Atalante X is intended to perform ambulatory functions and mobility exercises, hands-free, in rehabilitation institutions under the supervision of a trained operator for the following populations:

Individuals with hemiplegia due to cerebrovascular accident (CVA).
Individuals with spinal cord injuries at levels T5 to L5 (SCI).

The operator must complete a training program prior to use of the device.

Atalante X is intended to be used on adolescents of 18 years and older, and adults able to tolerate a stand-up position. The device is not intended for sports or stair climbing.

Device Description

Atalante X is a completely self-balancing walking system for people with mobility disabilities. It is a fully powered hip-knee-ankle lower body exoskeleton with 12 actuated degrees of freedom. Atalante X is selfbalancing and includes dynamic-walking control. Dynamic-walking allows the Atalante X to consume significantly less power and have a more natural gait.

AI/ML Overview

The provided text describes the Wandercraft SAS Atalante X, a powered lower extremity exoskeleton. The document is an FDA 510(k) premarket notification. It does not contain information about the acceptance criteria or a specific study proving the device meets those criteria, as typically found in a clinical study report. Instead, it focuses on demonstrating substantial equivalence to predicate devices through a comparison of characteristics and non-clinical/clinical performance data.

Therefore, many of the requested details about acceptance criteria, specific study design for ground truth, sample sizes for test/training sets, adjudication methods, and MRMC studies are not available in the provided document.

However, based on the information available, a summary of the performance demonstration is provided below, focusing on what can be extracted.

Table of Acceptance Criteria (Inferred from Performance Data) and Reported Device Performance

Since explicit acceptance criteria are not stated, the "acceptance criteria" are inferred from the safety and effectiveness claims made and the reported outcomes.

Acceptance Criteria (Inferred)	Reported Device Performance (Atalante X)
Safe operation (general)	Passed all non-clinical safety tests (Cytotoxicity, Irritation, Sensitization, Electrical safety, EMC, Software V&V, System V&V, Electronics V&V, Mechanics V&V, Cycling, Thermal, Useful Life, Transportation).
Effective in enabling ambulatory functions and mobility exercises for SCI patients at levels T5-L5.	The device could ensure ambulatory functions with comparable speed to that of the predicates while leaving upper limbs free for additional tasks.
Acceptable adverse event rate	24 adverse events in two clinical studies (majority minor skin lesions, one nausea, one incontinence). None serious.

Study Details

Detailed aspects of the clinical studies are limited in this summary.

Sample size used for the test set and data provenance:
- Test Set (Clinical Studies): 21 patients with spinal cord injury (SCI) across two clinical studies.
- Data Provenance: Not specified (e.g., country of origin). The document mentions "real world evidence of use." It is implied to be prospective for the two clinical studies.
- Real-world evidence: Over 481 patients, including 40 SCI patients at levels C3-L3, who performed 3 or more sessions. This broader "real-world" data is mentioned to support findings, not as a primary "test set" with a pre-defined ground truth assessment for evaluation.
Number of experts used to establish the ground truth for the test set and qualifications of those experts:
- Not specified. The clinical studies would likely have involved trained clinical staff to assess patient performance and adverse events, but the number and qualifications are not detailed. The device is intended to be used under the supervision of a "trained operator."
Adjudication method for the test set:
- Not specified.
If a multi-reader multi-case (MRMC) comparative effectiveness study was done, if so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- Not applicable. This device is an exoskeleton, not an imaging AI diagnostic tool. Therefore, MRMC studies involving human readers and AI assistance are not relevant.
If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- N/A (not directly applicable in the same sense as an AI diagnostic tool). The device itself is the "algorithm only" in terms of its automated function (dynamic-walking control). The performance claims relate to the device operating in its intended environment with human supervision. The "comparable speed to that of the predicates" is a standalone performance metric for the exoskeleton's function.
The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- For the clinical studies, the "ground truth" would be related to clinical measures of ambulatory function (e.g., ability to perform tasks, speed, mobility exercises) and safety events (e.g., skin lesions, other adverse events). These are clinical observations and patient outcomes, likely assessed by clinicians or trained operators.
The sample size for the training set:
- Not specified. The document mentions "Wandercraft Customer Care" visits and a "training program" for operators, but this "training set" refers to personnel training, not machine learning model training data. The device's control algorithms (dynamic-walking control) are developed through engineering and likely extensive non-clinical testing and internal validation, but a "training set" in the machine learning sense is not explicitly discussed as part of this submission summary.
How the ground truth for the training set was established:
- Not specified. As above, a traditional "training set" with ground truth in the context of machine learning is not detailed. The device's functionality is based on its mechanical and software design, which would be validated against engineering specifications and performance targets rather than a specific ground truth dataset for training a learning algorithm described in this document.

