iGripper: A Semi-Active Handheld Haptic VR Controller Based on Variable Stiffness Mechanism

We introduce iGripper, a handheld haptic controller designed to render stiffness feedback for gripping and clamping both rigid and elastic objects in virtual reality. iGripper directly adjusts physical stiffness by using a small linear actuator to modify the spring’s position along a lever arm, with feedback force generated by the spring’s reaction to the user’s input. This enables iGripper to render stiffness from zero to any specified value, determined by the spring’s inherent stiffness. Additionally, a blocking mechanism is designed to provide fully rigid feedback to enlarge the rendering range. Compared to active controllers, iGripper offers a broad range of force and stiffness feedback without requiring high-power actuators. Unlike many passive controllers, which provide only braking force, iGripper, as a semi-active controller, delivers controllable elastic force feedback. We present the iGripper’s design, performance evaluation, and user studies, comparing its realism with a commercial impedance-type grip device.