For this learning module, you will need:
A collaborative robot is a robot that can be used in a state which is purposely designed to work in direct cooperation with a human within a defined workspace. Collaborative Robots differ in design from industrial robots because they are fitted with a various safety measures depending on application that are to limit risk to the operator.
Collaborative robots may have some or all of these features activated depending on their specific application
Safety-rated monitored stop This safety feature means the robot stops when the operator enters the collaborative workspace.
Hand guiding (Force torque sensors at the robots wrist or at the robots actuator are required to achieve these applications.)
Speed and separation monitoring This type of collaboration is achieved when different safety zones are delimited in the robot workspace. Certain zones will allow maximum speed for the robot whilst others will require lower speeds. These can be set by various means ie visually or by use of monitoring systems.
Power and force limiting by inherent design or control The design and control of the robot is such that it is able to feel abnormal force being exerted on it’s body. Once it hits something the actuators and brakes work to provide less force in the direction of impact. Robots either stop or respond by moving in the other direction.
The safe use of robots is covered by the International standards for Robots and robotic devices ISO 10218-1 and ISO 10218-2 along with the Technical Specification specific to collaborative robot’s ISO/TS 15066:2016 Robots and robotic devices — Collaborative robots
It must be noted that each new situation a collaborative robot is programmed for and all new end effectors applied to that robot require an independent risk assessment.
4. The enabling switch must be held in the centre position in operating modes T1, T2 and CPR in order to be able to jog manipulator.
5. USB connection – archiving data only for FAT32 – formatted USB sticks
6. Enabling switch
7. Identification plate
Collaborative robots have safety features which allow them to be used collaboratively with humans. They can however still cause injury and even death if not integrated and/or programmed and/or used correctly.
It is the responsibility of the owner to make sure the robots are correctly installed and sufficient safety protocols are in place. It is the responsibility of the programmer to assess the risks of each application. It's the responsibility of the user to follow the correct protocols put in place by both the owner and the programmer and to use the robot for the function it has been programmed.
A risk assessment must be completed at the commencement of every new project which uses equipment housed the DFL’s Collab.
A ‘New Project’ is defined as any combination of the following events taking place:
For these reasons, please consider the scope of your project and anticipate the above factors to ensure your initial risk assessment will cover the full extent of your project. You may wish to perform the risk assessment in multiple locations and configurations to broaden the effective scope of your risk assessment.
To complete a risk assessment the programmer is required to fill out a manual form that can be downloaded here. This form must be signed by a DFL Collab staff member before operating your new project.
The robotics collab room has designated areas marked on the floor.
The standard risk assessment for the DFL robotics collab requires that:
If the robots are moved from this position a new risk assessment must be completed. If the user is required to stand over the yellow line for the program a new risk assessment must be completed.
Check all risk assessment procedures and paperwork have been completed and approved by the DFL staff for the project you will be running.
Make sure the robot arm and tool/end effector are properly and securely bolted in place.
Never use the robot if it is damaged, for example if joint caps are loose, broken or removed
Make sure the robot arm has ample space to operate freely that the area you are using is free from clutter.
Before operating the robot make sure to warn people to stand outside of the robot work zone and that you will be operating the robot.
Familiarise yourself with the safety stops
Turn on the robot via the green button on the bottom corner of the sunrise cabinet. The smartpad pendant will go through its start-up procedure.
Always be aware of robot movement when using the smartpad pendant and stand in the safe operating zone marked on the floor.
Whenever the robot is turned on or rebooted it is important the the following precudures are followed.
If there are any other errors on smartpad pendent please ask staff for assistance.
The robot is now ready to use.
General – Manual mode is the mode for setup work. Setup work is all the tasks that have to be carried out on the robot to enable automatic operation. Setup work includes jogging, teaching and program verification.
The following must be taken into consideration in manual mode:
New or modified programs must always be tested first in Manual Reduced Velocity mode T1
This is to check that the manipulator and it’s tooling does not project beyond the safe work zone. That workpieces, tooling and other objects do not become jammed as a result of the robots motion, nor that they lead to short circuits or be liable to fall off.
All setup work must be carried out, where possible, from behind the safe operating line.
Setup work in T1 - If it is necessary to be in the safeguard zone, having more than one person should be avoided. Anyone in the safeguard area must have an enabling device, have and unimpeded view of the robot and have eye contact between all persons in the room at all times.
The operator must be positioned so that they can see into the danger area.
Unexpected motions of the manipulator cannot be ruled out ie in event of a fault. For this reason an appropriate clearance of around 500mm must be maintained between persons and the manipulator (including tool) This figure may change specific applications and must be decided by the user on the basis of a risk assessment.
