############## DeCIMo experiment dataset #################

This experiment consists in recording full body motion of participants undergoing external perturbation at shoulder height with different sensory conditions. 

The following experiment received ethical approval from an ethics committee (Comité de Protection des Personnes, EudraCT: 2021-A01378-33}) and all participants signed an informed consent form relative to the processing of their data. 
The experiments were carried on 21 healthy young adults (10 females, 11 males). All were between 20 and 38 yo with a mean age of
27.2 (std:4.2). Mean mass was 70.2 (std:12.1) kg and height was 1.74 (std:0.08) m. Laterality test was performed (see related paper*).
All but one subject were considered having an overall right side preference, mean results of the test: 9.45 (std:3.28).

## About data recording ##
Participants motion was recorded using 45 reflective markers and a 23 Qualisys camera system (200Hz). 
The markers were placed on participants following standardised anatomical landmarks*. 
The output signal of the force sensor was processed using a Butterworth low pass filter with a 5Hz cutoff frequency without phase shift. 
The force sensor was synchronised with the motion capture software.
Tree reflective markers were also placed along the pole in order to retrieve the exact direction of the push. 

### About the series (SI/NI) ##
To assess the effect of sensory impairment on step triggering, the experiment was divided into two blocks performed in random order: 
 - Sensory Impaired (SI) or No Impairment (NI). For SI trials participants wore a noise-canceling headset (3M PELTOR Optim II, 30 dB) with mounted opaque plastic sheets to limit peripheral vision (see \cref{PerturbationsLoc}). %The two blocks were randomly ordered to minimize order effects. 

## About the perturbations ##
We investigated the effect of perturbation angles on step triggering using five different angles (0, 45, 90, 135, 180deg see related paper*). 
A trial corresponded to a single reaction to an external perturbation. 
The perturbations were applied using a pole at the extremity of which we placed a force sensor (U9C 0.5kN, HBK, Germany) followed by a rounded steel plate. During the experiments the pole was held as horizontal as possible using a mounted spirit level. The perturbations occurred at shoulder height for five different angles, with intensities divided into three ranges (`Low', `Medium', `High').
Each perturbation lasted for $0.74\pm 0.14s$. The perturbations were sharp bell shaped with average maximal intensities of $54\pm 12N$, $68\pm 13N$ and $88\pm 20N$, respectively for `Low', `Medium' and `High' ranges of intensity. Ranges of intensity were selected to ensure balance recovery with and without steps, based on the literature \citep{Robert_2018} and observations during pilot experiments.
Perturbations of the same intensity level and angle were repeated twice. Participants received six perturbations at the same angle during each block, for a total of 30 trials per block (5 Angles $\times$ 3 Intensities $\times$ 2 Repetitions). 

Perturbations angle and intensity were randomized within each block. 
Participants had no prior indication that a perturbation was coming except from peripheral vision and footstep sounds for NI trials.
The following rules were also given to participants before the experiment: 
- Stand still and look straight ahead, with feet side by side in a stance not wider than hip width.
- Maintain a stable final position after the perturbation.




*further information and references can be found in the following articles:
https://doi.org/10.1016/j.jbiomech.2023.111703


for any question regarding the dataset please contact:
Thomas.chatagnon#at#inria.fr