Experimental Research of Force Feedback Dataglove Based on Pneumatic Artificial Muscle

Force feedback dataglove is an important interface of human-machine interaction between manipulator and virtual assembly system, which is in charge of the bidirectional transmission of movement and force information between computer and operator. The exoskeleton force feedback dataglove is designed taking the pneumatic artificial muscle as actuator, meanwhile, its structure and work principle are introduced, and the force control problem is analyzed and researched by experiment. The mathematic model of grasping rigid object for finger is established. Considering the friction of tendon-sheath system and finger deformation, the closed-loop force control for a single joint, a single finger and multi-fingers are studied respectively by the feedforward proportional-integral（PI） control method with variable arguments. On the premise of the force smoothness, the control error of the force exerted on the finger joint is in the range of ±0.25 N, which meets the requirement of force feedback. By experimental analysis, the reason of force fluctuation is that the finger joint has a small amplitude quiver, and the consistent change tendency of the force between proximal interphalangeal（PIP） joint and distal interphalangeal（DIP） joint results from their angle coupling relationship.

FORCE FEEDBACK DATAGLOVE BASED ON PNEUMATIC ARTIFICIAL MUSCLES

An exoskeleton force feedback dataglove is developed, which uses the pneumatic artificial muscles as actuators. On the basis of the simplified hand model, the motion equation is deduced according to the theory of Denavit-Hartenberg. The model of the equivalent contact forces exerted by the object on the finger is proposed. By the principle of virtual work, the static equilibrium of finger is established. The force Jacobian matrix of finger is calculated, and then the joint torques of the finger when grasping objects are obtained. The theory and structure of the force feedback datagolve are introduced. Based on the theory of motion stabilization of four-bar linkage, the flexion angles of joints are measured. The torques on finger joints caused by the output forces of pneumatic artificial muscles are calculated. The output forces of pneumatic artificial muscle, whose values are controlled by its inner pressure, can be calculated by the joint torques of the finger when grasping objects. The arms of force, driving torques and the needed output forces of pneumatic muscle are calculated for each joint of the index finger. The criterion of output force of pneumatic muscle is given.

A New Kind of Bend Sensor

A new kind of bend sensor is introduced. It can be used to detect the bend angle of an object or inclination between two objects. It has characteristics of small size, lightweight, high reliability, fine flexibility and plasticity. When this bend sensor is used with a proper converting circuit, it can implement dynamic measuring the bend angle of an object conveniently. The application of the bend sensor in dataglove is also described.

Hand Interface in Traditional Modeling and Animation Tasks

3-D task space in modeling and animation is usually reduced to the separate control dimensions supported by conventional interactive devices. This limitation maps only patial view of the problem to the device space at a time, and results in tedious and un natural interface of control. This paper uses the DataGlove interface for modeling and animating scene behaviors. The modeling interface selects, scales, rotates, translates,copies and deletes the instances of the prindtives. These basic modeling processes are directly performed in the task spacet using hand shapes and motions. Hand shapes are recoginzed as discrete states that trigger the commands, and hand motion are mapped to the movement of a selected instance. The interactions through hand interface place the user as a participant in the process of behavior simulation. Both event triggering and role switching of hand are experimented in simulation. The event mode of hand triggers control signals or commands through a menu interface. The object mode of hand simulates itself as an object whose appearance or motion inlluences the motions of other objects in scene. The involvement of hand creates a diversity of dyndric situations for testing variable scene behaviors. Our experiments have shown the potential use of this interface directly in the 3-D modeling and animation task space.