When you mention a robotic hand applied for industrial purposes, what comes into the minds of many is a robust gripper with two or three fingers. You can’t blame them since such models have been utilized in different industries for a long time now. Such hands perform simple basic movements. Unfortunately, there has been a scarcity of mechanized hands that can perform delicate tasks. This is contributed largely by the inadequacy of technical abilities. Today, however, the story has changed thanks to fruitful interactions between microelectronics and micro-engineering. We can now expect to see robot hands with fingers and moving joints that behave like human hands.
Basically, the human hand is among the most versatile natural tool man has ever come across. It has unique advantages that scientists seem to be enthusiastic to replicate in their evolutionary models of mechanized hands. Fortunately, their dream is now possible since a hand that resembles that of man has actually been created. The gripper that’s driven by Brushless DC Servo Motors and controlled through bus technology was created by the German Aerospace Center in partnership with the Harbin Institute of Technology (HIT).
To create a robot hand that can function as skillfully and versatile as that of humankind, it should contain a minimum of 4 fingers. The machine uses the first 3 fingers to grasp conical objects while the thump offers support. So, this hand design by DLR and HIT features a thumb and 3 fingers each with four joints. The joints have three levels of flexibility while the thumb’s flexibility level is four. Designers incorporated high-performance transmission channels to manage the distinct mobility attained through this gripper. Control of the mechanized gripper is attained through a system that must support high-volume computing at great speeds especially when the hand engages in intricate tasks. So, the control unit for the HIT-DLR model employs a specially designed 25 Mbps bus.
Providing “Nerve” Functions
Originally, engineers moved robot gripper fingers through the help of cable pulls. Fortunately, today’s micro-engineering can enable the insertion of a motor into the finger. This motor feeds the control unit with information about the desired position and working data. This aspect is not only crucial to the gripper’s overall function but also allows the actuator to exude its maximum power.
The angle and torque sensors are installed at the joint of every finger. The two sensors function separately and at superb resolution. The data necessary to ensure this level of performance is provided by a bus. They also need rapid feedback to compare the setpoint and the exact value. So, the necessary data here is fed to an integrated circuit, usually, FPGAs via external serial connectors between the control processing unit and the gripper.
The control unit is basically a PCI card embedded with a signal processor. It is then installed in a regular computer where an operator can now manipulate the hand through a user-friendly computer interface.
Providing Muscle Power
Since each finger is controlled separately, it will need several separate actuators. So, this hand uses 12 16-mm diameter EC brushless DC motors and analog sensors. You may see varieties of such motors here. It is possible to join these motors with components of similar diameter to create a single solid unit. The right motors for this type of mechanized hand should be ones that respond to control instructions quickly. The types of sensors installed in this hand send information about its actual position as well as carry information back to the control unit at 8 bits (or more) resolution. The sensors and motor combine into a solid unit that’s about 28mm long, 16mm external diameter, and 31g in weight. The choice of components here is focused on limiting the speed of rotational motion and enhancing torque of the hand.
The success of the robot hand by HIT-DLR could be attributed to the proper integration of microelectronics and micro-engineering. This enabled delicate and precise manipulation of the sensitive hand. The actuator and bus technology came in handy to allow fast transmission of data and feedback too. This shows that if engineers have an innovative concept and the basic components, creating machines that were impossible in the past is now possible.