Design, control and application of a force feedback system in teleoperation

Abstract

The finger-level force feedback system is composed of two parts. The first part is the force feedback device itself. It can provide pressure force feedback to two fingertips: the thumb and the index finger. The use of tendon driven mechanism simplifies the mechanical system and makes it small and light enough to be worn on human hands. A control algorithm is developed for the tendon tension control based on a thin and flexible force sensor.

Force feedback devices have many different levels. Force information may be applied to the entire body, the arm, the hand or the fingers. In this research, the force feedback focuses on the finger tips. Finger-level force feedback is applied by a wearable force feedback system.

Teleoperation is to operate robot manipulators (slave) from a remote site using input devices (master) controlled by human operator. It has been widely used in space engineering, marine applications, dangerous environments and surgical simulations/operations. Telepresence refers to the humen operator's sense of presence in the remote site. One important aspect that can improve telepresence is to use force feedback devices.

Many different finger-level force feedback systems have been developed during the past. A new type of tendon-driven finger-level force feedback system is presented by this research. Compared with other designs, the system has the its advantages. It is light in weight, wearable and has a large working range for the human operator.

Future work includes implementing the Baxter robot for the arm-level force feedback and combining the arm-level force feedback with the finger-level force feedback. The goal is to develop the current finger-level force feedback system into a multi-level force feedback system.

The second part is the sensing part. This part can detect the positions and orientations of the two finger tips, as well as the palm in the 3D space. The two types of sensors used in the system are the non-contact light sensor (the Leap sensor) and the IMU (Inertial Measurement Unit). The sensor data is combined using the extended Kalman filter for a more precise and stable result. By connecting the above two parts together, the force feedback system can detect the positions and orientations of the finger tips, transfer the detected information to the slave side and apply the corresponding force feedback on the finger tips.