Abstract:
This study presents the design of an energy efficient electro-hydraulic control system for a collaborative humanoid robot. Robots can be found in almost every aspect of our lives with different applications such as manufacturing, construction, agriculture, surgery, and transportation. The need for robots is on the rise as they perform certain tasks much faster and with more precision than humans. The lack of them having cognitive ability limits them in certain tasks as human interaction is often needed. Humans are currently better than robots in performing some tasks such as decision making and problem solving. In collaborative robotics, humans and robots are required to work together to achieve a common goal. In most cases, this is achieved by confining both entities in the same space. This allows for better accuracy for these robots with the flexibility and cognition of humans. Furthermore, research lately shows an increase in robots that use hydraulics with most showing that these hydraulics have energy saving abilities in robotic actuation. It is known that hydraulics have a high power to weight ratio thus allowing for more powerful yet compact robots to be built. An electro-hydraulic control system is thus described in this research in which the system allows the human user to manipulate the robot by having it mimic the user’s moves. This approach allows the user to not do any strenuous activities while the robot does the heavy lifting. Furthermore, the system does not need to be reprogrammed for a new task therefore reducing the reconfiguration time of the system. The proposed approach further allows the robot to work in hazardous situations while the user is in a safe environment. The system uses a proportional-integral-derivative (PID) algorithm to control a hydraulic cylinder allowing it to move with the user. Experiments performed to validate the study shows the reaction time as well as energy saving abilities of the system. Additionally, the results show that hydraulic systems have the ability to save energy during stall as well as increasing power density of the robot. Furthermore, an improved response time was recorded for the hydraulic system when being controlled by a remote operator.