Summary

{0}------------------------------------------------

Image /page/0/Picture/0 description: The image shows the logo for the U.S. Food & Drug Administration (FDA). The logo consists of two parts: a symbol on the left and the text on the right. The symbol is a stylized representation of a caduceus, a traditional symbol of medicine, with intertwined snakes and wings. To the right of the symbol is the text "FDA U.S. FOOD & DRUG ADMINISTRATION" in blue, with "FDA" in a larger font size than the rest of the text.

December 13, 2023

Wandercraft SAS Maria Iacono, PhD Director of Regulatory and Quality Affairs 88 rue de Rivoli Paris, Ile-de-France 75004 France

Re: K232077

Trade/Device Name: Atalante X Regulation Number: 21 CFR 890.3480 Regulation Name: Powered Lower Extremity Exoskeleton Regulatory Class: Class II Product Code: PHL Dated: November 24, 2023 Received: November 24, 2023

Dear Dr. Iacono:

We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device"

{1}------------------------------------------------

(https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90. Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review. the OS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely.

Heather L. Dean -S

Heather Dean, PhD Assistant Director, Acute Injury Devices Team DHT5B: Division of Neuromodulation and Rehabilitation Devices OHT5: Office of Neurological

{2}------------------------------------------------

and Physical Medicine Devices Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

{3}------------------------------------------------

Indications for Use

510(k) Number (if known) K232077

Device Name Atalante X

Indications for Use (Describe)

Atalante X is intended to perform ambulatory functions and mobility exercises, hands-free, in rehabilitations under the supervision of a trained operator for the following populations:

Individuals with hemiplegia due to cerebrovascular accident (CVA).
Individuals with spinal cord injuries at levels T5 to L5 (SCI).

The operator must complete a training program prior to use of the device.

Atalante X is intended to be used on adolescents of 18 years and older, and adults able to tolerate a stand-up position. The device is not intended for sports or stair climbing.

Type of Use (Select one or both, as applicable)

X Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

CONTINUE ON A SEPARATE PAGE IF NEEDED.

This section applies only to requirements of the Paperwork Reduction Act of 1995.

DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.

The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to:

Department of Health and Human Services Food and Drug Administration Office of Chief Information Officer Paperwork Reduction Act (PRA) Staff PRAStaff(@fda.hhs.gov

"An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number."

{4}------------------------------------------------

510(k) Summary Atalante X

1. Submission Sponsor

Wandercraft SAS 88 rue de Rivoli 75004 Paris, France

Contact: Matthieu Masselin Title: Chief Executive Officer

2. Submission Correspondent

Wandercraft SAS 88 rue de Rivoli 75004 Paris, France Email: reglementaire@wandercraft.eu

Contact: Maria Ida Iacono, PhD Title: Chief of Regulatory, Quality, and Clinical Affairs – Global

3. Date Prepared

July 13th, 2023

4. Device Identification

Trade/Proprietary Name:	Atalante X
Common/Usual Name:	Powered Exoskeleton
Classification Name:	Powered lower extremity exoskeleton
Regulation Number:	890.3480
Product Code:	PHL
Class:	II
Classification Panel:	Neurological and Physical Medicine Devices (OHT5)

