Lorenzo Masia

Robot-aided assessment of wrist proprioception

 It has long been recognized that impaired proprioception may severely affect the control of balance and voluntary movements. However, clinical assessment of the impact of proprioceptive deficits on motor functions has been difficult to elucidate for two reasons – the qualitative nature of available clinical tests and the lack of instrumentation to accurately manipulate human limbs and consequently to obtain accurate and reliable measures of proprioceptive acuity.  The recent advent of haptic robotic interfaces designed for sensorimotor rehabilitation in hospitals has improved the ability to accurately manipulate joint movements. Such technology offers a tool to quantitatively evaluate proprioceptive function.

 A new method based on the use of a three-degrees-of-freedom robotic device to deliver accurate wrist kinematics and to assess wrist joint proprioceptive acuity is proposed. Research protocol consists of psychophysical threshold hunting method to determine acuity for two different degrees of freedom by means of a robotic manipulandum. Two different stimuli are presented in each trial: a stimulus of fixed value (standard stimulus) and the other with variable amplitude across trials (comparison stimulus) and always higher than the standard.  After each trial, the participant verbally indicates which stimulus is “larger” (i.e. which of the two movements has a larger displacement).

proprioception method

Figure 1. Left: The Wrist robot, a three-DoF manipulandum used for the experiments. Center: Experimental setup. Subjects grasped the handle of the wrist robot while auditory cues were masked by pink noise from headphones and vision was occluded  through opaque goggles. Right: Stimuli presented. During each trial, a standard (15°) and a comparison displacement (variable but >15°) were presented in random order.

Based on the subject’s response, a comparison stimulus is selected for the subsequent trial. Acuity is defined as the stimuli amplitude difference such that the subjects identify the comparison as larger with a frequency of 75%.



Figure 2: Example of a psychometric function of subject 1. Circles represent binned responses recorded during the experimental procedure; vertical line depicts the mean (acuity threshold) of the Cumulative Gaussian. The plot presents a threshold of 0.39 in logarithmic scale – corresponding to 2.46° in linear scale.

Results obtained highlight the efficacy and intrinsic simplicity of the proposed method marking the milestone for further investigations and characterization of proprioceptive acuity in pathologies and age-related degradation of sensory-motor functions.




Cappello, L., Elangovan, N., Contu, S., Khosravani, S., Konczak, J., & Masia, L. (2015). Robot-aided assessment of wrist proprioception.Frontiers in human neuroscience9.

Cappello, L., Contu, S., Elangovan, N., Khosravani, S., Konczak, J., & Masia, L. (2014, November). Evaluation of wrist joint proprioception by means of a robotic device. In Ubiquitous Robots and Ambient Intelligence (URAI), 2014 11th International Conference on (pp. 531-534). IEEE.

Contu, S., Cappello, L., Konczak, J., & Masia, L. (2015, August). Preliminary analysis of non-dominant proprioceptive acuity and interlimb asymmetry in the human wrist. In Engineering in Medicine and Biology Society (EMBC), 2015 37th Annual International Conference of the IEEE (pp. 3598-3601). IEEE.

Cappello, L., Contu, S., Konczak, J., & Masia, L. (2015, August). Wrist proprioceptive acuity: A comprehensive robot-aided assessment. InEngineering in Medicine and Biology Society (EMBC), 2015 37th Annual International Conference of the IEEE (pp. 3594-3597). IEEE.

Marini F, Squeri V, Morasso PG, Konczak J and Masia L. (2016). "Robot-Aided Mapping of Wrist proprioceptive acuity across a 3D workspace". accepted for publication on PLoSONE.


New Journal on Rehabilitation Technology

Journal of Rehabilitation and Assistive Technologies Engineering (click here)

Lorenzo MASIA (Associate Editor)



Journal Topics

Research Topic (click here)





International Conference on Rehabilitation Robotics

Singapore 11th-14th August 2015 Hosted by NTU

General Chair: Wei Tech ANG

Program Chair: Lorenzo MASIA



IEEE BIOROB 2016 (clickhere)



  • L. Masia, Nanyang Tech. University
  • S. Kukreja, National University of Singapore





Lorenzo MASIA Editor of Biorob 2014



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