Investigating the Effects of Combined Kinesthetic and Skin-Stretch Tactile Feedback with a Forearm-Worn Haptic Device

Natural human touch relies on the integrated perception of kinaesthetic and tactile feedback, yet most haptic systems render them independently. In this work, we present a synchronized multimodal haptic system that integrates a grounded force-feedback device with a custom wearable skin-stretch tactile module on the user’s forearm. To evaluate the efficacy of combining these modalities, we conducted a user study (N=18) in a virtual environment where participants performed a stiffness discrimination task for three different conditions: combined feedback mode (COMB), only kinaesthetic feedback mode (KIN), and only tactile feedback mode (TACT). User performance and perceived workload were compared across the three modes. Results demonstrate that the combined modality significantly enhances user performance. Participants achieved higher accuracy in identifying stiffness levels (92% for COMB vs. 62% for KIN) with significantly lower virtual wall penetration depth, fewer virtual contacts, and less applied force. Furthermore, subjective evaluations using the NASA-TLX method indicate that the combined mode induced the lowest overall workload. These findings highlight that integrating coherent kinaesthetic and tactile haptic feedback improves interaction efficiency, system stability, and perceptual accuracy, providing valuable design insights for next-generation visuo-haptic human-computer interfaces.