Haptic Error Modulation Outperforms Visual Error Amplification When Learning a Modified Gait Pattern

Abstract

Robotic algorithms that augment movement errors have been proposed as promising training strategies to enhance motor learning and neurorehabilitation. However, most research effort has focused on rehabilitation of upper limbs, probably because large movement errors are especially dangerous during gait training, as they might result in stumbling and falling. Furthermore, systematic large movement errors might limit the participants’ motivation during training. In this study, we investigated the effect of training with novel error modulating strategies, which guarantee a safe training environment, on motivation and learning of a modified asymmetric gait pattern. Thirty healthy young participants walked in the exoskeletal robotic system Lokomat while performing a foot target-tracking task, which required an increased hip and knee flexion in the dominant leg. Learning the asymmetric gait pattern with three different strategies was evaluated: (i) No disturbance: no robot disturbance/guidance was applied, (ii) haptic error amplification: unsafe and discouraging large errors were limited with haptic guidance, while haptic error amplification enhanced awareness of small errors relevant for learning, and (iii) visual error amplification: visually observed errors were amplified in a virtual reality environment. We also evaluated whether increasing the movement variability during training by adding randomly varying haptic disturbances on top of the other training strategies further enhances learning. We analyzed participants’ motor performance and self-reported intrinsic motivation before, during and after training. We found that training with the novel haptic error amplification strategy did not hamper motor adaptation and enhanced transfer of the practiced asymmetric gait pattern to free walking. Training with visual error amplification, on the other hand, increased errors during training and hampered motor learning. Participants who trained with visual error amplification also reported a reduced perceived competence. Adding haptic disturbance increased the movement variability during training, but did not have a significant effect on motor adaptation, probably because training with haptic disturbance on top of visual and haptic error amplification decreased the participants’ feelings of competence. The proposed novel haptic error modulating controller that amplifies small task-relevant errors while limiting large errors outperformed visual error augmentation and might provide a promising framework to improve robotic gait training outcomes in neurological patients.

Rowing Simulator Modulates Water Density to Foster Motor Learning

“…In addition to the applicability of findings of our study to other similar sport skills, e.g., kayaking, canoeing, cycling or running, the current results may also have implications for robot-assisted locomotor rehabilitation. In the field of gait rehabilitation with robotic devices, many research teams attempted to apply assistive and/or resistive forces (Dong et al, 2005 ; Lam et al, 2015 ; Mun et al, 2017 ; Wu et al, 2017 ; Marchal-Crespo et al, 2019 ) to the leg movements to restore the gait function of patients who suffered from spinal cord injury and stroke. Since the adjustment of task difficulty in the training conditions can influence the effectiveness of the movement restoration (recovery) process (Kizony et al, 2003 ), it is important to devise suitable intervention protocols.…”

Learning and transfer of complex motor skills in virtual reality: a perspective review

“…While amplifying errors enhanced skill acquisition in participants who initially demonstrated greater skill, it negatively impacted transfer due to a slightly different coordination strategy [51]. The same group of researchers evaluated the effect of haptic error versus visual error amplification in a VE [52]. Participants who trained a novel asymmetric gait pattern with visual error amplification demonstrated poorer transfer to a free walking condition as compared to the haptic perturbation group.…”

Providing low-dimensional feedback of a high-dimensional movement allows for improved performance of a skilled walking task

“…overground). Many past studies have described using visual feedback to modify gait as skilled locomotor learning 41,42,44,45 . Our results and methodology compare favorably to these past studies; thus, we can best describe our task as a skilled motor task.…”