As a conventional construction machinery, excavator is carrying out heavy and difficult tasks. Due to the diversity and uncertainty of construction site working conditions, this kind of work still relies on manual operation. However, there is no doubt that excavator operation is hard and tiring. The outdoor working environment with high temperature and sun and dust is not only difficult, but also brings great challenges to workers’ health. Therefore, an integrator in North China is trying to carry out this task through manipulator. The project has a relatively simple idea — manipulators installed in the cockpit of the excavator are remotely operated to control the movement and operation of the excavator. This seemingly “simple” requirement, however, takes a lot of work to implement.
There are altogether four operating rods for excavators. According to the operating habits of human hands, one hand controls two operating rods — one joystick (2 degrees of freedom) and one pushing rod (1 degree of freedom). Therefore, the most intuitive plan is to replace human hands with two robotic arms to imitate the existing manual operation habits.
This requires the robot to have three characteristics:
Firstly, being very compact; The operating room is very small, and the location for robot installation is very limited.
Secondly, being flexible; There should be enough freedom for each joint in a narrow space to ensure that there is no unreachable point and no interference when designing the trajectory for the robot.
Thirdly, easily programmed; The manipulator needs to identify the position of the joystick and the pushing rod, so as to ensure that the robot can precisely control the joystick in real time during remote operation. Finally, the collaborative robot gave a satisfactory answer.
ELITE was involved in the development and design of two EC63 (3kg) collaborative robots that replaced the human hands to operate the joystick and the pushing rod. The operator does not need to sit in the crowded excavator operation cabin, but can remotely operate the robot in the remote control cabin to operate the excavator. In this project, ELITE defined the remote control rod as 255 signal positions. The manipulator could identify the position of the joystick and then accurately control the moving position based on the input of the signal, thus comprehensively achieving real-time control of the remote operation.
The 6-joint EC63 collaborative robot supports ±360°rotation, has a working radius of 624mm, and weighs only 13kg. The compact structure and flexible space it can reach allow the robot to easily work in small space.
It’s worth noting that ELITE also designed a seat for the project — two robotic arms drive the excavator during remote operation, and when the crew wants to enter the cockpit, the arms can be moved to the back of the cockpit to leave room for the driver. The feature that collaborative robots can share operating space with human also ensures the safety of human-machine interaction.
The addition of collaborative robots to traditional industries brings imaginations and new ideas.
1. Robot replacements reducing the number of people working outdoors;
2. Realizing the control of multiple excavators in a remote control cabin by CAN bus communication;
3. With ELITE’s internal interfaces for motions, the whole program can be written with only 9 points specified on the joystick and 3 points on the pushing bar;
4. As a pioneering attempt in the construction industry, it is likely to be copied to other outdoor operations;
5. The compact installation space enables the robot to operate the excavator in automatic mode and move the robot to other positions to leave space for operating crews, thus increasing the flexibility of the operation mode;
6. Collaborative robot programming is simple, and the entire project cycle only takes 2 weeks!
In the future, more and more collaborative robots will appear in many traditional jobs, not just excavators.