Performance Analysis of the PMD Camboard Picoflexx Time-of-Flight Camera for Markerless Motion Capture Applications

The PMD Camboard Picoflexx Time-of-Flight (ToF) camera is evaluated against the Microsoft Kinect V2 to assess its performance in the context of markerless motion capture system for human body kinematics measurements. Various error sources such as the warm-up time, the depth distortion, the amplitude related error, the signal-to-noise ratio, and limitations such as their dependence on the illumination pattern and on the target distance, are studied and compared. The Picoflexx device is also compared to the Kinect V2 in relation to the quality of shape reconstructions, to assess its adequateness in modeling human body segments, and human body kinematics measurements. The final result of this paper is definitely useful to the research community, demonstrating that, even if the Picoflexx performs lower than the Kinect concerning the measurement performances, its behavior in estimating the volume of the body segments, the angles at the joints for human body kinematics, and the angle at the ankle in assisted walking applications is definitely satisfactory. These results are extremely significant to obtain accurate estimates of the parameters of the human body models in markerless motion capture applications, especially in laboratory-free environments, where compactness, lightweight, wireless connection, and low-power consumption are of outmost importance.

I. Introduction

Due to recent advances in medicine, life expectancy has dramatically increased and the number of elderly people (aged 60 and above) is expected to rise at a rate of 3% per year [1]. This demographic change has its inherent obstacles and poses a challenge on our society as more high-quality long-term care facilities and 50%–150% more geriatric nurses are needed in the coming future [2]. In addition to this, geriatric nurses commonly suffer from physical stress due to heavy lifting and incorrect ergonomics resulting in musculoskeletal disorders such as lower back pain [3]. These can be minimized early in the training phase of the caregivers by monitoring ergonomics and giving feedback to trainees on their performance. This entails a need for a system, which is readily available, works in real time and is inexpensive.