Setup work in T2 - If it is necessary to carry out setup work from inside the safeguard area, the following must be taken into consideration in the operating mode Manual High Velocity T2.
This mode may only be used if the application requires a test at a velocity higher than that is possible in T1 mode
Teaching is not permissible in the operating mode.
Before commencing the test, the operator must ensure that the enabling devises are operating. The operator must be behind the safety line and out of the danger zone. There must be no one present in the safeguard area. It is the responsibility of the operator to ensure this.
Automatic mode – Automatic mode is only permissible in compliance with the following safety measures
All safety equipment and safeguards are present and operational
There are no persons in the system (cell) or the requirement for collaborative operation in accordance with EN ISO 10218 have been met
The defined working procedures are adhered to:
The majority of our applications will be run in T1 mode where the operator is required to hold the smartpad whilst holding down both the enabling switch and the play button. Programs are not to be run in automatic mode without the approval and overseeing of the DFL staff.
CCR mode – Is the operating mode which can be selected when the robot is stopped by the safety controller for either violating an axis specific or cartesian monitoring space, Orientation of a safety orientated tool is outside the monitored range. Robot violates a force or torque monitoring function, a position sensor is not mastered or referenced, a torque sensor is not referenced. After changing to CRR mode the robot may once again be moved.
The operating mode can be set with the smartPAD using the connection manager. On the smartPAD, turn the switch for the connection manager to the right. Select the operating mode then turn the switch for the connection manager to the left. The selected operating mode is now active and is displayed in the navigation bar of the smartHMI.
Coordinate systems or frames determine the position and orientation of the robot and an object in space.
World coordinate system - The world coordinate system is a permanently defined Cartesian coordinate system. It is the root coordinate system for all other coordinate systems, in particular for base coordinate systems and the robot base coordinate system. By default, the world coordinate system is located at the robot base.
Robot base coordinate system - The robot base coordinate system is a Cartesian coordinate system, which is always located at the robot base. It defines the position of the robot relative to the world coordinate system. By default, the robot base coordinate system is identical to the world coordinate system. It is possible to define a rotation of the robot relative to the world coordinate system by changing the mounting orientation in Sunrise Workbench. By default, the mounting orientation of the floor-mounted robot is set (A=0°, B=0°, C=0°).
Flange coordinate system - The flange coordinate system describes the current position and orientation of the robot flange centre point. It does not have a fixed location and is moved with the robot. The flange coordinate system is used as an origin for coordinate systems which describe tools mounted on the flange.
The following coordinate systems can be set by the user. These systems are to locate a workbench relative to the robot base and a tool relative to the flange.
Tool coordinate system - The tool coordinate system is a Cartesian coordinate system which is located at the working point of the mounted tool. This is called the TCP (Tool Centre Point). Any number of frames can be defined for a tool and can be selected as the TCP. The origin of the tool coordinate system is generally identical to the flange coordinate system. The tool coordinate system is offset to the tool centre point by the user.
Base coordinate system - In order to define motions in Cartesian space, a reference coordinate system (base) must be specified. As standard, the world coordinate system is used as the base coordinate system for a motion. Additional base coordinate systems can be defined relative to the world coordinate system.
A robot's work envelope is area that the robot can reach. This distance is determined by the length and reach of the robot's arm. A stationary robot can only perform within the confines of this work envelope.
LBR iiwa 14 R820 working envelope, side view
LBR iiwa 14 R820 working envelope, top view
Within the work envelope the robot has the following range of motion and maximum speed for each axis.
Our KUKA LBR iiwa 14 R820 robots have a rated payload of 14kg. This is the weight that the robot can lift. This payload must include the weight of any end effector attached to the arm and the weight of the product being lifted.
Just like a human arm , you need to be aware that you can lift a more weight if you arm is bend and closer to your body than with your arm fully extended. For all payloads on the robots, the load center of gravity refers to the distance from the face
of the mounting flange on axis A7.
Load Centre of Gravity
Permissible mass inertia at the design point (Lx, Ly, Lz) is 0.3 kgm².
LBR iiwa 14 R820 payload diagram
The stopping distance is the axis angle traveled by the robot from the moment the stop signal is triggered until the robot comes to a completed standstill.
The stopping distances were measured using the robot-internal measuring technique with rated payloads. The wear on brakes depends on many factors including operating mode, application and the number of STOP 0 stops triggered.
The table shows the stopping distances and stopping times after a STOP 0
(category 0 stop) is triggered.
The values refer to the following configuration:
It is possible to train/program the robot in different types of motions. These motions are useful in various applications that will become more obvious whilst using the robot. Always be aware of the coordinate system you are in when training the robot or you might get unexpected results when testing your program.
