Smart feedback systems in modern robotics

Transcription

1 Smart feedback systems in modern robotics Aljaž Ogrin Product manager for absolute encoders RLS & Renishaw

2 About the presenter Aljaž Ogrin From company RLS (Rotary and Linear Sensors), Slovenia Specialized in magnetic encoder technologies Associate company of Renishaw global leader of metrology products Electronics engineer Working in Encoder division for 16 years Working closely with the robotic market for past 5 years

3 Abstract & Learning objectives RLS and Renishaw supply feedback systems to the worldwide market. Working closely with robotic market for many years gives us an interesting view of global markets and gives a broad overlook of current market status and hints about trends and future developments in robotic market. Today s Focus: Detecting future trends in which direction(s) robotic builders and end-customers are researching. Analyzing the importance and influence of feedback systems to overall application performance. Industrial and Collaborative Robot market Interesting case studies: Autonomous vehicles, unmanned flying and deep-sea systems

4 Robotic market sectors Industrial (classic) robots for heavy duty factory automatization Smaller task automatization; more versatile Consumer robots; home assistance; intelligent toys Highly specialized applications (military, medical)

5 Every robot movement requires a feedback

6 Robotic market sectors & requirements for feedback Industrial robots medium to high performance; proprietary solutions Collaborative robots safety functions, complex functions, compact Service robots (home assistance) low performance, low price Mobile robots and Agriculture autonomous vehicles robust, waterproof Medical / surgical robots small, lightweight, reliable Student learning & research projects new technologies Market status Mature Big growth Slowly rising Rising Rising Rising Direct drive motors for automatization universal, high performance Slowly rising

7 Robotic system design

8 Robotic arm system development Robot (motors & feedback) Integrated robot (integrated drives) Smart Robot (integrated drives & logic) Bulky cable Small cable Power cable / batteries (multi-conductor) (power & bus) Control cabinet Control cabinet (without cabinet) (logic, power, drives) (logic, control panel) Production supervision (computer) Mesh network Wireless network / fibre optic

9 Typical robotic joint

10 Closed loop drive systems 1 Current / commutation loop 3xHALL Velocity loop INC Position loop INC ABS

11 Closed loop drive systems 2 Current / commutation loop + Velocity loop + Position loop Running from a single encoder ABS + multiturn OR ABS (high res)

12 Smooth movement & encoder error Encoder error types Source: Poor installation (eccentric mounting of rotor injects 1st order error) Effect: Low frequency error Result: Vibration, incorrect positioning Source: Sub divisional error (low performance encoder); Noise (wrong installation - air gap) Effect: High frequency error Result: Noise in system, energy loss

13 Forgotten technical detail LATENCY Total system accuracy = Mechanical accuracy (eccentricity) + Encoder target (scale) accuracy + Electrical accuracy (SDE, noise) + Processing delay (latency)

14 Design considerations (requirements for the encoder) Mounting must be intuitive (reduce design time, short time to market) Wide installation tolerances (cheaper manufacturing, reduce assembly time) Plug n play Monitoring of parameters (runtime diagnostics) Data logging in production line allows full traceability

15 Safety and reliability Two encoders per axis (fully redundant) no need for safety One encoder per axis redundancy via sensorless motor commutation feedback Lots of safety features and safety checkpoints is recommended and welcome Good result of safety assessment SIL (Safety Integrity Level) standards are not required (yet); done on system level

16 Industrial robots vs. Collaborative robots

17 Classic robotic arms Industrial robots (classic) Motors on the outside On-axis encoders on the motors Lightweigth & collaborative Smaller, cheaper Motors, encoders inline inside the joint Hollow shaft encoders

18 Drive train of a classic robotic arm Servo motor with encoder Gear box End point Industrial Collaborative DDR motor Incremental encoder Gear box Absolute encoder End point

19 Requirements for a feedback system for a collaborative robot Typical configuration: Incremental encoder on a motor shaft (velocity feedback) Absolute encoder at the output shaft (position feedback) No influence by gearbox error, precise control Redundant feedback due to 2 encoders True absolute knows the position after power-up Through hole, no slip rings for cables Compact size, easy integration A lot of safety features Fast communication interface

20 Applications Case studies

21 Robotic market sectors & requirements for feedback COLLABORATIVE

22 Robotic market sectors & requirements for feedback GIMBALS Flying Handheld Underwater

23 Robotic market sectors & requirements for feedback OFF-ROAD VEHICLES Water transport, agriculture,... ON-ROAD VEHICLES Automotive standards, (ASIL)

24 Robotic market sectors & requirements for feedback. SURGERY, MEDICAL FDA approval on complete system, not encoders

25 Robotic market sectors & requirements for feedback RESEARCH & EDUCATION

26 Thank you. Contact:

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