  
Task Sets ◽  
And Task

AbstractA common marker for inhibition processes in task switching are n − 2 repetition costs. The present study aimed at elucidating effects of no-go trials on n − 2 repetition costs. In contrast to the previous studies, no-go trials were associated with only one of the three tasks in the present two experiments. High n − 2 repetition costs occurred if the no-go task had to be executed in trial n − 2, irrespective of whether a response had to be withheld or not. In contrast, no n − 2 repetition costs were visible if the other two tasks were relevant in n − 2. Whereas this n − 2 effect was unaffected by whether participants could reliably exclude a no-go trial or not, effects of no-gos in trial n were determined by this knowledge. The results differ from effects of no-go trials that are not bound to a specific task. It is assumed that the present no-go variation exerted its effect not on the response level, but on the level of task sets, resulting in enhanced salience of the no-go task that leads to higher activation and, as a consequence, to stronger inhibition. The dissociation of the effects on no-gos in trials n − 2 and n as a function of foreknowledge suggests that the balance between activation and inhibition is shifted not only for single trials and tasks, but for the whole task space.

scholarly journals On the choice of grasp type and location when handing over an object

2019 ◽  
Vol 4 (27) ◽  
pp. eaau9757 ◽  
Author(s):  
F. Cini ◽  
V. Ortenzi ◽  
P. Corke ◽  
M. Controzzi
Keyword(s):  
Human Hand ◽  
Social Activities ◽  
Robotic Grasping ◽  
Task Constraints ◽  
Cooperative Manipulation ◽  
Open Issue ◽  
Grasp Type ◽  
And Task

The human hand is capable of performing countless grasps and gestures that are the basis for social activities. However, which grasps contribute the most to the manipulation skills needed during collaborative tasks, and thus which grasps should be included in a robot companion, is still an open issue. Here, we investigated grasp choice and hand placement on objects during a handover when subsequent tasks are performed by the receiver and when in-hand and bimanual manipulation are not allowed. Our findings suggest that, in this scenario, human passers favor precision grasps during such handovers. Passers also tend to grasp the purposive part of objects and leave “handles” unobstructed to the receivers. Intuitively, this choice allows receivers to comfortably perform subsequent tasks with the objects. In practice, many factors contribute to a choice of grasp, e.g., object and task constraints. However, not all of these factors have had enough emphasis in the implementation of grasping by robots, particularly the constraints introduced by a task, which are critical to the success of a handover. Successful robotic grasping is important if robots are to help humans with tasks. We believe that the results of this work can benefit the wider robotics community, with applications ranging from industrial cooperative manipulation to household collaborative manipulation.

scholarly journals Target Finding With a Spatially Aware Handheld Chart Display

2012 ◽  
Vol 54 (6) ◽  
pp. 1040-1052 ◽  
Author(s):  
Colin Ware ◽  
Roland Arsenault
Keyword(s):  
Cognitive Strategies ◽  
External World ◽  
Perspective View ◽  
Task Constraints ◽  
Spatial Transformations ◽  
Handheld Device ◽  
Environmental Features ◽  
Display Configuration ◽  
Small Screen Devices ◽  
And Task

Objective: The objective was to evaluate the use of a spatially aware handheld chart display in a comparison with a track-up fixed display configuration and to investigate how cognitive strategies vary when performing the task of matching chart symbols with environmental features under different display geometries and task constraints. Background: Small-screen devices containing both accelerometers and magnetometers support the development of spatially aware handheld maps. These can be designed so that symbols representing targets in the external world appear in a perspective view determined by the orientation of the device. Method: A panoramic display was used to simulate a marine environment. The task involved matching targets in the scene to symbols on simulated chart displays. In Experiment 1, a spatially aware handheld chart display was compared to a fixed track-up chart display. In Experiment 2, a gaze monitoring system was added and the distance between the chart display and the scene viewpoint was varied. Results: All respondents were faster with the handheld device. Novices were much more accurate with the handheld device. People allocated their gaze very differently if they had to move between a map display and a view of the environment. Conclusion: There may be important benefits to spatially aware handheld displays in reducing errors relating to common navigation tasks. Application: Both the difficulty of spatial transformations and the allocation of attention should be considered in the design of chart displays.

Environmental and task constraints influence footfall variability in track and field jumping events

2017 ◽  
Vol 13 (4) ◽  
pp. 552-558
Author(s):  
Hubert Makaruk ◽  
Jared Marak Porter ◽  
Marcin Starzak
Keyword(s):  
Step Length ◽  
Gait Pattern ◽  
Track And Field ◽  
Environmental Constraints ◽  
Male Athletes ◽  
Task Constraints ◽  
Long Jump ◽  
Pointing Control ◽  
Pole Vault ◽  
And Task

By analysis of footfall variability in the long jump, triple jump, and pole vault, the present study was designed to highlight gait variability patterns required in varied nested tasks. Twelve male athletes in each event who participated in one international and two national competitions were involved in this study. Twenty five pairs of 1-m Optojump Next system bars were used to evaluate relevant footfall placement. The footfall variability was taken to present the pattern of step regulation and onset of visual regulation. The main results of this study showed that pole vaulters manifested a highly consistent gait pattern, which was different than the pattern which appeared in the horizontal jumps. The results also revealed that the onset of step length adjustments in the horizontal jumps occurred significantly later during the zeroing-in phase of the approach run in comparison to those utilized by the pole vaulters. These findings indicate that locomotor pointing control in the long jump, triple jump, and pole vault produce specific footfall variability patterns due to different task and environmental constraints that need to be taken into account during training and competition settings.

scholarly journals Rat anterior cingulate cortex recalls features of remote reward locations after disfavoured reinforcements

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Ali Mashhoori ◽  
Saeedeh Hashemnia ◽  
Bruce L McNaughton ◽  
David R Euston ◽  
Aaron J Gruber
Keyword(s):  
Anterior Cingulate Cortex ◽  
Cognitive Processes ◽  
Cingulate Cortex ◽  
Anterior Cingulate ◽  
Task Space ◽  
Spatiotemporal Resolution ◽  
Related Information ◽  
Current State ◽  
Multimodal Information ◽  
And Task

The anterior cingulate cortex (ACC) encodes information supporting mnemonic and cognitive processes. We show here that a rat’s position can be decoded with high spatiotemporal resolution from ACC activity. ACC neurons encoded the current state of the animal and task, except for brief excursions that sometimes occurred at target feeders. During excursions, the decoded position became more similar to a remote target feeder than the rat’s physical position. Excursions recruited activation of neurons encoding choice and reward, and the likelihood of excursions at a feeder was inversely correlated with feeder preference. These data suggest that the excursion phenomenon was related to evaluating real or fictive choice outcomes, particularly after disfavoured reinforcements. We propose that the multiplexing of position with choice-related information forms a mental model isomorphic with the task space, which can be mentally navigated via excursions to recall multimodal information about the utility of remote locations.

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