Analysis of the effects of time delays on the teleoperation of a mobile robot in various modes of operation

Abstract

The effect of time delay on the ability of a human operator to complete a task with a tele-operated mobile-robot is investigated using two systems, two different ways of interacting with the mobile-robots and several different environments. Design/methodology/approach: Tele-operators were observed completing a series of tasks using a joystick to control a mobile-robot while time delays were introduced to the system. They sat at a computer and viewed scenes remotely on a screen. Cameras were either mounted on the robot or mounted externally so that they viewed both the environment and robot. Tele-operators completed the tests both with and without sensors. One robot system used an Umbilical Cable and one used a radio link. Findings: In simple environments, a tele-operator may perform better without a sensor system to assist them but as time delays were introduced then there were more failures. In more complicated environments or when time delays were longer then teleoperators performed better with a sensor system to assist. Tele-operators may also tend to perform better with a radio link than with an umbilical connection. Research limitations/implications: Tele-operated systems rely heavily on visual feedback and experienced operators. This paper investigates the effect of introducing a delay to the delivery of that visual feedback. Practical implications: The paper suggests that in simple environments with short time delays then the amount of sensor support should be small but in more complicated environments or with longer delays then more sensor support needs to be provided. Originality/value: Results from imposing time delays on a tele-operated mobile-robot are presented. Effects on the task of different ways of viewing activity on a computer display are presented, that is with cameras mounted on the robot or cameras mounted externally to view both the environment and robot. Results from using sensors to assist tele-operators are presented. The paper suggests that the amount of sensor support should be varied depending on circumstances.

Unmanned Ground Vehicle with Virtual Reality Vision

“…We restricted our comparison to the ADORA [9] and RAPOSA [11] UGVs, since both have similar design objectives as our UGV, specifically: mobility, victim identification, mapping (i.e., ability to generate 3D maps, of the surrounding areas and present them in an intuitive way), and HRI (i.e., ability to provide the operator with visual information about the robots' immediate surroundings). In addition to that, since delay is an important factor in teleoperated UGVs [23,24] and because our UGV relies on TCP for transmitting video over WiFi, we studied the effect of delay on received video over a range of distances.…”

Analysis of successes and failures with a tele-operated mobile robot in various modes of operation

“…Ultrasonic ranging was selected as it was simple and robust. 18 The apparatus consisted of a parallel interface, which provided an input to a microcomputer, a dedicated controller with analogue interfacing, DC servo-amplifiers and joystick. 5 Two 40 KHz ultrasonic transmitter and receiver pairs could be mounted at the front of the mobile robot.…”

“…Mobile robots and unmanned vehicles are being increasingly used (and considered for future use) for assisting powered wheelchair users, 6,7 in nuclear plants, 8,9 for search and rescue, 10,11 surveillance, 12,13 security 14,15 and inspection. 16,17 Tele-robotics enable a robot to be remotely operated from outside a hazardous environment and the real challenge in unstructured and difficult environments such as hazardous areas is primarily the control of mobile robots 18,19 with some assistive algorithms. 20,21 Tele-operated mobile robots are generally directed along a path using manual controls and the master system has often been a joystick [22][23][24][25] although other input devices are available, for example, a pointer, 26 switches [27][28][29] or custom built devices such as virtual reality interfaces.…”

Teleoperation of a mobile robot with time-varying delay and force feedback

“…This section shows experiments of teleoperation of a mobile robot using the proposed control scheme, which joins the human operator's commands and a remote controller, based on a fusion function (30) and an enhanced predictor (4), both depending on the time delay and the crash probability.…”