{5}------------------------------------------------

5. Legally Marketed Predicate Devices

	Primary Predicate	Secondary Predicate
Device name	Atalante	Indego®
510(K) number	K221859	K173530
Regulation Number	21 CFR 890.3480	21 CFR 890.3480
Regulation Name	Powered Exoskeleton	Powered Exoskeleton
Product code	PHL	PHL
Review Panel	Neurology	Neurology
Manufacturer	Wandercraft SAS	Parker Hannifin Corp.
FEATURE	Subject DeviceAtalante X	Primary PredicateAtalante	Secondary PredicateIndego®
510(k) Number	TBD	K221859	K173530
Manufacturer	Wandercraft SAS	Wandercraft SAS	Parker Hannifin Corp.
Product Code	PHL	PHL	PHL
Regulation	890.3480	890.3480	890.3480
RegulationName	Powered Exoskeleton	Powered Exoskeleton	Powered Exoskeleton
Indications forUse	Atalante X is intended to performambulatory functions andmobility exercises, hands-free, inrehabilitation institutions underthe supervision of a trainedoperator for the followingpopulations:- Individuals with hemiplegia dueto cerebrovascular accident(CVA)- Individuals with spinal cordinjuries at levels T5 to L5 (SCI)The operator must complete atraining program prior to use ofthe device.Atalante X is intended to be usedon adolescents of 18 years andolder, and adults able to toleratea stand-up position.The device is not intended forsports or stair climbing.	The Atalante exoskeleton isintended to enable individualswith hemiplegia due tocerebrovascular accident (CVA)to perform ambulatory functionsand mobility exercises, hands-free, in rehabilitation institutionsunder the supervision of a trainedoperator.The operator must complete atraining program prior to use ofthe device.The Atalante system is intendedto be used on adolescents of 18years and older and adults, ableto tolerate a stand-up position.The device is not intended forsports or stair climbing.	The Indego® orthotically fits tothe lower limbs and the trunk; thedevice is intended to enableindividuals with spinal cord injuryat levels T3 to L5 to performambulatory functions withsupervision of a specially trainedcompanion in accordance withthe user assessment and trainingcertification program. The deviceis also intended to enableindividuals with SCI at levels C7 toL5 to perform ambulatoryfunctions in rehabilitationinstitutions in accordance withthe user assessment and trainingcertification program. Finally, theIndego® is also intended toenable individuals withhemiplegia (with motor functionof 4/5 in least one upperextremity) due tocerebrovascular accident (CVA)to perform ambulatory functionsin rehabilitation institutions inaccordance with the userassessment and trainingcertification program.The Indego is not intended forsports or stair climbing.
Population	Adolescents of 18 years andolder, and adults	Adolescents of 18 years andolder, and adults	Adults over age of 18
Environment	Rehabilitation institutions	Rehabilitation Institutions	Rehabilitation Institutions
Body Coverage	Worn over legs and upper bodywith rigid torso	Worn over legs and upper bodywith rigid torso	Worn over legs and around hipswith lower torso
Size ofComponents	Adjustable upper leg, lower leg.Non-adjustable hip width;	Adjustable upper leg, lower leg.Non-adjustable hip width;	Modular Small, Medium andLarge upper leg, lower leg and hipcomponents;
Mobility Aid	None	None	Walker, Crutches, Cane
FEATURE	Subject DeviceAtalante X	Primary PredicateAtalante	Secondary PredicateIndego®
User Mobility	Sit, stand, walk, turn, exercise(weight shift, squat),repositioning	Sit, stand, walk, turn, exercise(weight shift, squat),repositioning	Sit, stand, walk, and turn
Walking Speed	~2km/hr	~2km/hr	~2 km/hr
Type ofSurface	Smooth	Smooth	Smooth, cement, carpet
Range ofMotion	Hip: 90° flexion,5° extension;17° abduction,10° adduction;10° medial rotation,20° lateral rotationKnees: 110° Flexion;-5°Extension:Ankle: 0 dorsiflexion,9° plantar flexion,18° pronation and supination	Hip: 90° flexion,5° extension;17° abduction,10° adduction;10° medial rotation,20° lateral rotationKnees: 110° Flexion;-5°Extension:Ankle: 0 dorsiflexion,9° plantar flexion,18° pronation and supination	Hips: 110° flexion to 30° extensionKnees: 110° flexion to 10°extension
RechargeableBattery	Rechargeable Lithium-ion battery46.8 V, 6,4AhUsage duration: 2h of continuoususage per charge	Rechargeable Lithium-ion battery46.8 V, 9 AhUsage duration: 2h of continuoususage per charge	Rechargeable lithium ion.33.3 V, 36A peak current, 12Acontinuous current. 159Wh fullycharged;Usage duration: 1.5h ofcontinuous usage per charge
Battery ChargeTime	2h 30min	4h	4h
TrainingProgram	Yes	Yes	Yes
CertificationProgram	Yes	Yes	Yes
User Feedback	Provides visual feedback on thehandheld controller and physiointerface, and auditory feedback	Provides visual feedback on thehandheld controller and operatorinterface, and auditory feedback	Provides vibratory feedback andLED indicators on top of hip unit,visible to wearer
Fall Detectionand Mitigation	Must be used in combination withsafety rail	Must be used in combination withsafety rail	Detects forward, backward andsideways falling as it is happening;the device makes adjustmentsduring the course of the fall toposition the user for minimal riskof injury or allow the user toattempt to recover unassisted
FailsafeFeature	(use of safety rail)	(use of safety rail)	In the event of power failureknees become locked and hipsfree (similar to typical passive legbraces)
ElectricalTesting	ANSI AAMI ES60601-1:2005/(R)2012 AndA1:2012.	ANSI AAMI ES60601-1:2005/(R)2012 And A1:2012	ANSI/AAMI ES60601-1:2005/(R)2012
EMC Testing	IEC 60601-1-2 2020AIM 7351731:2021	IEC 60601- 1-2:2014AIM 7351731:2021	IEC 60601-1-2: 2014

