Biomedical subjects

Peter H Veltink

Publications and source records attributed to Peter H Veltink.

3 recordsLinked to original sources

PubMed2002

Accelerometer and rate gyroscope measurement of kinematics: an inexpensive alternative to optical motion analysis systems.

A general-purpose system to obtain the kinematics of gait in the sagittal plane based on body-mounted sensors was developed. It consisted of four uniaxial seismic accelerometers and one rate gyroscope per body segment. Tests were done with 10 young healthy volunteers, walking at five different speeds on a treadmill. In order to study the system's accuracy, measurements were made with an optic, passive-marker system and the body-mounted system, simultaneously. In all the comparison cases, the curves obtained from the two systems were very close, showing root mean square errors representing <7% full range in 75% of the cases (overall mean 6.64%, standard deviation 4.13%) and high coefficients of multiple correlation in 100% of cases (overall mean 0.9812, standard deviation 0.02). Calibration of the body-mounted system is done against gravity. The body-mounted sensors do not hinder natural movement. The calculation algorithms are computationally demanding and only are applicable off-line. The body-mounted sensors are accurate, inexpensive and portable and allow long-term recordings in clinical, sport and ergonomics settings.

Acceleration↗

PubMed2002

Standing balance evaluation using a triaxial accelerometer.

This paper presents a new inherently triaxial accelerometer-based system for determining the ability to maintain balance while standing. In this study, the accelerometer was placed at the back of the subject at the approximate height of the centre of mass. The data were processed to obtain five performance parameters. Paired t-tests indicated that the accelerometer measurements were able to distinguish between the different test conditions as well as or better than simultaneous AMTI force platform measurements (P < or = 0.05). The accelerometer system is fully portable, independent of inclination in space, low-cost and allows long term measurements of standing balance.

Electrophysiology↗

PubMed2002

The optimal stimulation pattern for skeletal muscle is dependent on muscle length.

Stimulation patterns can be optimized by maximizing the force-time integral (FTI) per stimulation pulse of the elicited muscle contraction. Such patterns, providing the desired force output with the minimum number of pulses, may reduce muscle fatigue, which has been shown to correlate to the number of pulses delivered. Applications of electrical stimulation to use muscle as a controllable biological actuator may, therefore, be improved. Although muscle operates over a range of lengths, optimized patterns have been determined only at optimal muscle length. In this study, the patterns with up to four pulses that produced the highest isometric FTI were determined at 10 muscle lengths for 11 rabbit tibialis anterior muscles. The interpulse intervals (IPIs) used ranged from 4 to 54 ms. At high muscle length, the optimal stimulation pattern consisted of an initial short IPI (doublet) followed by longer IPIs, in agreement with previous studies. However, at low length, the third pulse still elicited more than linear summation (triplet); furthermore, the relative enhancement of the FTI per pulse was considerably larger at low length than at high length, suggesting that optimal stimulation patterns are length dependent.

Animals↗