This paper investigates the benefits of haptics-based interaction for performing assembly-related tasks in a virtual environment. The research examines the context in which haptic feedback affects user performance and identifies assembly operations that are influenced. Forty participants completed three experiments relevant to virtual assembly: weight discrimination, part positioning, and manual assembly. Each experiment featured a series of trials generated from factorial combinations of performance variables. Subjects were assessed based on task completion time and different measures of accuracy. When compared to visual-only methods, quantitative results show that haptics-based interaction is beneficial in improving performance by reducing completion times for weight discrimination, permits higher placement accuracy when positioning virtual objects, and enables steadier hand motions along threedimensional trajectories. The results also indicate that user accuracy in weight discrimination is dependent on hand dominance when manipulating the virtual object combined with the provided sensory information. Virtual reality, haptics, human computer interaction. INDEX TERMS: Jayaram et al. [1] defined four key elements of a virtual environment (VE): three-dimensional stereoscopic viewing, position tracking, multiple sensory stimuli, and object-to-object interaction. Virtual reality (VR) technology has been applied to many engineering areas such as product design, maintenance and assembly planning. Gomes de Sa and Zachmann [2] demonstrated the utility of VR for evaluating a prototype of an automobile design. Virtual assembly is the ability to assemble CAD models of parts using a three-dimensional immersive interface with natural human motion [3] . One example of a virtual assembly simulation is the Virtual Assembly Design Environment (VADE) developed at Washington State University [4] . This system was capable of exchanging geometric data of part models and assembly constraints from Pro/Engineer to an immersive virtual environment. As the use of VR expands, researchers continue to investigate methods for increasing the realism experienced within virtual simulations. These simulations rely on visualization as a primary method of conveying information. Although incorporating haptics within a virtual environment provides users with a method of interacting with virtual objects, it increases the complexity of virtual environments due to hardware and software requirements. Identifying the benefits of haptics on user performance presents a unique research challenge. The objective of this research is to assess the performance benefits of haptics-based interaction for virtual assembly. To achieve this goal, user performance is evaluated in completing similar assembly tasks when provided only visual feedback and a second method where both visual and haptic cues are rendered. We will determine whether completion times and user accuracy are influenced by force rendering and distinguish assembly tasks where haptic feedback affects performance. Three experiments were developed based on the perceived value of force information when performing assembly tasks in a real environment. The ability to discriminate weight presents great concern to operators for determining proper handling and manipulation techniques. External forces produced from contact can assure correct placement of mating components in a manual assembly. A third experiment examines the implementation of assistive forces to ensure proper part displacement along a specified trajectory. This can familiarize assemblers with routine hand motions performed for a specific positioning task. Identifying the utility of haptic-based interaction has motivated research efforts from several institutions. In these investigations, researchers have examined the influence of haptic feedback on users' ability to interpret force information or to assist in task completion. Studies concerning haptics that are relevant to virtual assembly include weight discrimination, performing spatial tasks, and manual assembly. In weight comparison studies, researchers have examined users' ability to interpret haptic rendering of weight forces between pairs of objects. Studies performed at Washington State University [13] and Georgia Tech University [14] required participants to interact with paired objects in real and virtual environments. In both studies, participants were able to distinguish the weight of objects more accurately when comparing real objects and in less time than objects in the virtual environment. In haptics-enabled virtual environments, subjects from both studies were able to identify weight quantities in over half of the respective trials. Studies involving haptics-based interaction for spatial tasks have focused on rendering contact forces to assist users in determining the distances between virtual objects. Research conducted by Arsenault and Ware [15] and O'Malley et al. [16] examined haptics assistance for performing a Fitts tapping task. Both studies
Vo et al. REF investigated how haptic feedback affects users' performance in relevant virtual assembly tasks related to weight discrimination, part positioning, and manual assembly.
Assessment of haptics-based interaction for assembly tasks in virtual reality
World Haptics 2009 - Third Joint EuroHaptics conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems
World Haptics 2009 - Third Joint EuroHaptics conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems
Engineering Computer Science