6. Indication for Use Statement

Atalante X is intended to perform ambulatory functions and mobility exercises, hands-free, in rehabilitation institutions under the supervision of a trained operator for the following populations:

Individuals with hemiplegia due to cerebrovascular accident (CVA)
. Individuals with spinal cord injuries at levels T5 to L5 (SCI)

The operator must complete a training program prior to use of the device.

Atalante X is intended to be used on adolescents of 18 years and older and adults, able to tolerate a standup position.

The device is not intended for sports or stair climbing.

7. Device Description

8. Substantial Equivalence Discussion

The following table compares Atalante X to the predicate devices with respect to indications for use, principles of operation, technological characteristics, materials, and performance, and forms the basis for the determination of substantial equivalence. The subject device does not raise any new questions of safety or effectiveness as compared to the predicate devices.

{6}------------------------------------------------

Table 5A – Comparison of Characteristics

{7}------------------------------------------------

{8}------------------------------------------------

9. Non-Clinical Performance Data

To demonstrate safety and effectiveness of Atalante X and to show substantial equivalence to the predicate devices, Wandercraft SAS completed the following non-clinical tests. Results confirm that the design inputs and performance specifications for the device are met. Atalante X passed the testing in accordance with internal requirements, national standards, and international standards shown below, supporting its safety and effectiveness, and its substantial equivalence to the predicate devices:

Cytotoxicity testing per ISO 10993-5: Passed
. Irritation and Sensitization testing per ISO 10993-10: Passed
Electrical safety testing per ANSI/AAMI 60601-1: Passed
Electromagnetic Interreference (EMI) testing per IEC 60601-1-2: Passed
Software verification and validation per IEC 62304 and FDA Guidance – the current version has been fully validated
System (Device) Verification and Validation: Passed
Electronics Sub-system Verification: Passed
. Mechanics Sub-system Verification: Passed
Cycling Testing: Passed
Thermal Testing: Passed
Useful Life Testing supports 5 years ●
Transportation Testing per ASTM D4169 demonstrates package integrity is maintained: Passed ●

10. Clinical Performance Data

Two clinical studies with a total of 21 patients with spinal cord injury (SCI) were undertaken. The device could ensure ambulatory functions with comparable speed to that of the predicates while leaving upper limbs free potentially for additional tasks. The findings are supported by real world evidence of use by over 481 patients which performed 3 sessions or more, including 40 SCI patients at levels C3-L3 who performed a total of 560 sessions.

There were altogether 24 adverse events in both clinical studies, majority of which were minor skin lesions, one occurrence of nausea and one of incontinence. None of them was serious.

Clinical data demonstrate that patients with SCI at levels T5-L5 can use Atalante X safely and effectively.