The robot guides the tool centre point (TCP) along the fastest path to the end point. The fastest path is generally not the shortest path in space and is not always a straight line. As the motions of the robot axes are simultaneous and and rational curved paths can be executed faster than straight paths.
PTP is a fast positioning motion. The exact path of the motion is not predictable or controlled by the programmer but is always the same if the general conditions have not changed.
The robot guides the TCP at the defined velocity along a straight path in space to the end point. In a LIN motion the robot configuration of the end pose is not considered.
The robot guides the TCP at the defined velocity along a circular path to the end point. In the CIRC motion the robot configuration of the end pose is not considered.
The motion type SPL enables the generation of curved paths. SPL motions are always grouped together in a spine blocks. The resulting paths run smoothly through the end points of the SPL motion. Curved lines are achieved by grouping together 2 or more SPL segments. If a single segment is executed the result is the same as for a LIN command.
Spline motion type – Spline is a motion that is particularly suitable for complex curve paths. With a spline motion, the robot can execute these complex paths in a continuous motion. Such paths can also be generated using approximated LIN and CIRC motions however splines are smoother as they programmed in spline blocks which are executed in one smooth motion. The motions in a spline block are called spline segments.
In a cartesian spline motion the robot configuration of the end pose is not taken into account.
The configuration of the end pose of a spline segment depends on the robot configuration at the start of the spline segment.
The following motions are known as CP (Continuous Path) motions: LIN, CIRC, SPL and CP spline blocks. The following types of motion can be programmed as segments of a CP spline block: LIN, CIRC and Polynormal motion (SPL)
The following motions are known as JP (Joint Path) motions: PTP, and JP spline blocks. The following types of motion can be programmed as segments of a JP spline block: PTP
Due to the axis position, Cartesian motions of the robot may be limited. Due to the combination of axis positions of the entire robot, no motions can be transferred from the drives to the flange ( or to an object on the flange like a tool) in at least one Cartesian direction. In this case, or if very slight Cartesian changes require very large changes to the axis angles, singularity positions are created.
The flexibility due to the redundancy of a 7 axis robot requires 2 or more kinematic conditions ( ie extended position, 2 rotational axes coincide) to be active at the same time in order to reach a singularity position. There are 4 different robot position in which flange motion in one Cartesian direction is no longer possible. Here only the position of 1 or 2 axes is important in each case. The other axes can take any position.
A4 Singularity – The Kinematic singularity is given when A4 = 0° This is called the extended position. Motion is blocked in the direction of the robot base or parallel to axis A3 or A5. An additionally kinematic condition for this singularity is reaching the workspace limit. It is automatically met when A4 = 0°.
Extended robot arm position causes a degree of freedom for the motion of the wrist root position of axes A3 and A5 can no longer be resolved.
A4/A6 Singularity – The kinematic singularity is given when A4 = 90° and A6 = 0°. Motion parallel to axis A6 and A2 is blocked
A2/A3 Singularity – The kinematic singularity is given when A2 = 0° and A3 = ±90° (⫪/2). Motion is blocked in the direction of the robot or parallel to axis A2 or A5
A5/A6 Singularity – The kinetic singularity is given when A5 = ±90° (⫪/2 and A6 = 0°). Motion parallel to axis A6 is blocked.
The configuration of the LBR with its 7thxis allows the robot arm to move without the flange moving. In this null space motion, all axes move except A4 the ‘elbow axis’. In addition to the normal redundancy, it is possible under certain circumstances , that only sub chains of the robot can move and not all axes.
All the robot positions in this category have in common that slight Cartesian changes result in very large changes in Axis angles. They are very similar to the singularities in 6-axis robots, the LBR too, a division is made into the position part and the orientation art of the wrist root point.
Wrist Axis Singularity – Wrist Axis singularity means the axis position A6 = 0°. The position of axes A5 and A7 can thus no longer be resolved. There is an infinite number of ways to position these two axes to generate the same position on the flange.
A1 Singularity – If the wrist root point is directly over A1, no reference value can be specified for the redundancy circle according to the definition above. The reason for this is that any A1 value is permissible here for A4 = 0°. Every axis position for A1 can be compensated for with a combination of A5, A6 and A7 so that the flange position remains unchanged
A2 Singularity – With an extended ‘shoulder’ the position of axes A1 and A3 can no longer be resolved according to the pattern above.
A2/A4 Singularity - If A1 and A7 coincide, the position of axis A1 and A7 can no longer be resolved according to the pattern above.
NOTE: System- dependent singularities can be avoided in most cases by a suitable elbow position
Jogging is the term used when you move the robot. When jogging the robot, you first need to set the coordinate system you would like to move in. This is done by pushing the jogging options button.
You can bring up the options for jogging the robot in the jogging options button.