Haptic Control of Excavator for Dismantling Process

The number of dismantling sites for buildings has been rapidly increased and these processes are very dangerous. Many research papers have been published addressing the development of a remote controller for the dismantling equipments. In our lab, a novel concept of applying haptic control is proposed for the remote control of excavator- like dismantling equipment. As a haptic device system, this controller is designed to improve the operability of the excavator. So, we research all the dynamic analysis of excavator to design the haptic device. Then, the hydraulic system of excavator which uses the proportional valve and pressure transmitter is also studied. And parameter estimation of excavator is carried out with least square method. And we simulate the real excavator, and operator can control the real excavator intuitively with this new model of haptic device.

Fig. 1 Introduction of haptic device for excavator

Electrical Control System for Excavator

Solar 015 Super (Doosan Infracore, Co., Ltd.) is used to make the testbed for haptic device. Proportional valves and wire-encoders are installed in this mini excavator. This setup is shown in figure 2. So excavator can be controlled with PC through proportional valve. And angle of link can be acquired from the length of cylinder stroke with wire-encoder. After all, trajectory control of boom, arm and bucket link is carried out. Additionally, to estimate the external force, pressure transmitters are setup on the cylinder. 6 transmitters which can measure up to 400bar are installed at the inlet and outlet of boom, arm and bucket cylinder like figure 2.

Fig. 2 Control system of excavator

Load Estimation for Haptic Device

There are also many studies about dynamics of excavator. But parameters which are used in dynamics formulation are difficult to know: inertia of link, friction of joint and cylinder, etc. So some methods, for example least square method or Newton¡¯s methods are proposed to estimate the values of parameters. First dynamics formulation is shown like following equation.

We use the Matlab Toolbox and find the excavator parameter, so we can calculate the load on bucket. And with this load estimation result, operator can feel the external load. Figure 3 shows the load estimation result.

Fig. 3 Load Estimation Results (on bucket tip)

Haptic Device for Excavator

We designed several haptic device for excavator. First, we focus on intuitive and comfortable device. Basically, excavator has 4 DOF. So we designed 4 DOF haptic device. Designed haptic device for excavator are shown figure 4. Recently we make the haptic device and make the visual C++ control program. And for haptic force feedback, we installed three maxon motor at each joint. So operator can control the excavator with one-hand intuitive control and feel the external force exerted to the bucket tip.

Fig. 4 Control system of excavator

Reference

  1. Dongnam Kim, Kyeong Won Oh, Daehie Hong, Yoon Ki Kim, Suk-Hie Hong, "Motion Control of Excavator with Tele-Operated System," June, 24-27, ISARC2009
  2. Kyeong Won oh, Dongnam Kim, Nam Hoon Kim, Daehie Hong, Yun Ki Kim, Sukhie Hong, "Wearable Joystick System and Controller Design for Hydraulic Excavator," Nov, 11-13, ASPEN 2009