11. Training

Prior to the first use of Atalante X, to ensure safe and effective operation of the device, the operator must complete a certification training. To optimize the integration of the clinical setting, such training is then followed by frequent visits by Wandercraft Customer Care to further support the operator with the exoskeleton. The training program is offered for as many operators as agreed in the contract signed with the customer.

Training is composed by a theoretical part including presentation and description of the whole system and its mode of operations and a hands-on practice. This latter will be performed both in pairs – with an operator in the role of "operator" and another operator in the role of a "patient" – and in individual

{9}------------------------------------------------

sessions. The double role allows the operators to understand the device from both the operator's and patient's perspectives.

An operator is considered certified, i.e., with proven competence to safely operate Atalante X alone with the patient, only after fulfilling all eligibility requirements and pass the certification evaluation.

12. Statement of Substantial Equivalence

Atalante X has the same intended use as the Atalante and Indego® predicate devices, and the same or similar technological characteristics. The differences in technological characteristics do not raise new or different questions of safety and effectiveness. Performance testing has demonstrated that Atalante X is as safe and effective as the predicate devices. Therefore, Atalante X is substantially equivalent to the predicate devices.

Regulation Number and Section

§ 890.3480 Powered lower extremity exoskeleton.

(a)
Identification. A powered lower extremity exoskeleton is a prescription device that is composed of an external, powered, motorized orthosis that is placed over a person's paralyzed or weakened limbs for medical purposes.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Elements of the device materials that may contact the patient must be demonstrated to be biocompatible.
(2) Appropriate analysis/testing must validate electromagnetic compatibility/interference (EMC/EMI), electrical safety, thermal safety, mechanical safety, battery performance and safety, and wireless performance, if applicable.
(3) Appropriate software verification, validation, and hazard analysis must be performed.
(4) Design characteristics must ensure geometry and materials composition are consistent with intended use.
(5) Non-clinical performance testing must demonstrate that the device performs as intended under anticipated conditions of use. Performance testing must include:
(i) Mechanical bench testing (including durability testing) to demonstrate that the device will withstand forces, conditions, and environments encountered during use;
(ii) Simulated use testing (
i.e., cyclic loading testing) to demonstrate performance of device commands and safeguard under worst case conditions and after durability testing;(iii) Verification and validation of manual override controls are necessary, if present;
(iv) The accuracy of device features and safeguards; and
(v) Device functionality in terms of flame retardant materials, liquid/particle ingress prevention, sensor and actuator performance, and motor performance.
(6) Clinical testing must demonstrate a reasonable assurance of safe and effective use and capture any adverse events observed during clinical use when used under the proposed conditions of use, which must include considerations for:
(i) Level of supervision necessary, and
(ii) Environment of use (
e.g., indoors and/or outdoors) including obstacles and terrain representative of the intended use environment.(7) A training program must be included with sufficient educational elements so that upon completion of training program, the clinician, user, and companion can:
(i) Identify the safe environments for device use,
(ii) Use all safety features of device, and
(iii) Operate the device in simulated or actual use environments representative of indicated environments and use.
(8) Labeling for the Physician and User must include the following:
(i) Appropriate instructions, warning, cautions, limitations, and information related to the necessary safeguards of the device, including warning against activities and environments that may put the user at greater risk.
(ii) Specific instructions and the clinical training needed for the safe use of the device, which includes:
(A) Instructions on assembling the device in all available configurations;
(B) Instructions on fitting the patient;
(C) Instructions and explanations of all available programs and how to program the device;
(D) Instructions and explanation of all controls, input, and outputs;
(E) Instructions on all available modes or states of the device;
(F) Instructions on all safety features of the device; and
(G) Instructions for properly maintaining the device.
(iii) Information on the patient population for which the device has been demonstrated to have a reasonable assurance of safety and effectiveness.
(iv) Pertinent non-clinical testing information (
e.g., EMC, battery longevity).(v) A detailed summary of the clinical testing including:
(A) Adverse events encountered under use conditions,
(B) Summary of study outcomes and endpoints, and
(C) Information pertinent to use of the device including the conditions under which the device was studied (
e.g., level of supervision or assistance, and environment of use (e.g., indoors and/or outdoors) including obstacles and terrain).