can be equipped with various tools for visual inspection with
appropriate lighting and cameras, special gripper jaws, or lasers
for cutting metal and concrete. Depending on the application, the
robot can be mounted on a static or mobile station, such as an
industrial robot or a gantry.
Always following its nose
The snake-arm is capable of performing a whole range of inspection and maintenance tasks, without any direct support from
its environment. It can be navigated freely across open spaces.
The robot is controlled by proprietary software which enables
the operator to control the snake-arm by means of the nose-following principle. A command is transmitted to the tip of the
snake-arm with a joypad and the rest of the joints follow this
specified path. In other words, if the operator steers the tip clear
of an obstacle, the rest of the snake-arm will follow suit. With
This highly complex application requires a very specific drive.
this technology, it becomes a lot easier for people to work in hazardous environments, yet humans are not eliminated completely,
explains Rob Buckingham, managing director of OC Robotics.
Brushless DC motors for flexible movements
In a human arm, the tendons connect the muscles to the bones
of the joints. Similarly, in the snake-arm, stainless-steel wires
are connected to the individual joints of the robot like tendons. Each individual wire is connected to a maxon motor. The
snake-like wriggling movements are the result of the motors
transmitting the mechanical power to the snake arm, where the
individual joints are located. Depending on the version, up to
50 motors are installed in each snake-arm, but are not located
directly in the arm, but rather in an actuator pack in the base
of the robot. This is advantageous as the electronics are more
easily accessible and not exposed to the confined and hazardous environments. Another area of use for the motors is the different tools on the snake-arm’s head. Here, one or two motors
are responsible for the movements of (for example) the gripper
jaws or swage tool.
The biggest challenge to the drives is that they have to provide
a high enough power output inside of a compact design. Therefore, the brushless maxon EC-max 30 DC motor (60 W) and the
ceramic version of the GP32 planetary gearhead are used for this
highly complex application. The heart of the motors is the ironless winding – with the benefits inherent to the physical design,
such as zero cogging torque, high efficiency, and excellent control
Special modifications were necessary as a special cable and
fastening holes were required, whilst the planetary gearhead was
modified for the application, and a special housing was developed
for the brake. ECN