Towards Safe Speed and Separation Monitoring in Human-Robot Collaboration with 3D-Time-of-Flight Cameras

Himmelsbach, Urban B.; Wendt, Thomas M.; Lai, Matthias

doi:10.1109/irc.2018.00042

Cited by 12 publications

(7 citation statements)

References 8 publications

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“…The synchronization interval was set to 1 s. When the synchronized state was achieved, the trigger's position of the synchronizing camera is recorded using an oscilloscope. The necessary buffer is calculated using (2). With t overlap = 0.08 ms from the first…”

Section: Measurements and Resultsmentioning

confidence: 99%

Interference Avoidance for Two Time-of-Flight Cameras Using Autonomous Optical Synchronization

Wermke

Wubbenhorst

Meffert

2020

2020 6th International Conference on Control, Automation and Robotics (ICCAR)

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Time-of-Flight (ToF) cameras acquire 3-D images where each pixel relates to the distance in the observed scene. These images are acquired by emitting modulated light and measuring the phase of its reflection from an object. Improvements in ToF camera technology make it a promising alternative to current 3-D imaging sensors despite possessing comparatively lower resolution. Overcoming lower resolution, of single ToF camera images, is achieved using a multi-camera setup. However, the simultaneous operation of multiple ToF cameras causes interference resulting in erroneous depth measurements. An option to mitigate interference is the arrangement of multiple cameras in a consecutive order sharing the same frequency in assigned time slots, such that each camera illuminates the scene exclusively, a procedure known as time division multiple access (TDMA). The assignment of acquisition times is usually performed by a master synchronizing device implementing a time synchronization protocol that requires an additional communication channel. This paper presents a different approach requiring no additional infrastructure to utilize TDMA by adding a synchronization software procedure to the camera's microprocessor which effectively enables a camera to sense the acquisition process of other cameras and rapidly synchronize itself autonomously to operate without interference. Experimental results with two ToF cameras provide substantive evidence of the efficacy of this approach. The operation of the standalone cameras achieved the desired synchronization without illumination interference. The proposed synchronization procedure takes advantages of the zero interference of TDMA and overcomes traditional hard-wired synchronization setups, offering an autonomous and potentially mobile operation of ToF camera deployment.

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Section: Measurements and Resultsmentioning

confidence: 99%

Interference Avoidance for Two Time-of-Flight Cameras Using Autonomous Optical Synchronization

Wermke

Wubbenhorst

Meffert

2020

2020 6th International Conference on Control, Automation and Robotics (ICCAR)

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“…In this appendix, first, the stability of the tracking error defined in (3) is investigated under the design of (4). Taking the time derivative of (3) and then substituting (4) yields ė = Vd − Ĵ Ĵ * ( Vd + K p ē) (12) and utilizing (5a) results in…”

Section: Appendix Amentioning

confidence: 99%

Toward safe and high-performance human–robot collaboration via implementation of redundancy and understanding the effects of admittance term parameters

et al. 2021

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Summary Today, demandsin industrial manufacturing mandate humans to work with large-scale industrial robots, and this collaboration may result in dangerous conditions for humans. To deal with this situation, this work proposes a novel approach for redundant large-scale industrial robots. In the proposed approach, an admittance controller is designed to regulate the interaction between the end effector of the robot and the human. Additionally, an obstacle avoidance algorithm is implemented in the null space of the robot to prevent any possible unexpected collision between the human and the links of the robot. After safety performance of this approach is verified via simulations and experimental studies, the effect of the parameters of the admittance controller on the performance of collaboration in terms of both accuracy and total human effort is investigated. This investigation is carried out via 8 experiments by the participation of 10 test subjects in which the effect of different admittance controller parameters such as mass and damper are compared. As a result of this investigation, tuning insights for such parameters are revealed.

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“…There is an increasing demand for high-resolution remote sensing systems across different parts of the wavelength spectrum. The Time-of-Flight (ToF) camera is one such remote sensing system for macroscopic scene detection that has gained popularity in the recent years and is being used in a wide range of applications such as vehicle monitoring and obstacle detection in the automotive industry, safe patient monitoring for healthcare, 3D scanning, and human-machine interactions [1], [2], [3]. Specifically, the amplitude-modulated continuous wave (AMCW) ToF cameras have had a wide commercial impact due to their small size and high signalto-noise (SNR) ratio [4].…”

Section: Introductionmentioning

confidence: 99%

A Novel Approach for Solving MPI for Multi-Target ToF Imaging Using Subdivision-Based Nested Compressed Sensing

Guha,

Ahmed,

Conde

2023

2023 31st European Signal Processing Conference (EUSIPCO)

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Time-of-Flight (ToF) cameras have become a popular imaging modality for macroscopic scene detection. In particular, amplitude-modulated continuous wave (AMCW) ToF cameras use the phase difference between sent and received signals for object depth reconstruction. However, various sources of multipath reflections exist in practice, causing each ToF pixel to erroneously receive a superposition of multiple reflections instead of a single bounce. This leads to distortions in the phase difference and consequently, errors in the depth maps. Compressed Sensing methods have emerged as an effective approach to solve this multipath interference (MPI) problem. However, it has two major disadvantages-large sensing matrix size leading to high computational load, and a high mutual coherence causing reconstruction failure. This paper introduces a subdivision-based nested compressed sensing algorithm that aims to alleviate these known disadvantages. Measurements at multiple modulation frequencies are used to isolate the k interfering signals in the time domain. Simulation results are presented with a noise performance analysis and results based on real multitarget measurement data are also discussed.Index Terms-time-of-flight, multi-path interference, depth resolution improvement, compressed sensing This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodoska-Curie grant agreement No 860370.

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Towards Safe Speed and Separation Monitoring in Human-Robot Collaboration with 3D-Time-of-Flight Cameras

Cited by 12 publications

References 8 publications

Interference Avoidance for Two Time-of-Flight Cameras Using Autonomous Optical Synchronization

Interference Avoidance for Two Time-of-Flight Cameras Using Autonomous Optical Synchronization

Toward safe and high-performance human–robot collaboration via implementation of redundancy and understanding the effects of admittance term parameters

A Novel Approach for Solving MPI for Multi-Target ToF Imaging Using Subdivision-Based Nested Compressed Sensing

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